At what temperature does cast iron melt?

At what temperature does steel turn red - Metalworker's Handbook

Cast iron consists of carbon, iron and some impurities. It is one of the main materials of ferrous metallurgy. Cast iron is used in the manufacture of household and utility items, machine parts and in other industries. It is used in production, focusing and taking into account its properties and characteristics.

This article is precisely intended to tell you about the density of high-strength, liquid, white and gray cast iron, its melting points and specific heat capacity will also be considered separately.

Cast iron, like any metal, has the following properties: thermal, physical, mechanical, hydrodynamic, electrical, technological, chemical. Let's look at each properties in more detail.

This video talks about the structure and composition of cast iron alloys and the dependence of their properties on a specific composition:

Heat capacity

The thermal capacity of cast iron is determined using the displacement rule. When the heat capacity of cast iron reaches a temperature period, the beginning of which begins at a temperature whose value is greater than phase transformations and ends at a level equal to the melting temperature, then the heat capacity of cast iron takes on a value of 0.18 cal/Ho C.

If the value of the melting temperature exceeds the absolute value, then the heat capacity is equal to 0.23 ± 0.03 cal/Ho C. If the solidification process occurs, then the thermal effect is equal to 55 ± 5 cal. The thermal effect depends on the amount of pearlite when pearlite transformation occurs. Typically it takes a value of 21.5 ± 1.5 cal/G.

The volumetric heat capacity is taken to be the product of the specific gravity and the specific heat capacity. For solid cast iron this value is 1 cal/cm3*ºС, for liquid cast iron – 1.5 cal/cm3*ºС.

The specific heat capacity of cast iron is 540 J/kg C.

Specific heat capacity of cast iron and other metals in table form

Thermal conductivity

Unlike heat capacity, thermal conductivity is not determined by the displacement rule. Only if the amount of graphitization changes, the composition of the cast iron will affect the thermal conductivity.

Thermal diffusivity

The thermal diffusivity value of solid cast iron (for large calculations) can be taken equal to its thermal conductivity, and that of liquid cast iron – 0.03 cm2*/sec.

Read below about the melting point of cast iron.

Melting temperature

Cast iron melts at a temperature of 1200ºС. This temperature value is 300 degrees lower than the melting point of steel. With an increased carbon content, this chemical element has a close connection at the molecular level with iron atoms.

During the process of melting cast iron and its crystallization, the carbon component cannot completely penetrate the structural lattice of iron. As a result, the material cast iron takes on the property of brittleness. Cast iron is used for parts that require increased strength. However, cast iron is not used in the manufacture of objects that will be subject to constant dynamic loads.

The table below shows the melting point of cast iron in comparison with other metals.

Melting point of cast iron and other metals

Weight

The weight of the material varies depending on the amount of fixed carbon and the presence of a certain percentage of porosity. The specific gravity of cast iron at the melting point can be significantly reduced depending on the presence of impurities in the cast iron.

In addition, the linear expansion of the metal and the structure of cast iron changes depending on the state of each indicator. That is, these are dependent quantities.

The specific gravity of each cast iron differs depending on the type of material. Gray cast iron has a specific gravity of 7.1±0.2 g/cm3, white cast iron has a specific gravity of 7.5±0.2 g/cm3, and malleable cast iron has a specific gravity of 7.3±0.2 g/cm3.

The video below will tell you about some of the physical properties of cast iron:

The volume of cast iron, passing through the temperature of phase transformations, reaches an increase of 30%. However, when heated to 500ºC, the volume increases by 3%. Growth is aided by graphite-forming elements. Carbide-forming components inhibit volume growth. The same growth is prevented by applying galvanic coatings to the surface.

carbon is usually at least 2.14%. Thanks to the carbon content, cast iron has excellent hardness. However, the plasticity and malleability of the material suffers against this background.

We will talk about the density of cast iron below.

Density

The density of the described material, cast iron, is 7.2 g/cm3. If we compare other metals and alloys with cast iron, this density value is quite high.

Due to its good density, cast iron is widely used for casting various parts in industry. In terms of this property, cast iron is only slightly inferior to some steels.

Tensile strength

The compressive strength of cast iron depends on the structure of the material itself. The components of the structure gain their strength along with an increase in the level of dispersion. The tensile strength is strongly influenced by the number, size, distribution and formagraphite inclusions. The tensile strength decreases by a noticeable amount if the graphite inclusions are arranged in the form of a chain. This arrangement reduces the cohesion of the metal mass.

