What are steel and cast iron

Impact strength of steel - what is it, testing of metals, designation, for what purpose is it determined, diagram

15Nov

articles

Sometimes the strongest material, for example, cast iron, becomes brittle when exposed to certain mechanical external loads, while soft aluminum (we all bent aluminum spoons in kindergarten) in some cases turns out to be more adaptable and does not crumble or break. In the article we will tell you why this happens, and also talk about testing metals for impact strength - what this characteristic is for steel, in what units it is measured.

What is impact resistance and how is it measured?

Let's imagine the situation. A car is driving along the road at fast speed. Throughout its journey, it constantly experiences vibrations and axial loads on a number of parts and the suspension. However, everything is fine, all nodes are working correctly. Then the driver loses control and falls into a hole. Spare parts fail because internal stresses and forces, firstly, increase, and secondly, they become multidirectional.

The strength in this situation turned out to be low, since it was deformed and failed. Since different alloys tolerate mechanical and chemical influences differently, it is necessary to use different metals for different purposes (automotive industry, machine tool industry, ordinary stamping parts, nails, etc.).

Designation of impact strength - what ability of the material characterizes: what is it called

Let's define the terminology. it is the ability to perceive and absorb kinetic energy. Often such an applied force leads to destruction, but in relation to this substance - only to plastic or non-plastic deformations.

Tests are usually carried out experimentally in a laboratory. Workpieces of the same size under neutral conditions (so that there is no longer any temperature or other influence) are subjected to loads, increasing them. Then the behavior of the metal is observed. They check the susceptibility to counteraction, so the last check is the one from which cracks appeared on the prototype, a part broke off.

The second option is mathematical calculations. This is a more accurate process, but it is necessary to be guided by numerous nuances - from size, angle of application of force, to external influences.

What is it measured in and how is it designated?

Physical designation KS. These letters are used to sign the parameter on diagrams and drawings, and also substitute it in formulas. The unit of measurement in the system of international units is kJ/m2, but the value expressed in J/cm2 is more often used.

Now it would be appropriate to give the formula by which the mathematical calculation is made.

KS = A / F, where:

• A is force, the work applied to the impact is measured in joules.
• F is the cross-sectional area of ​​the sample, in square meters.

This is a simplified calculation algorithm, while in laboratory conditions thickness and mass, the degree of heat treatment are taken into account, and they also experiment with other indicators.

What does impact strength and specific value testing of materials depend on?

The first parameter that greatly changes the research results is temperature. It was known even earlier that when heated, alloys become softer and more susceptible to deformation; it is for this reason that heat treatment is used in forging. But at very low temperatures or with large differences, fragility increases.

In this regard, the optimal temperature regime is usually determined - those maximum and minimum operating values ​​during which the best performance can be achieved. Then the researchers gradually reduce the degrees down to minus 80 or 100. At each cooling stage, the workpieces are checked.

A diagram is obtained according to which cold brittleness, brittleness, strength, and temperature of plastic deformation can be determined. The second value is the chemical composition of the components - the presence of alloying substances and the amount of carbon. According to this, all steel is divided into grades.

If the part has been welded, there is a high probability of martensite formation. This needle-type metal microstructure can lead to reduced strength. And the last indicator that researchers change is the rate of deformation. The result also depends on the speed of stress and their sequence.

Samples for testing materials for impact strength

Not all items can be tested. Since there is a kilogram standard that is ideally verified to the thousandth, only identical experimental specimens created in accordance with GOST are supplied to the laboratory. They can be of three types:

• Sharpie bars. This is rolled metal with a square cross-section with a side of 10 mm. It should be exactly 55 mm in length. There is no hollow hole inside, but there is a cut in the shape of the letter U. It is shown in the drawing below:
• Bar Menage. The previous parameters are the same, only the cut is different, which is made in the shape of the letter V. Such a sharp end of the cut leads to the fact that deformations or destruction will appear sooner than the previous one. Therefore, tests are necessary to determine the performance characteristics of systems subject to constant high loads, such as machine or vehicle components.
• The T-shaped cut is used in cases where even greater complexity and accuracy are needed, so the cut is made in the shape of the letter T.

There are several types of procedures. Its choice depends on the purpose for which the impact strength of the material is determined. From this the testing will be selected:

• method of fastening on the stand;
• using a weight or hammer as a tool;
• type of cut.

Pendulum pile driver

This is one of the most regular experiments, so we will describe it from the preparatory stage to the evaluation. The first and important rule is that all experimental bars must be completely identical in size, and they should also be manufactured simultaneously, under the same conditions - both from the point of view of the chemical composition of the alloy and from the metalworking side. Performance can be assessed by one of the following characteristics:

• fracture, cracks - this reaction is characteristic of either brittle steels, for example, cast iron (it is very strong, but has internal stresses);
• dents, scratches - they can be seen on a plastic material that is easily subject to deformation during dynamic or static influences.

Sampling

The entire technology for manufacturing blanks for experiments is prescribed in the corresponding regulatory document - GOST 7565. You should fully follow the standards therein, but sometimes a special technical order is received, for example, when special operating conditions for the part are predetermined. Then you can carry out the procedure according to the requirements, however, it is important that the temperature regime remains within the limits of the invariability of the crystal lattice.

Definition: How is impact strength measured?

The first tests with a pendulum were proposed by Georges Charpy, it is for this reason that his method is still used today and is named after him. His idea was this: the incision increases sensitivity. The test is accompanied by a cooling of the surrounding conditions, and at the same time a transition of the metal from a ductile to a brittle state.

Charpy method

It consists of two sequential actions:

• bar cut;
• influence with different speed and mass.

Accordingly, we present the Charpy formula KS = K / F, where:

• K is work, that is, force, which usually consists of the weight of the weight and the speed of its movement.
• F is the area of ​​influence.

Algorithm (scheme) for impact strength testing

• The workpiece is attached at two ends to two pile drivers so that the cut is opposite the place where the force will be directed.
• The pendulum rises to the top - maximum swing.
• When falling from this height, the sample is destroyed and subsequently raised to a shorter distance.

Methodology

The following nuances are important:

• accuracy of bar installation with an error of no more than 0.5 mm;
• it is necessary to equip the experiment site with equipment for determining force;
• Heating or cooling must be done gradually.

Determination of impact strength and dimension at low temperatures

We have already explained that after a series of tests, a certain diagram is formed. The curve has two thresholds - a minimum, brittleness, which occurs due to overcooling, and a maximum, when heating changes the crystal lattice of the alloy.

Other tests

A hammer can be used instead of a pendulum. In addition to the impact resistance of metal workpieces, it is necessary to check for stretching and torsion, and for fracture. All this gives a complete comprehensive picture of a particular material for construction.