The tensile strength reaches its maximum value when the graphite takes on a spheroidal shape. This form is obtained without the influence of temperature, but when cerium and magnesium are included in the cast iron mass.

• When the melting temperature increases to 400ºС, the tensile strength does not change.
• If the temperature rises above this value, the tensile strength decreases.
• Note that at temperatures from 100 to 200ºС, the tensile strength can decrease by 10-15%.

  Cold-worked steel is

Plastic

The ductility of cast iron largely depends on the shape of the graphite, and also depends on the structure of the metal mass. If graphite inclusions have a spheroidal shape, then the percentage of elongation can reach 30.

• In ordinary gray cast iron, the elongation reaches only a tenth.
• In annealed gray cast iron, the elongation is 1.5%.

Elasticity

Elasticity depends on the shape of the graphite. If the graphite inclusions did not change, and the temperature increased, then the elasticity remains at the same value.

The elastic modulus is considered a conditional value, since it has a relative value and directly depends on the presence of graphite inclusions. The elastic modulus decreases if the number of graphite inclusions increases. Also, the elastic modulus increases if the shape of the inclusions is distant from the globular shape.

Impact strength

This indicator reflects the dynamic properties of the material. The impact strength of cast iron increases:

• when the shape of graphite inclusions is close to spherical;
• when the ferrite content increases;
• when the graphite content decreases.

Endurance limit

The endurance limit of cast iron becomes greater when the frequency of loading increases and the tensile strength becomes greater.

Dynamic viscosity

Viscosity becomes less if the amount of manganese in cast iron increases. A decrease in viscosity was also noticed with a decrease in the content of sulfur impurities and other non-metallic components.

The process is affected by the temperature value. Thus, the viscosity becomes less when the ratio of two temperatures is directly proportional (the temperature of the experiment and the start of solidification).

Surface tension

This figure is 900±100 dynes/cm2. The value increases as the amount of carbon decreases and undergoes significant changes in the presence of non-metallic components.

Toxicity

Cookware is often made from cast iron. The fact is that cast iron as a material is non-toxic and tolerates temperature changes well.

Electrical characteristics

The electrical conductivity of cast iron is assessed using Kurnakov's law. The electrical resistance of some types is given below:

• white cast iron - 70±20 Mk·oi·cm.
• gray cast iron - 80±40 Mk·oi·cm.
• malleable cast iron - 50±20 Mk·oi·cm.

According to the weakening effect on electrical resistance, the elements of solid cast iron can be arranged as follows: first - silicon, second - manganese, third - chromium, fourth - nickel, fifth - cobalt.

Technological features

Fluidity can be determined by various methods. This indicator depends on the shape and properties of cast iron.

Fluidity becomes greater when:

• overheating increases;
• viscosity decreases;
• hardening becomes less.

Fluidity also depends on the heat of fusion and heat capacity.

Chemical properties

The corrosion resistance of a material depends on the external environment and its structure. If we consider cast iron from the side of decreasing electrode potential, then its components have the following arrangement: graphite-cementite, phosphide eutectic-ferrite.

It should be noted that the potential difference between graphite and ferrite is 0.56 V. If the dispersion increases, the corrosion resistance becomes less. With a strong decrease in dispersion, the opposite effect occurs, and corrosion resistance decreases. Alloying elements also affect the resistance of cast iron.

Industrial cast iron contains impurities. These impurities greatly affect the properties, characteristics and structure of cast iron.

• Thus, manganese inhibits the graphitization process. The release of graphite is stopped, as a result, cast iron acquires the ability to bleach.
• Sulfur degrades casting and mechanical properties.
• Sulfides are mainly formed in gray cast iron.
• Phosphorus improves casting properties, increases wear resistance and increases hardness. However, against this background, cast iron still remains fragile.
• Silicon has the greatest influence on the structure of the material. Depending on the amount of flint, white and ferritic cast iron are obtained.

To obtain certain characteristics, special impurities are often introduced into cast iron during its manufacture. Such materials are called alloy cast iron. Depending on the added element, cast iron can be called aluminum, chromium, or sulfur. Basically, elements are introduced with the aim of obtaining a wear-resistant, heat-resistant, non-magnetic and corrosion-resistant material.