Table with indicators

There is no need to carry out experiments every time, since most of them have already been done. It is enough just to use the proposed GOSTs. Here are the figures for the various most common steel grades:

Steel gradeRolled product thicknessImpact strength, J/cm2, not less

KCU	KCV
St3ps	3,0 — 5,0	—	49	—	9,8
St3sp	5,1 — 10,0	108	34	—
St3Gps	10,1 — 26,0	98	29	—
St3Gsp	26,1 — 40,0	88	—	—
For St3ks - not standardized

Determination of the cold brittleness threshold

To do this, it is necessary to continue testing using the Charpy method and record the negative temperature at which fragility increases. The threshold is not instantaneous; it usually consists of two temperature points - maximum and minimum.

Processing the results obtained

After testing, either failure or deformation will be obtained. In the first case, you need to record this and then continue testing, but using little effort. And in the second, the results should be subjected to mathematical calculations using the above formula.

In the article we explained how impact strength is designated and how to find it out. To complete the topic, watch the video:

On the Rokta website you can learn about other properties of metals, as well as find a wide range of equipment for band sawing. Go to our catalog to find out more.

To clarify the information you are interested in, contact our managers by phone 8 (908) 135-59-82; (473) 239-65-79; 8 (800) 707-53-38. They will answer all your questions.

Source: http://rocta.ru/info/udarnaya-vyazkost-stali-i-metallov-chto-ehto-takoe-ispytanie-s-kakoj-celyu-opredelyayut-udelnoe-oboznachenie/

Properties of cast iron

Cast iron is an alloy of iron with carbon, as well as other elements.

Characteristics of cast iron

An important factor in the production of cast iron is that the minimum amount of carbon in the alloy is 2.14% or more. If the carbon content in the alloy is below the specified amount, then this alloy is not cast iron, but is called steel. The production process for steel and cast iron is approximately the same. The main difference between these two alloys is the quantitative carbon content in their composition.

Since cast iron contains more carbon than steel, cast iron is a very strong but brittle material. While steel is very flexible. It is the high carbon content in cast iron that gives this material its exceptional hardness, which is as much as 7.5 on the Mohs scale.

This indicator is significantly higher than that of quartz, however, less than that of diamond, but only by 2.5 points.

The carbon in cast iron can be cementite and graphite. It is the shape of graphite and the quantitative content of cementite in the alloy that determines the type of cast iron. Thus, cast iron is divided into white, gray, malleable and high-strength. The chemical composition of cast iron, which contains impurities such as silicon, manganese, sulfur and phosphorus, is almost always constant.

However, in some cases, cast iron may also contain the following alloying elements: chromium, nickel, aluminum, vanadium and others. These components are introduced into the alloy in order to give it greater strength, wear resistance, heat resistance, corrosion resistance, and non-magneticity. Cast iron containing these impurities is called alloy cast iron.

The quantitative content of these impurities in the alloy determines the degree of alloying. Depending on this, there are:

• low alloy cast iron. It contains less than 2.5% of all alloying impurities;
• medium alloy cast iron. Here the impurities are about 2.5 - 10%;
• highly alloyed, containing more than 10% alloying elements.

The chemical characteristics of alloy cast irons are the main factor for their classification. Thus, among alloyed cast irons there are:

• aluminum cast iron. It contains aluminum in amounts from 0.6 to 31%. This cast iron is stronger, more heat-resistant, corrosion-resistant, and also has high wear resistance. The use of this alloy is appropriate where work is carried out in an aggressive environment and at high temperatures - thermal furnaces, chemical equipment, gas engines.
• nickel cast iron. It contains nickel in amounts ranging from 0.3-0.7% to 19-21%. nickel directly affects the shape of graphite precipitates in the structure of nickel cast iron. This alloy has such properties as high resistance to corrosion, high resistance to the effects of both high and fairly low temperatures on the material (heat resistance and cold resistance), and is also able to withstand exposure to such an aggressive environment as sea water. The latter property of nickel cast iron determines the high demand for this material in shipbuilding, as it is used for the manufacture of parts operating in sea water.
• chromium cast iron. This alloy contains about 32% chromium. This type of alloy cast iron has the following properties: heat resistance, corrosion resistance, wear resistance.

It is worth noting that in general the cost of alloy cast iron is significantly lower than the cost of stainless steel. In addition, they have good casting properties. In this regard, products made from this alloy are very durable, high quality, and at the same time economical.

Pig iron is extracted through the process of smelting iron ore in blast furnaces at temperatures ranging from 1150 to 12000C.

History of cast iron

Cast iron has been known to mankind since ancient times, which go back to the era BC. This is evidenced by numerous archaeological finds, among which there are both cast iron objects and the cheese furnaces themselves, in which, in fact, people received this material.

However, iron is far from the first historical metal with which humanity became acquainted. Initially, people used native copper, which was mined in shallow mines. However, despite the appearance of metal in people's lives, stone remained very popular for quite a long time.

Later, people learned to make bronze, and only in VI-V BC iron appeared in people's lives, and with it steel and cast iron.

The birthplace of cast iron products is China. It was there that the technology of cast iron was first mastered and this term was born, which later came to Russia through Tatar-Mongol mediation. Thus, the first cast iron products also appeared in China. It was a wide variety of everyday items, kitchen utensils, as well as coins.

The wok frying pan, quite popular today, was one of the first to be made in China from cast iron. In those distant times, it was a vessel whose diameter reached one meter. This frying pan also had very thin walls.

Its cost was quite high, however, despite this, this kitchen equipment was extremely popular and in demand in large Chinese families.

In addition, archaeologists find unique things cast from cast iron, among which we should note a cast iron lion, which is 6 meters high and 5 meters long. According to scientists, this statue was cast in one go. This indicates that in those distant prehistoric times, in the absence of modern high-quality technologies, Chinese metallurgists achieved enormous skill in working with metals, in particular with cast iron.

A rather interesting and somewhat unusual fact is that it is believed that malleable cast iron began to be produced only in the 19th century AD, despite the fact that archaeologists have found cast iron swords made in the pre-Christian era.

Russia and Europe became acquainted with cast iron more than a century later, namely only in the 14th – 16th centuries. At this time, cast iron was the main material for the production of artillery shells and weapons. And only in the 17th century the use of cast iron expanded significantly. This was facilitated by the development of the metallurgical industry.

Gradually, the era of artillery use of cast iron ended and the era of artistic casting began - the new capital of the Russian Empire was decorated everywhere with cast fences, benches, and other elements of fine cast iron.

Cast iron also caused changes in the stove business, as cast iron valves and stove doors were replaced, which had the significant advantage of resistance to high temperatures, as well as tightness, which did not allow stove smoke to escape from the stove and fill the room with smoke.

Russian metallurgists were considered the best in those days. They mastered many cast iron processing technologies, which were constantly adopted by English, French and German craftsmen.

Today, in the era of nanotechnology and technological progress, when new materials appear every year, the development of metallurgy does not stop and continues to move forward. And after more than two thousand years, humanity has not been able to find a material that could replace cast iron. It continues to be used to make various objects that surround people.

Use of cast iron

The properties of cast iron are so unique that to date no more suitable material has been found that could replace this alloy. In addition, cast iron is a fairly cheap material.

In this regard, the use of cast iron remains wide and varied. The use of cast iron is especially appropriate where parts with complex shapes and high strength must be manufactured.

In this regard, cast iron has found its wide application in the following areas of human activity:

• Automotive industry. In this case, cast iron with vermicular graphite is used. It is the main material for the manufacture of crankshafts of diesel engines, as well as cylinder blocks of internal combustion engines. Due to the graphite content, the strength of the alloy increases significantly, which is the main reason for the popularity of cast iron in this industry.
• plumbing equipment. As with the automotive industry, graphite cast iron is also used. This material is perfect for the production of pipes used for both drainage and water supply. It is also actively used in the production of bathtubs, sinks, washstands, fittings and much more. In this case, the products are highly reliable, do not require any specific care, and retain their original appearance for a long period.
• Oil and gas industry. Not only water pipes are made from cast iron, but also pipes for transporting, injecting and pumping out oil and gas. The main reason for using cast iron in this industry is that cast iron products have fairly high performance qualities.
• heating. Pipes and heating radiators are made from cast iron. The use of the material in this case is due to its high heat transfer, as well as good heat-storing properties, which is very important and beneficial. After turning off the heating, after an hour, cast iron pipes are able to continue to radiate heat at a third of their original power. And here cast iron completely prevails over steel, which cannot boast of such qualities, because steel pipes cool twice as fast.
• kitchen tools. The material has large pores, due to which it has the ability to absorb fat during cooking. In this regard, pots, cauldrons and frying pans are made from cast iron, the non-stick properties of which become better and better over the years. In addition, scientists have proven that when cooking in cast iron cookware, food is enriched with beneficial nutritional properties. In addition, cast iron cookware can prevent carcinogens during further storage of food.

Fences and gratings, spiral staircases, balconies, gazebos, fireplaces, lamps, pillars, lanterns, sculptures, etc. are made from cast iron.

How to identify cast iron

Knowing the material from which certain objects are made is very important. For example, it is necessary to carry out repair work on certain automotive components, individual parts or other items. This is due, first of all, to the fact that different materials lend themselves to different types and methods of processing (for example, welding, drilling, etc.).

So, cast iron can in some cases be determined visually. However, this method is suitable if there are any cracks, chips or tears in the material. If any such defects are present, it should be carefully inspected. A cast iron part that is broken or cracked will be painted dark gray and have a matte surface. While steel will have a light gray, closer to white, color and glossy shine.

If you look closely at the surface defects, cast iron will have characteristic hemispherical small grains. Unfortunately, this method is not an accurate determination of the material, since it is possible to determine “by eye” whether it is cast iron or not only if the alloy (in this case cast iron) was poured into the mold at a low temperature, was not further processed and was not coated no paints and varnishes.

It is the characteristic small hemispherical grains that indicate the pouring of the alloy at high temperatures.

The mechanical method can provide more information in determining cast iron. To do this, it is necessary to obtain alloy shavings. This can be done by drilling to a shallow depth in some area of ​​the non-working part. For high-strength cast iron, the shavings will be characteristic - they will crumble, grinding into dust in the hands and leaving a mark on the fingers, similar to the lead of a simple pencil. Cast iron shavings are not able to wrap themselves in a twisted rope. This is due to one of the properties of cast iron - fragility.

If you try to cut a cast iron product with a grinder, then short sparks will fly from it, having a reddish tint on the star at the end of the track.

All of these options are valid for determining cast iron at home. However, they cannot give a 100% determination. To more accurately determine the alloy, spectral analysis, microscopic analysis, as well as weighing and volume determination are used.

Cast iron

Source: http://mining-prom.ru/rud/zhelez/svoystva-chuguna/

Waste hazard class 5: is a license required for transportation, disposal and processing?

Waste resulting from industrial and consumer activities of people is divided into 5 hazard classes based on distinctive features.

The first is assigned to garbage that is extremely harmful to the environment and does not decompose on its own. With subsequent classes, the potential danger to nature decreases.

We have already talked about the procedure for licensing hazardous waste management activities, now let’s talk about whether a license is needed to work with hazard class 5 waste - conditionally safe waste.

What is non-hazardous waste?

The last 5th class includes garbage that practically does not harm the ecosystem and human health. It decomposes in up to 3 years. Such waste in most cases is the remains of daily human activities .

Among them:

• food - cleaning, leftover food, including from catering establishments, expired products;
• household - waste polyethylene, bags, ordinary electric lamps, garbage after cleaning any premises and streets;
• paper - newspapers, books, paper, corrugated cardboard, scraps, as well as wood chips, ash, sawdust;
• construction - crushed stone, cast iron, steel, gypsum, broken brick, hard cement, ceramics;
• packaging - large-sized wooden boxes, cardboard containers;
• technical - cable insulation, abrasive wheels.

The full list is presented in the FKKO, acting on the basis of the order of Rosprirodnadzor dated July 18, 2014 No. 445. According to this federal catalog, all types of waste are designated by separate eleven-digit codes . The first 8 characters indicate the type and composition of the garbage, the 9th and 10th - its form, physical state, the 11th - hazard class. The non-hazardous waste code has a 5 at the end.

FCKO is updated and supplemented annually. The list of waste of the last class is gradually being reduced. Certain species are transferred to low-hazard class 4, after which work with them becomes licensed.

Job requirements

The Law of June 24, 1998 N 89-FZ “On Production and Consumption Waste” states that a license is not required for activities with class 5 waste. But this does not mean that you can handle non-hazardous waste uncontrollably.

Source: https://rcycle.net/othody/litsenzii/nuzhna-li-na-5-klass-opasnosti

Cast iron

Cast iron began to be used many decades ago. This material has special performance characteristics that differ from those characteristic of steel. The production of cast iron, despite the emergence of a large number of different alloys, is established in many countries. In order to determine the properties of cast iron, one should consider the features of its chemical composition, on which certain physical qualities depend.

Cast iron

The chemical composition of cast iron is an important factor that largely determines the mechanical properties of the resulting castings. In addition, many properties are influenced by the mechanisms of primary and secondary crystallization.

carbon in cast iron can vary from 2.14 to 6.67 percent. Modern production technologies make it possible to control the concentration of all elements in the composition with high precision, thereby reducing the fragility index and increasing other performance characteristics.

Considering the chemical composition of cast iron, it should be noted that, in addition to iron and carbon, it necessarily includes the following elements:

1. Silicon (concentration no more than 4.3%). This element has a beneficial effect on cast iron, making it softer and improving its casting properties. However, too high a concentration may make the material more susceptible to plastic deformation.
2. Manganese (no more than 2%). By adding this element to the composition, the strength of the material increases significantly. However, too high a concentration can cause the structure to become brittle.
3. Sulfur is a harmful impurity that can significantly impair the performance of the material. As a rule, the concentration of sulfur in cast iron does not exceed 0.07%. Sulfur causes cracks to appear when the composition is heated.
4. Phosphorus is contained in the composition in a concentration of less than 1.2%. An increase in the concentration of phosphorus in the composition causes cracks to appear when the composition cools. In addition, this element causes deterioration of other mechanical properties.