This video will compare the properties of cast iron and steel:

Source: https://ssk2121.com/pri-kakoy-temperature-stal-krasneet/

At what temperatures do various metals and non-metals melt?

Metals have a number of original properties that are unique to these materials. There is a melting point for metals at which the crystal lattice is destroyed. The substance retains its volume, but it is no longer possible to talk about the constancy of its shape.

Individual metals are found extremely rarely in their pure form. In practice, alloys are used. They have certain differences from pure substances. When complex compounds are formed, the crystal lattices combine with each other. Therefore, the properties of alloys may differ markedly from those of their constituent elements. The melting point no longer remains constant; it depends on the concentration of the ingredients included in the alloy.

Concept of temperature scale

Some non-metallic objects also have similar properties. The most common is water. A temperature scale was developed regarding the properties of the liquid that occupies a dominant position on Earth. The reference points are the temperature of changes in the aggregative states of water:

1. Transformations from liquid to solid and vice versa are taken to be zero degrees.
2. Boiling (vapor formation inside a liquid) at normal atmospheric pressure (760 mm Hg) is taken to be 100 ⁰C.

Attention! In addition to the Celsius scale, in practice temperature is measured in degrees Fahrenheit and on the absolute Kelvin scale. But when studying the properties of metal objects, other scales are used quite rarely.

In its ideal form, it is generally accepted that metals have a cubic lattice (real substances may have flaws). There are equal distances between molecules horizontally and vertically.

A solid substance is characterized by constancy:

• shapes, the object retains linear dimensions in different conditions;
• volume, the object does not change the amount of substance it occupies;
• mass, the amount of a substance expressed in grams (kilograms, tons);
• density, unit volume contains constant mass.

When transitioning into a liquid state, having reached a certain temperature, the crystal lattices are destroyed. Now we can’t talk about constancy of form. The liquid will take the form in which it is poured.

When evaporation occurs, only the mass of the substance remains constant. Gas will take up the entire volume that will be provided to it. Here we cannot say that density is a constant value.

When liquids combine, the following options are possible:

1. Liquids completely dissolve in one another, as do water and alcohol. The concentration of substances will be the same throughout the entire volume.
2. Liquids are stratified by density, the connection occurs only at the interface. It is only temporarily possible to obtain a mechanical mixture. Mix liquids with different properties. An example is oil and water.

Metals form alloys in the liquid state. To obtain an alloy, each of the components must be in a liquid state. With alloys, phenomena of complete dissolution of one in another are possible. Options cannot be excluded when the alloy will be obtained only as a result of intensive mixing. In this case, the quality of the alloy is not guaranteed, so they try not to mix components that do not allow obtaining stable alloys.

The resulting substances, soluble in each other, when solidified, form crystal lattices of a new type. Define:

• Heliocentered crystal lattices are also called body-centered. In the middle there is a molecule of one substance, and four more molecules of another are located around it. It is customary to call such lattices loose, since the bonds between metal molecules in them are weaker.
• Face-centered crystal lattices form compounds in which the component molecules are located on the faces. Metallurgists call such crystalline alloys dense. In reality, the density of the alloy can be higher than that of each of the components included in the composition (alchemists of the Middle Ages were looking for options for alloys in which the density would correspond to the density of gold).

Melting point of metals

Different substances have different melting points. It is customary to divide metals into:

1. Low-melting - it is enough to heat them to 600 ⁰C to obtain the substance in liquid form.
2. Medium-melting metals melt in the temperature range 600-1600 ⁰С.
3. Refractory are metals that can melt at temperatures above 1600 ⁰C.

The table shows low-melting metals in ascending order. Here you can see that the most unusual metal is mercury (Hg). Under normal conditions it is in a liquid state. This metal has the lowest melting point.

Table 1, melting and boiling points of fusible metals:

Table 2, melting and boiling points of medium-melting metals:

Table 3, melting and boiling points of refractory metals:

Various devices are used to carry out the smelting process. For example, blast furnaces are used to smelt iron. For melting non-ferrous metals, internal heating is carried out using high-frequency currents.

Molds made of non-metallic materials contain non-ferrous metals in a solid state. An alternating microwave magnetic field is created around them. As a result, the crystal lattices begin to loosen. The molecules of the substance begin to move, which causes heating within the entire mass.