As with many other compounds, the most important chemical element in cast iron is carbon. The type of material depends on its concentration and type. The structure of cast iron can vary significantly depending on the production technology used.

Physical properties

Cast iron has become widespread due to its attractive physical properties:

1. The cost of the material is significantly lower than the cost of other alloys. That is why it is used to create a wide variety of products.
2. Considering the density of cast iron, we note that this indicator is significantly lower than that of steel, due to which the material becomes much lighter.
3. The melting point of cast iron can vary slightly depending on its structure, but in most cases it is 1,200 degrees Celsius. Due to the inclusion of various additives in the composition, the melting point of cast iron can significantly increase or decrease.
4. When choosing a material, many pay attention to the fact that the color of cast iron may differ slightly depending on the structure and chemical composition.

The boiling point of cast iron also largely depends on the chemical composition. In order to consider the physical properties of a material, attention should be paid to each of its varieties. A different structure and chemical composition cause different physical and mechanical properties to be imparted.

Production technology

Cast iron has been smelted for several decades, which is due to its unique performance qualities. The large number of varieties of alloys determines the application of special marking rules. Marking of cast iron is carried out as follows:

1. Foundries are designated by the letter L.
2. Gray has become widespread; the combination of letters “SCH” is used to designate it.
3. Malleable is designated KCH.
4. Extreme or white is designated by the letter P.
5. Anti-friction or gray indicate ASF.
6. Alloy cast irons can have a wide variety of chemical compositions and are designated by the letter “C”.

The technology of cast iron production involves several stages that make it possible to obtain the required structure. Considering the process of producing cast iron, we note the following points:

1. Production is carried out in special blast furnaces.
2. Alloyed and heat-resistant cast iron can be obtained by using iron ore as a raw material.
3. The technology is presented in the reduction of iron oxides ore. As a result of the restructuring of the crystal lattice and changes in the structure, the output is a material called cast iron.
4. Considering production methods, we note that the features of the technology also lie in the materials used - cokes. Coke refers to natural gas or thermoanthracite, which acts as fuel.
5. The production of cast iron involves tempering iron in solid form using a special furnace. At this stage, liquid cast iron is obtained.

Equipment for the production of cast iron can vary significantly. In addition, the production technology used largely determines what kind of material will be obtained. An example is the production of ductile iron, which involves giving the structure an unusual shape.

There are quite a large number of varieties of the material in question. The classification of cast iron largely depends on the structure and chemical composition. The following types of cast iron are distinguished:

1. Grey. This type of material is characterized by low ductility and high viscosity, as well as good machinability. Carbon is contained in the form of graphite. Area of ​​application – mechanical engineering; production of wear parts. As practice shows, phosphorus concentration can vary over a fairly wide range: from 0.3 to 1.2%. Due to its special chemical composition, the material has high fluidity and is often used in artistic casting. Anti-friction cast iron is relatively inexpensive, which also determines its widespread use.
2. White. Due to the fact that in this composition carbon is presented as cementite, the structure is characterized by extreme fragility and increased hardness, as well as low casting properties and poor machinability. It is worth considering that white cast iron is used for conversion into steel or for the manufacture of malleable iron. Very often it is called the limit.
3. Half-type is characterized by increased wear resistance, which is associated with the distribution of carbon into a cementite and free base. Often this type of material is used in mechanical engineering and machine tool building.
4. Alloy. In order to give special properties to cast iron, alloying is also carried out. Alloy cast iron has increased wear resistance and corrosion resistance due to the inclusion of nickel and chromium, as well as copper. Such versions of cast iron get their name depending on how the alloying element was used in their manufacture.
5. Ductile iron is produced by introducing various elements, such as magnesium and calcium, into liquid gray cast iron. As a result of alloying, the shape of graphite changes - it resembles a sphere and does not change the crystal lattice. It is worth considering that in its properties this metal resembles carbon steel and is used mainly in the manufacture of various wear-resistant parts.
6. Malleable. It is obtained by melting white cast iron, which should be heated to a high temperature and maintained in this state. In some cases, alloying elements are added to impart special qualities to the composition. The main properties include high viscosity and an increased degree of plasticity. Widespread in the engineering industry.
7. Special. It is an alloy that contains a large amount of manganese and silicon. It is often used to remove oxygen from steel during its production or remelting, thereby lowering the melting point.

Iron casting

Each type of cast iron has its own special structure and chemical composition, which determine the scope of application.

Due to its special physical and mechanical qualities, the use of cast iron has become possible in a wide variety of areas:

1. For the production of various parts in the mechanical engineering industry. For many years, this alloy has been used in the manufacture of a wide variety of parts for internal combustion engines. At the same time, automakers change the basic properties of the material by alloying it, which is necessary to achieve unique qualities. In addition, brake pads made of this alloy have become widespread.
2. Cast iron products can withstand low temperatures. Therefore, the material is used in the production of equipment and tools that are used in harsh climatic conditions.
3. Cast iron is valued in the metallurgical field. This is due to the low cost, which largely depends on the carbon concentration and the characteristics of the resulting structure. High castability also makes the material more attractive. The resulting products are characterized by high strength and wear resistance.
4. Over the past few decades, the alloy in question has been widely used in the manufacture of sanitary equipment. This is due to high anti-corrosion abilities, as well as the possibility of obtaining products of a wide variety of shapes. Examples include cast iron bathtubs and radiators, various pipes, radiators and sinks. Despite the emergence of materials that could replace cast iron, such products are very popular. This is due to the fact that they retain their original appearance over a long period of use.
5. The alloy is also used for the manufacture of various decorative elements, which is associated with high casting qualities. An example is a railing grid, various figurines and much more.

Cast iron frying pansCast iron radiators

In addition, the scope of application depends on the following properties of the material in question:

1. Some brands have high strength, which is characteristic of steel. That is why the material is used even after the advent of modern alloys.
2. Cast iron products can retain heat for a long period. In this case, thermal energy can be distributed evenly throughout the material. These qualities began to be used in the manufacture of heating radiators or other similar products.
3. It is generally accepted that cast iron is an environmentally friendly material. That is why it is often used in the manufacture of various dishes, for example, cauldrons.
4. High resistance to acid-base environments.
5. High hygiene, since all contaminants can be easily removed from the surface.
6. The material in question is characterized by a fairly long service life, provided that the operating recommendations are followed.
7. The chemicals included in the composition cannot cause harm to health.

In conclusion, we note that the long-discovered production technology of the material in question has remained virtually unchanged for many years. This is due to the fact that a large volume of molten alloy could be obtained at relatively low cost. Today, material is often produced from scrap, which makes it possible to further reduce the cost of the resulting product.

Source: https://stankiexpert.ru/spravochnik/materialovedenie/chugun.html

Cast iron - composition, properties and characteristics

The term “cast iron” can mean both a structural material based on iron and a metal vessel, a round pot for cooking. The latter is rare. Modern dishes are crowding.

The word “cast iron” is completely outdated. This is what the railway was called in the 19th and early 20th centuries.

What is cast iron

This is an alloy of iron and carbon with a carbon content of 2.14%. Ideally. In fact, in addition to those indicated, there are always impurities and alloying elements. So the distinction “floats”.

Depending on the carbon content relative to the eutectic, metal varieties are distinguished. Eutectic is the composition of an alloy with a minimum melting point.  

For cast iron, the carbon content is approximately 4.3%. Why “approximately” has already been said. Therefore, it is customary to divide cast iron into:

• hypoeutectic - 2.14 - 4.3% carbon;
• eutectic - 4.3% carbon;
• hypereutectic - from 4.3 to 6.67% carbon. 

Types of cast iron

In the generally accepted classification, they are divided according to the form of carbon they contain.

White

It is called so because of the characteristic color of the chip. Carbon C is contained in the form of cementite (formula Fe3C), which is formed when the melt cools. Hard refractory material.

In hypoeutectic alloys - in the composition of pearlite and ledeburite. In eutectic ones - in ledeburite. In hypereutectic - primary cementite and ledeburite.

In its original form, such cast iron is practically not used. Cannot be processed with high-speed steel tools. Only with carbide nozzles (VC), and even then with difficulty.  

It is used as a raw material for producing malleable.

Grey

Also named after the shade on the chip. Contains graphite fractions of various shapes. Carbon precipitation is facilitated by the addition of silicon.  

Properties and structure strongly depend on cooling conditions after crystallization.

Rapid cooling will give a predominance of perlite. Alloy of ferrite and carbide. A kind of “hardening” will increase strength and hardness. And fragility, which is not always acceptable.

Gentle cooling determines the increase in ferrite content. An alloy of iron with oxides, mainly Fe2O3. Plasticity will improve. Therefore, modes are selected based on the required parameters.

Gray cast iron is suitable for cast structures. It has a low curing temperature and good fluidity. Not prone to shell formation.

With all this, carbon inclusions cause low crack resistance. The material confidently withstands compressive forces, but is completely unsuitable for stretching/bending.

The marking indicates the symbols SCh and the ultimate strength in kg/mm2: SCh25. The most common cast irons are those with a C content below 3.7%.

Malleable

To produce white cast iron, it is heated to the required temperature, kept for a sufficient time and cooled slowly (“annealing”). The process provokes the decomposition of Fe3C with the release of graphite and the appearance of ferrite.

The shape of carbon inclusions is not similar to those in gray cast iron. This explains the appearance of some tensile strength and toughness.

Marked “KCh” with the addition of permissible tensile strength in MPa x 10-1 and maximum elongation. Example: CC 35-11.

High strength

A type of gray cast iron, only the graphite formations are shaped like balls. The roundness of the inclusions makes the crystal lattice not prone to cracks.

As a result, the initially valuable properties of cast iron (resistance to compression, ease of casting, etc.) are supplemented by a tensile yield strength comparable to steel, and crack resistance and ductility appear. 

They are marked similarly to malleable ones, but with the designation “HF”.

Peredelny

Used as a raw material for steel smelting. Often it does not even leave the enterprise where it was made.

Special

The production of such brands is small, up to 2% of the total volume. May contain significant amounts of alloying elements. Designed for limited purposes and specific conditions. Corrosion and chemically resistant ferroalloys are common.

One of the varieties is anti-friction cast iron. Used for the manufacture of rubbing parts. Alloyed primarily with chromium. Nickel, titanium, copper and others are also added.

It is characterized by high hardness (up to HB 300) and low coefficient of friction (up to 0.8 in the absence of lubricating emulsions).

Base materials: gray, ductile and high-strength cast iron. The markings are respectively AChS, AChK, AChV. The digital components are described above.

Advantages and disadvantages of the material

It is worth discussing in comparison with steel, although low-quality carbon steel is essentially the same as cast iron.

In some parameters (density, magnetic properties, typical chemical reactions) ferroalloys are almost identical. There are significant differences in the technology of use.

Advantages:

1. Moderate cost. Carbonation is part of the smelting process from ore. A decrease in its content will inevitably increase the price of the metal.

2. Excellent casting qualities. The melt is fluid. With low crystallization shrinkage, which minimizes defects. Relatively low melting point.

3. The products are durable, have a hard surface, and are wear-resistant.

4. The compositions used in mechanical engineering can be processed by cutting.

5. Durable. Including plumbing and sewer parts.

6. Items that have become unnecessary are easy to recycle. Any reception point with hands will be torn off.

Flaws:

1. Due to the high carbon content it is fragile. Not very suitable for pressure treatment. Certain brands produce forged products of excellent quality. But this is rather piece work and unprofitable on an industrial scale.

2. Welding is allowed only in extreme cases. The technology is quite complex, and the risk of defects is high.

3. The products are always massive. A thin-walled structure will not work, since it will not support its own weight and will not be able to be manufactured.

4. Easily oxidizes in a humid environment. It will not rust through due to its inevitable monumentality, but it will take on an unkempt appearance. Parts located outdoors require a corrosion-resistant coating.

Iron production

People mastered the rudiments of ferrous metallurgy already in the 2nd millennium BC. e. To obtain steel. But blast furnaces appeared in Europe only in the 14th and 15th centuries. Pig iron was obtained as a waste by-product.

They appreciated it when they noticed its outstanding casting qualities. It is convenient for making cannonballs, and it is also more convenient to obtain steel from it.

Technology reached Russia in a meaningful way in the 17th century. This happened under Peter I, when they were looking for material for weapons.

Iron ore is usually used as a raw material. The highest yield is obtained from magnetic and red, abundantly containing Fe.

Coke is used to maintain temperature. Combustion air is supplied forcibly. Flux (limestone) is designed to supply carbon dioxide. Main reaction:

.

The reduced Fe is lowered into the furnace, where it is saturated with carbon. The furnace operating cycle is continuous.

Getting steel

About 85% of cast iron is used for further steel production. An open hearth furnace is used for smelting.

During the melting process of the loaded raw material, a significant mass of FeO oxide is formed. As it heats up, the following reaction occurs:

.

Excess carbon is removed.

Electric arc and induction furnaces are also used. 

Areas of use

Due to the modern tendency to make equipment as light as possible, cast iron is used less and less. 

But there are areas where it is still indispensable and cost-effective:

1. In mechanical engineering it is used for large body parts with low tensile loads. Beds for machine tools, cylinder blocks for internal combustion engines. Flywheels, pulleys, gears, hydraulic cylinders, gear housings, electric motors, pistons.

2. Plumbing fittings, sewer pipes.

3. Decorative elements: fences, grilles, gates.

4. Stoves for houses, baths.

Source: https://nauka.club/materialovedenie/chugun.html

The concept of cast iron, its features and nuances of use

Cast iron firmly entered our lives many years ago. It is relatively easy to produce and widely used in various fields. To have a clear understanding of this material, you need to know its features, disadvantages, advantages, chemical composition, properties, structure of cast iron and its alloys, their production and scope of application.