If it is necessary to melt a small amount of low-melting metals, muffle furnaces are used. In them, the temperature rises to 1000-1200 ⁰С, which is enough for melting non-ferrous metals.

Ferrous metals are melted in convectors, open hearths and induction furnaces. The process involves the addition of alloying components that improve the quality of the metal.

It is most difficult to work with refractory metals. The problem is that you need to use materials that have a temperature higher than the melting point of the metal itself. The aircraft industry is currently considering the use of Titanium (Ti) as a structural material. At high flight speeds in the atmosphere, the skin heats up. Therefore, a replacement for aluminum and its alloys (AL) is needed.

The maximum melting point of this rather light metal attracts designers. Therefore, technologists are developing technological processes and equipment to produce parts from titanium and its alloys.

To design products from alloys, their properties are first studied. To study, the metals being studied are melted in small containers in different ratios to each other. Based on the results, graphs are built.

The lower axis represents the concentration of component A with component B. The vertical axis is temperature. Here the values ​​of the maximum temperature are noted when all the metal is in a molten state.

When cooled, one of the components begins to form crystals. In a liquid state, eutectic is an ideal compound of metals in an alloy.

Metallurgists identify a special ratio of components at which the melting point is minimal. When making alloys, they try to select the amount of substances used in order to obtain a eutectoid alloy. Its mechanical properties are the best possible. Crystal lattices form ideal face-centered positions of atoms.

The crystallization process is studied by studying the hardening of samples upon cooling. They build special graphs where they observe how the cooling rate changes. Ready-made diagrams are available for different alloys. By marking the start and end points of crystallization, the composition of the alloy is determined.

Wood's alloy

In 1860, American dental technician Barnabas Wood was looking for optimal ratios of components to produce teeth for clients at minimum melting temperatures. He found an alloy that has a melting point of only 60.268.5 ⁰C. Even in hot water, metal melts easily. It includes:

• tin - 12.512.7%;
• lead - 24.525.0%;
• bismuth - 49.550.3%;
• cadmium - 12.512.7%.

The alloy is interesting for its low temperature, but has never found practical application. Attention! Cadmium and lead are heavy metals and contact with them is not recommended. Many people can experience poisoning from contact with cadmium.

In practice, many people experience melting when soldering parts. If the surfaces of the materials to be joined are cleaned of contaminants and oxides, then they can be easily soldered with solders. It is customary to divide solders into hard and soft. Soft ones are most widespread:

• POS-15 - 278282 °C;
• POS-25 - 258262 °C;
• POS-33 - 245249 °C;
• POS-40 - 236241 °C;
• POS-61 - 181185 °C;
• POS-90 - 217222 °C.

They are produced for enterprises manufacturing various radio equipment.

Brazing alloys based on zinc, copper, silver and bismuth have a higher melting point:

• PSr-10 - 825835 °C;
• PSr-12 - 780790 °C;
• PSr-25 - 760770 °C;
• PSr-45 - 715721 °C;
• PSr-65 - 738743 °C;
• PSr-70 - 778783 °C;
• PMC-36 - 823828 °C;
• PMC-42 - 830837 °C;
• PMC-51 - 867884 °C.

The use of hard solders allows you to obtain strong connections.

Attention! Wed means that silver is used in the solder. Such alloys have minimal electrical resistance.

Melting point of non-metals

Non-metallic materials can be presented in solid and liquid form. Inorganic substances are presented in table. 4.

Table 4, melting point of inorganic non-metals:

In practice, organic materials are of greatest interest to users: polyethylene, polypropylene, wax, paraffin and others. The melting points of some substances are shown in table. 5.

Table 5, melting temperature of polymer materials:

Attention! The glass transition temperature refers to the state at which a material becomes brittle.

melting point of known metals.

Conclusion

1. The melting point depends on the nature of the substance itself. Most often this is a constant value.
2. In practice, it is not pure metals that are used, but their alloys. They usually have much better properties than pure metal.

Source: https://metmastanki.ru/temperatura-plavleniya-metallov-i-nemetallov-tablitsy

Melting point of iron and cast iron

The table shows the melting point of metals tmelt , their boiling point tk at atmospheric pressure, the density of metals ρ at 25°C and thermal conductivity λ at 27°C.

The melting point of metals, as well as their density and thermal conductivity are given in the table for the following metals: actinium Ac, silver Ag, aluminum Al, gold Au, barium Ba, beryllium Be, bismuth Bi, calcium Ca, cadmium Cd, cobalt Co, chromium Cr, cesium Cs, copper Cu, iron Fe, gallium Ga, hafnium Hf, mercury Hg, indium In, iridium Ir, potassium K, lithium Li, magnesium Mg, manganese Mn, molybdenum Mo, sodium Na, niobium Nb, nickel Ni, neptunium Np , osmium Os, protactinium Pa, lead Pb, palladium Pd, polonium Po, platinum Pt, plutonium Pu, radium Ra, rubidium Pb, rhenium Re, rhodium Rh, ruthenium Ru, antimony Sb, tin Sn, strontium Sr, tantalum Ta, technetium Tc, thorium Th, titanium Ti, thallium Tl, uranium U, vanadium V, tungsten W, zinc Zn, zirconium Zr.

According to the table, it can be seen that the melting point of metals varies over a wide range (from -38.83°C for mercury to 3422°C for tungsten). Metals such as lithium (18.05°C), cesium (28.44°C), rubidium (39.3°C) and other alkali metals have a low positive melting point.

The most refractory metals are the following: hafnium, iridium, molybdenum, niobium, osmium, rhenium, ruthenium, tantalum, technetium, tungsten. The melting point of these metals is above 2000°C.

Here are examples of the melting point of metals widely used in industry and everyday life:

• melting point of aluminum 660.32 °C;
• copper melting point 1084.62 °C;
• melting point of lead 327.46 °C;
• melting point of gold 1064.18 °C;
• melting point of tin 231.93 °C;
• the melting point of silver is 961.78 °C;
• The melting point of mercury is -38.83°C.

Rhenium Re has the maximum boiling point of the metals presented in the table - it is 5596°C. Also, metals belonging to the group with a high melting point have high boiling points.

The density of the metals in the table ranges from 0.534 to 22.59 g/cm 3 , that is, the lightest metal is lithium, and the heaviest metal is osmium. It should be noted that osmium has a density greater than that of uranium and even plutonium at room temperature.

The thermal conductivity of metals in the table varies from 6.3 to 427 W/(m deg), thus the worst conductor of heat is a metal such as neptunium, and the best heat-conducting metal is silver.

Melting point of steel

A table of melting temperature values ​​for common grades of steel is presented. Steels for castings, structural, heat-resistant, carbon and other classes of steels are considered.

The melting point of steel ranges from 1350 to 1535°C. The steels in the table are arranged in order of increasing melting point.

Source: https://crast.ru/instrumenty/temperatura-plavlenija-zheleza-i-chuguna

Brass: varieties and melting point

At what temperature does brass melt? Is it worth melting it at home? How does laser cutting of brass occur? These questions were asked by everyone who was faced with the need to make something from an alloy of copper and zinc. The speed of brass melting and the quality of the future product depend on the correctly selected temperature regime. To avoid damage to the material, read the useful information.

Where is brass used?

A non-ferrous metal such as brass is an alloy of copper and zinc (up to 50%) with possible impurities of a small amount of alloying elements. It has high thermal and electrical conductivity, density in the range of 8300-8800 kg/m3 and strength up to 600 MN/m2. Due to these qualities, as well as its attractive golden yellow color, brass is widely used:

• In art. Figurines and busts of famous figures are often made from this material, as it responds well to high temperatures. In addition, in the search for ideal forms, the finished sculpture can always be melted down.
• In interior and exterior design. Stylish light fixtures, mirror frames, and copper and zinc alloy countertops create a 1970s and mid-century modern feel while serving utilitarian functions. To prevent the alloy from blackening when exposed to air, the products are coated with protective compounds.
• In industry. The alloy of copper and zinc has a low coefficient of friction, so it is often used to cover the rubbing surfaces of bearings and other parts; mechanisms for land and water transport, fittings, etc. are made from it. Brass products
• In construction. Bronze and brass are resistant to corrosion, so products made from them can be used in conditions of high humidity. Shut-off and balancing brass fittings are common when installing water pipelines.

Types of brass

Depending on the composition of chemical substances, brasses are divided into:

• Two-component, or simple. Such alloys include mainly copper and zinc, the amount of other elements is insignificant. In turn, among them are:

1. Alpha brass, or single-phase. They contain less than 39% zinc, so there is no need to bring the melting point to 905 °C for it to dissolve into copper.
2. Beta brass, or two-phase. The second phase of brass occurs when the alloy contains more zinc than can be dissolved. As a rule, b-brasses are not as ductile as a-brasses, but are more durable.

classification of brass by chemical composition

• Multicomponent or special. They consist of copper, zinc and alloying elements such as iron, tin, silicon, aluminum, manganese and lead.