So, let's find out which iron-carbon alloys are called cast irons.

Concept

Cast iron is an iron-carbon alloy containing carbon, that is, it means a material that consists of an alloy of iron and carbon. The percentage of carbon in cast iron is more than 2.14%. The latter element can be included in cast iron in the form of graphite or cementite.

This video talks about the features of cast iron:

There are white and gray cast iron.

• The carbon in white cast iron is in the form of iron carbide. If you break it, you can see a white tint. White cast iron is not used in its pure form. It is added to the process of producing malleable iron.
• At a fracture, gray cast iron has a silvery tint. This type of cast iron has a wide range of uses. It lends itself well to processing with cutters.

In addition, cast irons are high-strength, malleable and with special properties.

• High-strength cast iron is used to increase the strength of the product. The mechanical properties of such cast iron allow this to be done perfectly. High-strength cast iron is obtained from gray cast iron by adding magnesium to the mass.
• Ductile iron is a type of gray iron. The name does not mean that this cast iron is easily forged. It has increased plasticity properties. It is obtained by annealing white cast iron.
• There is also a distinction between half cast iron. Some of the carbon in it is in the form of graphite, and the remaining part is in the form of cementite.

Special Features

The peculiarity of cast iron lies in the process of its production. The average melting point of different types of cast iron is 1200ºC. This value is 300 degrees less than that of steel. This is due to the very high carbon content. Carbon and iron atoms do not have a very close connection with each other.

When the smelting process takes place, carbon cannot be completely incorporated into the iron lattice. As a result, cast iron takes on the property of brittleness. It cannot be used for the manufacture of parts that will be subject to constant load.

Cast iron is a ferrous metallurgy material. Its characteristics are often compared to steel. Products made of steel or cast iron are widely used in our lives. Their use is justified. After comparing the characteristics, we can say the following about these two materials:

• The cost of cast iron products is lower than the cost of steel ones.
• Materials vary in color. Cast iron is a dark matte material, while steel is light and shiny.
• Cast iron is easier to cast than steel. But steel is easier to weld and forge.
• Cast iron is less durable than steel.
• Cast iron is lighter in weight than steel.
• Steel has a higher carbon content than steel.

Advantages and disadvantages

Cast iron, like any material, has positive and negative sides.

The advantages of cast iron include:

• Carbon in cast iron can be in different states. Therefore, this material can be of two types (gray and white).
• Certain types of cast iron have increased strength, so cast iron is sometimes placed on the same line as steel.
• Cast iron can maintain temperature for quite a long time. That is, when heated, the heat is evenly distributed throughout the material and remains in it for a long time.
• In terms of environmental friendliness, cast iron is a clean material. Therefore, it is often used to make dishes in which food is subsequently prepared.
• Cast iron is resistant to acid-base conditions.
• Cast iron has good hygiene.
• The material has a fairly long service life. It has been noticed that the longer cast iron is used, the better its quality.
• Cast iron is a durable material.
• Cast iron is a harmless material. It is not capable of causing even slight harm to the body.

The disadvantages of cast iron include:

• Cast iron will rust if it is exposed to water for a short time.
• Cast iron is an expensive material. However, this minus is justified. Cast iron is very high quality, practical and reliable. Items made from it are also high quality and durable.
• Gray cast iron is characterized by low ductility.
• White cast iron is characterized by brittleness. It is mainly used for smelting.

Properties and characteristics

Cast iron has the following properties:

1. Physical . These characteristics include: specific gravity, coefficient of linear expansion, actual shrinkage. Specific gravity varies depending on the carbon content of the material.
2. Thermal . The thermal conductivity of a material is usually calculated using the displacement rule. For solid cast iron, the volumetric heat capacity is 1 cal/cm3*oC. If cast iron is liquid, then it is approximately 1.5 cal/cm3*oC.
3. Mechanical . These properties depend on the base itself, as well as on the size and shape of the graphite. Gray cast iron with a pearlite base is considered the most durable, and the most ductile is with a ferritic base. The maximum reduction in strength is observed with the “plate” shape of graphite, and the minimum – with the “ball” shape.
4. Hydrodynamic . Viscosity in cast iron varies depending on the presence of manganese and sulfur. It also increases sharply when the temperature of cast iron passes the point where solidification begins.
5. Technological. Cast iron has excellent casting properties, resistance to wear and vibration.
6. Chemical . According to the electrode potential (in decreasing order), the structural components of cast iron are arranged in the following form: cementite - phosphide eutectic - ferrite.

Differences between cast iron and steel in chemical composition and properties

The properties of cast iron are affected by special impurities.

• Thus, the addition of sulfur can significantly reduce fluidity and reduce refractoriness.
• The addition of phosphorus simultaneously makes it possible to create a product of complex shape, but does not give it increased strength.
• The silicon impurity makes the melting point not so high and significantly improves the casting properties. Different percentages of silicon create different types of cast iron, from pure white to ferritic.
• Manganese worsens casting and technological properties, but increases strength and hardness.

In addition to the mentioned impurities, cast iron may also contain other components. Then such materials will be called alloyed. The most common materials added to cast iron are titanium, chromium, aluminum, nickel and copper.

Next, you will find out what elements are included in the chemical composition of cast iron.

The video below will show you how to weld cast iron using electric welding:

If we consider cast iron as a structural material, then it is a metal cavity with graphite inclusions. The structure of cast iron is mainly pearlite, ledeburite and ductile graphite. Moreover, for each type of cast iron these elements predominate in different proportions or are absent altogether.

According to the structure of cast iron there are:

• perlite,
• ferritic and
• ferritic-pearlitic.

Graphite is present in this material in one of the forms:

• Globular. Graphite takes on this shape when magnesium is added. The spherical shape of graphite is characteristic of high-strength cast irons.
• Plastic. Graphite is similar to the shape of petals. In this form, graphite is present in ordinary cast iron. This cast iron has increased ductility properties.
• Flaky. Graphite acquires this shape by annealing white cast iron. Graphite is found in flake form in malleable cast iron.
• Vermicular. The named form of graphite is found in gray cast iron. It was developed specifically to improve ductility and other properties.

Metal production

Cast iron is produced in special blast furnaces. The main raw material for producing cast iron is iron ore. The technological process consists of reducing the iron oxides of the ore and obtaining another material as a result - cast iron. The following fuels are used to make cast iron: coke, natural gas and thermal anthracite.

Once the ore is reduced, the iron is in a solid form. Next, it is lowered into a special part of the furnace (steam), where carbon is dissolved in the iron. The output is liquid cast iron, which falls into the lower part of the furnace.

The price of cast iron (per 1 kg) depends on the amount of carbon in it, the presence of additional impurities and alloying components. Approximately the price of a ton of cast iron will be 8,000 rubles.

Cast iron is common in many areas.