According to the degree and quality of brass processing there are:

• Deformable. For the manufacture of parts, such states of deformable brass as extra hard (with compression >50%), hard (with compression >30%), semi-hard (with compression 10-30%) and soft (annealed alloys) are used. A mixture of copper and zinc is presented in the form of round tubes, wire, tapes, sheets.
• Foundries. Cast brass is a low-melting variety that contains at least 50-80% copper, the rest is zinc and alloying elements. This includes the resulting brass products, as well as fittings.

At what temperature does brass melt?

Without knowledge of at what degrees brass melts and how to melt it, it will be impossible not only to cast parts from an alloy of copper and zinc, but also to laser cut brass. An incorrectly selected temperature for processing will lead to deterioration in the quality of the alloy and unnecessary energy consumption.

The melting point of brass is 880-950 °C. This indicator varies depending on the chemical composition of the alloy. The specific heat of fusion of brass does not coincide with the casting temperature. This is especially noticeable when melting lead brasses, which have reduced fluidity. The difference between their melting and casting temperatures is 145-185 °C.

For example, brass grade LS59-1V melts at a temperature of 900 ° C, but casting can be carried out at 1030-1080 ° C. For grades LS59-1 and LS74-3, these figures are 885-895 °C / 1030-1080 °C and 965 ° C / 1120-1160 °C, respectively, etc. For two-component brasses, the melting and casting temperatures are the same.

For example, for L60 it is 885-895 °C, L80 -965-1000 ° C, L96 - 1055-1070 °C.

The specific heat capacity of brass is 380 J/(kg °C). In other words, to heat 380 kg to a temperature of 1 °C, you need to spend 1 J of energy.

processing modes for simple and lead brasses

Please note: the more lead and bismuth in brass, the more difficult it will be to melt. Brass, which contains a large amount of zinc, melts most quickly. Alloys where the amount of this element reaches 32.5% can be processed without heating, using broaching or rolling.

Why is brass melting necessary?

As a rule, brass is melted before it is used to make fittings, condenser pipes, separators, worm screws, bushings, and other parts intended for use at high temperatures (up to 300 degrees Celsius).

Brass is melted to cast railings, cornices, door handles, decorative panels, frames for mirrors and paintings. Kitchen utensils can also be cast from this alloy: teapots, samovars, trays, bread bins, decorative dishes for hanging on the wall.

A mixture of copper and zinc is also useful for making souvenirs and jewelry.

Knowing how to melt brass, you can do this at home. In everyday life, bolsters, backplates, furniture and window fittings, etc. are cast from molten brass.

Melt brass at home

Equipment for melting brass at home is an induction furnace made of refractory materials, a crucible made of graphite or fireclay bricks, a foundry ladle, steel tongs and a volumetric spoon. Before melting the metal, the crucible must be heated for 20-30 minutes at a temperature of at least 95 °C. A spoon is needed to remove slag, tongs are needed to remove the crucible from the furnace, and a ladle is needed to support the crucible when pouring metal.

melting brass at home

To ensure safety, the ground should be covered with an asbestos sheet, and the molten metal should be carried to the molds strictly above the sand box. Special equipment is required. To avoid poisoning by toxic substances, the stove should be placed outdoors or in a well-ventilated area.

When the equipment is ready for use, the material to be melted is crushed and placed in a crucible, which is sent to the furnace. The crucible must remain in the furnace until the metal is completely melted. You can monitor this process through the window if the oven is factory-made, or by periodically lifting the refractory lid if the oven is homemade. Liquid brass is poured into a mold where it must cool before final processing.

You can also melt brass at home using a gas torch. To do this, it is placed under a container containing the crushed alloy. By uniformly heating the bottom of the container, you can achieve a liquid state of the metal.

Please note that during melting it is necessary to prevent the appearance of even small bubbles, which can spoil the quality of the future product. Molten metal cannot be stirred, even while removing slag from its surface.

Is it possible to solder brass?

Many beginners, as a rule, are concerned with the questions: can brass be soldered or not and to how many degrees can it be heated. The answer is clear: you can solder brass. It is quite possible to solder brass surfaces, although it will require more skill than when joining with conventional solder.

Solder for brass should consist of copper and silver, combined in a ratio of 1 to 2. Parts placed on an asbestos base are moistened with flux (borax, boric acid, water), sprinkled with crushed solder, then heated with a gas burner.

The temperature should not exceed 700° C to avoid deformation of parts; heating should be done gradually.

The difference between the melting temperatures of solder and brass parts does not exceed 50 °C, so if overheated, there is a risk of getting a large ingot instead of a quality product. If the work was done efficiently, the seam will have the same color as the brass surface of the part. This is explained by chemical diffusion. The last stage of soldering is removing flux residues. To do this, hot three percent sulfuric acid is used, which is then washed off the product with water.

Source: https://svarkaed.ru/svarka/poleznaya-informatsiya/latun-raznovidnosti-i-temperatura-plavleniya.html

10 interesting facts about metals and their amazing properties

Metals are a group of chemical elements in the form of simple substances. They all have their own properties, according to which they can be divided into different groups.

The word “metal” itself came into Russian from Germany. At first it meant the same thing as “mineral, ore.” They began to separate concepts only after Lomonosov’s works.

The word has entered the language remarkably well, now everyone knows it. The most famous metals are probably gold, silver, mercury, copper and iron. But knowledge even about them is very incomplete. Nature always finds something to surprise us with.

In this article we will look at 10 interesting facts about metals.

10. Titanium is used as an implant

Implantation is a way to restore lost teeth.
Now this method is very common due to its speed and accessibility. It consists of the following: a rod is implanted into the jaw, which becomes a support for the new tooth. This very rod is made of titanium.

As a metal, it has high strength, and its elasticity is similar to human bone, so implantation is easier. Titanium is the very basis of a dental implant, which reduces the risk of bone destruction .

9. Silver has bactericidal properties

Silver was known to people even before our era. For some time it was even valued higher than gold. However, people are still learning about its various properties.

For example, the direct effect of ionic silver on bacteria is still debated. It has been proven that when bacteria and ions come into contact, the former die as a result of exposure.

Many theories have already been put forward, but the exact reasons for the death of microorganisms under the influence of silver are still unknown.

The ions of this metal cope well with the pathogens of typhoid, protea, diphtheria and others . Where silver does not kill bacteria, it may slow the germination of new spores and the spread of microorganisms.

8. Tantalum is widely used in prosthetics

Tantalum is an unusual metal that is quite rarely found in its pure form. For this reason it became very expensive.

He is difficult to obtain, so he was named after the hero of Greek myths. There Tantalus constantly tried to get at least a little food and water, but he still failed.

A chemist trying to obtain this metal in its pure form compared his work to tantalum flour. Despite this, tantalum has now found application in many areas.

It is very widespread in medicine because the human body does not reject it . It is used to produce plates for skulls, paper clips for connecting blood vessels, threads for replacing tendons and stitching together fibers. Sometimes used to make eye prostheses.

7. Aluminum is part of the earth's crust

Immediately after its discovery, aluminum was highly valued due to its similarity to silver. And extracting it in its pure form was not easy.

Scientists have already proven that this metal is widespread everywhere. Almost 8% of the earth's crust consists of it .

If we compare metals by the amount of their content in the earth's crust, it is second only to oxygen and silicon. But here’s an interesting fact: despite its prevalence, aluminum cannot be found in nature in its free form.

6. Mercury evaporates into the air

When people first discovered mercury, it was given the name "living silver." This is a very accurate definition of what mercury looks like.

The rare metal is a liquid, but it is also very heavy. The most common item where you can see mercury is an old thermometer. All parents forbid their children to touch it. And all because of the properties of mercury, which can evaporate in the air .

The vapors generated during evaporation are very toxic and can harm the human body. They penetrate inside, disrupt the composition and structure of proteins, which is why some processes begin to flow in the opposite direction, which entails poisoning and death.

But only large amounts of this metal cause death, more than in a regular thermometer. However, measures to eliminate the problem must be taken immediately in any case.

5. Tin is the most fusible metal

One metal that has already revealed almost all its secrets to people is tin. It has been known to mankind for a long time.

Before the discovery of the properties of iron, almost everything was made from an alloy of tin and copper: from weapons to jewelry. And this is understandable.