• It is used for the production of parts in mechanical engineering. Engine blocks and crankshafts are mainly made from cast iron. The latter require advanced cast iron, to which special graphite additives are added. Due to the resistance of cast iron to friction, it is used to make excellent quality brake pads.
• Cast iron can operate smoothly even at extremely low temperatures. Therefore, it is often used in the production of machine parts that will have to work in harsh climatic conditions.
• Cast iron has proven itself well in the metallurgical field. It is valued for its relatively low price and excellent casting properties. Products made from cast iron are characterized by excellent strength and wear resistance.
• A large variety of plumbing products are made from cast iron. These include sinks, radiators, sinks and various pipes. Cast iron bathtubs and heating radiators are especially famous. Some of them still serve in apartments today, although they were purchased many years ago. Cast iron products retain their original appearance and do not require restoration.
• Thanks to its good casting properties, cast iron produces real works of art. It is often used in the manufacture of artistic products. For example, such as beautiful openwork gates or architectural monuments.

Are you choosing a bath? Don't know which is better, cast iron or steel? Then this video will help you:

Source: http://stroyres.net/metallicheskie/vidyi/chyornyie/chugun/ponyatie-osobennosti.html

What is steel and cast iron definition?

» Other »

Question for experts: How is cast iron different from steel?

Best regards, Daniel

Best answers

Briefly and in general terms, we can say that in terms of composition, cast iron differs from steel in its higher carbon content, in terms of technological properties - better casting qualities and low ability for plastic deformation. Cast iron is generally cheaper than steel.

Steel (Polish stal, from German Stahl) is a deformable (malleable) alloy of iron with carbon (and other elements), the carbon content of which does not exceed 2.14%, but not less than 0.022%. Carbon gives iron alloys strength and hardness, reducing ductility and toughness.

Considering that alloying elements can be added to steel, steel is an alloy of iron with carbon and alloying elements containing at least 45% iron (alloyed, high-alloy steel). Steel is the most important structural material for mechanical engineering, transport, construction and other sectors of the national economy. Steels are divided into for structural and instrumental steel Tool carbon steel is steel with a carbon content of 0.7% and higher.

This steel is characterized by high hardness and strength (after final heat treatment) and is used for the manufacture of tools. Tool carbon steel is divided into high-quality and high-quality. sulfur and phosphorus in high-quality tool steel - 0.03% and 0.035%, in high-quality - 0.02% and 0.03%, respectively.

According to the chemical composition, steels are divided into carbon and alloy; including by carbon content - low-carbon (up to 0.25% C), medium-carbon (0.3-0.55% C) and high-carbon (0.6-0.85% C); Based on the content of alloying elements, alloy steels are divided into low-alloy, medium-alloy and high-alloy. Cast iron is an alloy of iron and carbon (content more than 2.14%). Carbon in cast iron can be contained in the form of cementite and graphite.

Depending on the shape of graphite and the amount of cementite, there are: white, gray, malleable and high-strength cast irons. Cast irons contain permanent impurities (Si, Mn, S, P), and in some cases also alloying elements (Cr, Ni, V, Al, etc.). As a rule, cast iron is brittle. World production of cast iron in 2007 amounted to 953 million tons (including 477 million tons in China).

Depending on the carbon content, gray cast iron is called hypoeutectic (2.14-4.3% carbon), eutectic (4.3%) or hypereutectic (4.3-6.67%). The composition of the alloy affects the structure of the material. Cast iron includes an iron-carbon alloy that contains more than 2 percent carbon. In contrast, steel is an iron-carbon alloy consisting of less than 2.14 percent carbon, but with the presence of certain additives in the form of other elements.

Another distinguishing feature of steel from cast iron is that steel, depending on its grade, is subject to hardening, while cast iron cannot be hardened.

Cast iron is hard and brittle in its properties. It is not forged. Steel, unlike cast iron, lends itself well to forging, as well as welding, and in general to all common types of machining.

The listed characteristics are sufficient to determine the difference between steel and cast iron.

1.Cast iron is lighter than steel and has a lower melting point.2.Technological properties of steel can be processed (welding, cutting, rolling, forging), cast iron cannot be processed, so cast iron products are made only by casting.3.m carbon in steels 0.002-2.14%, in cast irons 2.14-6.67%4. Cast iron is the primary product of ferrous metallurgy, and steel is the final product.5.

Cast iron is not hardened, and some types of steel are necessarily subjected to a hardening procedure. 6. Structure, in particular the presence of ledeburite eutectic in cast iron. 7. Mechanical properties: Steels are more ductile and have high impact toughness, and cast irons, in turn, have higher hardness. The following difference follows from the mechanical properties: 8.

Application, in particular, unlike steels, cast irons are not used in the manufacture of parts operating under high cyclic dynamic loads.

9. Unlike steel, cast iron is divided not by the quantity and composition of impurities, but by the degree of freedom of graphite (iron carbide), if in a bound state it is white cast iron, in a free state it is gray.

answer

This video will help you figure it out

Answers from experts

Cast iron has a carbon content of 2 to 6%. I found this out on Wikipedia. I didn't find anything else there. Cast iron and steel consist of iron and differ from it in the presence of impurities. Cast iron differs from iron in that it does not deform.

This is the main advantage of cast iron. Cast iron is more brittle than steel, but easier to manufacture. I finally got to the main difference (in my opinion). Cast iron and steel differ in the method of hardening; for cast iron it is very simple, it is cooled sharply and that’s it.

I don’t remember how steel is hardened

Different percentage of carbon in the composition

One of the parameters is carbon content.
Ferrous is pure iron, rarely found in nature, steel is the strongest material currently existing, cast iron is an old, inelastic, rusting material.

There is no carbon in iron, but cast iron also contains a percentage of it that is higher than in steel!

iron is an ore that is mined and then processed into steel or cast iron. Steel is iron with a carbon content of less than 2.14 percent.

Cast iron is iron with a carbon content of more than 2.14 percent.

iron is any metal. cast iron is a heavy alloy of several metals.

steel or another metal can be stainless.

carbon content (percentage)

1.Cast iron is lighter than steel and has a lower melting point.2.Technological properties of steel can be processed (welding, cutting, rolling, forging), cast iron cannot be processed, so cast iron products are made only by casting.3.m carbon in steels 0.002-2.14%, in cast irons 2.14-6.67%4. Cast iron is the primary product of ferrous metallurgy, and steel is the final product.5.

Cast iron is not hardened, and some types of steel are necessarily subjected to a hardening procedure. 6. Structure, in particular the presence of ledeburite eutectic in cast iron. 7. Mechanical properties: Steels are more ductile and have high impact toughness, and cast irons, in turn, have higher hardness. The following difference follows from the mechanical properties: 8.

Application, in particular, unlike steels, cast irons are not used in the manufacture of parts operating under high cyclic dynamic loads.

9. Unlike steel, cast iron is divided not by the quantity and composition of impurities, but by the degree of freedom of graphite (iron carbide), if in a bound state it is white cast iron, in a free state it is gray.

Metals that vary in carbon content

Cast iron - an alloy of iron with carbon (content more than 2.14%)
Steel (Polish stal, from German Stahl) - a deformable (malleable) alloy of iron with carbon (and other elements), the carbon content of which does not exceed 2.14% , but not less than 0.022%. Carbon gives iron alloys strength and hardness, reducing ductility and toughness.

Same. The difference is in the additives in the chemical composition.

These are iron alloys with various metal additives. Steel contains more additives that improve the quality of the alloy, so steel is not susceptible to corrosion and is more durable than cast iron. Cast iron is rough steel.

from these types of Art. . Stainless steel is better. . after non-ferrous metals - second prize in the purchase

These are alloys))))) frying pans are made from))))

Cast iron - an alloy of iron with carbon (content more than 2.14%)
Steel (Polish stal, from German Stahl) - a deformable (malleable) alloy of iron with carbon (and other elements), the carbon content of which does not exceed 2.14% , but not less than 0.022%. Carbon gives iron alloys strength and hardness, reducing ductility and toughness

Source: https://dom-voprosov.ru/prochee/chto-takoe-stal-i-chugun-opredelenie

What kind of cast iron is steel made from?

Cast iron entered our lives many centuries ago and remains popular to this day . It has found wide application in many fields. However, in order to understand what cast iron is, it is important to know its properties and chemical composition, the structure and characteristics of its alloys, the advantages and disadvantages of this material, as well as its production and areas of application.

Chemical composition of cast iron

Cast iron is an alloy of iron and carbon, in which the percentage of carbon is not less than 2.14% but not more than 4.5%. Carbon is part of cast iron in the form of cementite or graphite. If the percentage of carbon content is less than 2.14%, the alloy is called steel.

It is known that cast iron alloy was first produced in China in the 6th century. The secret of its production came to Europe in the 14th century, and in Russia its composition was brought to perfection only in the 17th century. Over all this long time, the formula of cast iron has not changed.

The highest quality material was produced at the Demidov brothers foundry, located in the Urals.

Over the centuries, it not only has not lost its relevance, but has also acquired an even wider range of applications.

Types of material

There are such types of cast iron as limit and foundry. The first is used in the production of steel using the oxygen-converter route. Silicon and manganese are contained in very small quantities in this alloy. The casting type of material is more widely used in industry and manufacturing. It, in turn, is divided into the following types:

• White cast iron - the carbon in it is iron carbide. At the same time, a white tint is visible on its fault, which is where its name comes from. It is not used in its pure form. Used in the production of malleable cast iron.
• Gray cast iron is characterized by a silvery tint at the fracture. It has a wide range of applications and can be easily processed using cutters.
• A high-strength alloy is used to increase the strength characteristics of the manufactured material. It is obtained from gray cast iron by adding magnesium to its mass.
• Malleable cast iron is also a variety of gray cast iron. Its name indicates that it has increased ductility, and it is obtained from white cast iron by annealing.
• Half - has special properties. Part of the carbon in its composition is in the form of graphite, the rest is in the form of cementite.

Alloy features

The peculiarity of cast iron is hidden in the process of its manufacture. The fact is that for different types of this alloy the melting point reaches 1200ºC, while for steel it is 1500ºC. This factor is affected by too high a carbon content. Iron and carbon atoms do not have very close bonds with each other.

When smelting occurs, the carbon atoms cannot be completely embedded in the molecular lattice of the iron, causing the cast iron alloy to become brittle. In this regard, it is not used in the production of parts that will be constantly subject to load.

This material belongs to the ferrous metallurgy industry and its characteristics are similar to steel. Products made of cast iron and steel are widely used in everyday life, and it is entirely justified.

If we compare the characteristics of these metals, we can draw the following conclusions:

1. The cost of steel products is higher than the cost of cast iron.
2. Differences in color: cast iron is dark and matte, while steel is light and shiny.
3. Steel is less susceptible to casting, but, unlike cast iron, it is easier to forge and weld.
4. Steel has greater strength than cast iron alloy.
5. Steel is heavier in weight.
6. It has a lower carbon content than cast iron.

Advantages and disadvantages

This material, like any other, has its strengths and weaknesses.

The advantages of cast iron include the following factors:

• Sometimes it is even compared in terms of characteristics to steel, because certain types of it are characterized by increased strength.
• Retains temperature for a long time: when heated, heat is distributed evenly throughout it and remains unchanged for a long time.
• It is an environmentally friendly material, which is why it is often used in the manufacture of utensils in which food will be directly cooked.
• Does not react to acid-base environment.
• It is a durable material.
• The longer a product made from this material is used, the better its quality becomes.
• This material is absolutely harmless to the human body.

The disadvantages include the following factors:

• It can become rusty even if water is kept in it for a short time.
• It is a very expensive material, but despite this, it fully justifies itself. Quality, practicality and reliability are the main features of products made from this alloy.
• Gray cast iron is characterized by low ductility.
• White is very fragile and is most often melted down.

Characteristics and properties of cast iron

This metal alloy has the following properties:

1. Physical properties: specific gravity, actual shrinkage, linear expansion coefficient. For example, the carbon content of cast iron directly affects its specific gravity.
2. Thermal properties. Thermal conductivity is usually calculated using the displacement rule. For the solid state of a metal, the volumetric heat capacity is 1 cal/cm3*оС. If the metal is in a liquid state, then it is approximately equal to 1.5 cal/cm3*oC.
3. Mechanical properties. It is noteworthy that these properties are influenced both by the base itself and by the shape and size of the graphite. Gray cast iron with a pearlite base is the most durable, and with a ferritic base it is the most ductile. The lamellar form of graphite is characterized by the maximum reduction in strength, while the spherical form has the minimum reduction.
4. Hydrodynamic properties. The presence of manganese and sulfur in the composition affects the viscosity of the material. It also tends to increase when the temperature of the alloy passes the point at which solidification begins.
5. Technological properties. This metal is characterized by excellent casting qualities, as well as resistance to wear and vibration.
6. Chemical properties. As the electrode potential decreases, the structural components of the alloy are arranged in the following order: cementite - phosphide eutectic - ferrite.

The properties of the alloy are also influenced by special impurities:

• The addition of sulfur significantly reduces fluidity and reduces refractoriness.
• Phosphorus allows you to make products of various shapes, but at the same time reduces its strength.
• The addition of silicon reduces the melting point of the material and also significantly improves casting properties.

  silicon in different percentages makes it possible to obtain alloys of different colors: from ferritic to pure white.

• The presence of manganese in the alloy significantly increases the hardness and strength of the material, but at the same time its casting and technological qualities deteriorate.
• In addition to these impurities, the alloy may also contain other components.

  In this case, the materials are called alloyed. Most often, titanium, aluminum, chromium, copper and nickel are mixed with cast iron.

Source: https://MyTooling.ru/instrumenty/iz-kakogo-chuguna-poluchajut-stal