Tin is one of the most fusible metals . Its temperature is 232 - 240 degrees Celsius. Thus, only one requirement must be met - for molds it should not melt at temperatures up to 250 degrees. That's all, this metal has no more restrictions for melting, casting, soldering and other uses.

4. Iridium is the densest metal

Iridium is an interesting metal. It is found in the earth's crust even less frequently than gold and platinum. There is an assumption that its quantity is much larger, but it is located closer to the Earth’s core, out of reach.

Relative to the earth's crust, iridium is often found in meteorites. It is the densest and most refractory metal .
Its melting point is 2466 degrees Celsius. In terms of density, it is comparable only to osmium. They are almost equal, and the difference in numbers can be attributed to an error.

3. The Valcambi company produces ingots from expensive metals in the form of chocolate bars

Valcambi is an organization in Switzerland that has taken a very creative approach to the concept of ingots.

When they say the phrase “gold bars,” people always imagine beautiful shiny bricks stacked on top of each other in a pyramid. But the company decided to destroy this idea.

They make gold, silver, platinum and palladium bars in the form of chocolate bars . This was a wonderful gift idea.

Such an ingot can be broken into several small pieces (about 1 gram) and given as a gift to loved ones. Another use case is to pay for purchases in stores that accept this type of payment, of course.

2. Olympic medals are not gold at all.

Olympic gold medals are silver . In fact, the International Olympic Committee has declared that gold sports awards must be plated with just 6 grams of gold.

The rest of the medals may be silver. So, for example, if you study a medal from the London 2012 Olympic Games, the research results will be quite surprising. gold in a gold medal is only 1%, although all conditions are met.

1. More than 50% of the world's gold is found in Africa

For as long as humanity has existed, people have been drawn to gold. Finding a vein meant untold riches. For his sake they lied, stole, killed. But using all the methods possible to us, about 161 thousand tons of it have been found throughout history.

Most of this expensive metal was discovered in South Africa . But in reality this is not as much as it might seem at the very beginning. It is easier to present this fact differently.

If you melt all the gold found in the world into one large cube, its side will be only 20 meters. Half of this cube was found in Africa. Approximately every hour people take out a cube of iron of the same size from the ground. And all the gold in the world is worth about 9 trillion dollars.

Source: https://top10a.ru/interesnye-fakty-o-metallax.html

At what temperature does titanium melt?

Titanium is considered the strongest refractory metal that retains its ductility. It is stronger than iron and aluminum. The alloy was first obtained by a Russian scientist in 1875. In 1925, a Dutch chemist managed to obtain 99.9% pure metal. Due to its high melting point, titanium is indispensable in the space industry and aircraft construction. Lightweight, chemically neutral, it is also used in other industries.

Characteristics of titanium alloys

Several components are used to alloy titanium:

• Aluminum is the most common additive. It increases specific strength, elasticity, and creep resistance.
• Tin slows down oxidation when heated, increases ductility and weldability.
• Thanks to zirconium, Ti-Al-Zr is deformable at room temperature.
• Manganese increases the ability to deform.
• Silicon improves crack resistance.
• Vanadium – weldability.
• The Ti-Al-Mo-Cr-Fe-Si system is highly durable. This is a martensitic metal.
• Molybdenum increases the heat resistance of titanium.

Pure titanium has a tensile strength of up to 450 MPa, alloying additives can increase it to 2000 MPa. When titanium cools, its flexural strength increases. At room temperature it is 700 MPa, around -200°C it increases to 1100 MPa.

Physical properties

Main characteristics of titanium:

• temperatures: melting 1668 degrees Celsius, boiling – 3227;
• yield strength: from 250 to 380 MPa;
• elasticity – 110 GPa, varies in different directions;
• the average hardness of alloys according to HB is 103;
• density: at room temperature 4500 kg/m3, at melting point - 4120 kg/m3;
• heat capacity – 531 J per kilogram when heated by a degree;
• thermal conductivity – 18 W/(m deg);
• resistivity – 42.1·10-6 Ohm·cm.

When cooled to 3.8°K (-270°C), the metal becomes a superconductor.

Application area

Titanium and alloys based on it are used in many fields: chemical, metallurgical. It is a structural material for astronautics, defense industry, and aviation. Medical instruments and equipment attachments are made from it. The plates are sewn into body armor and made into protective screens.

Source: https://svarkaprosto.ru/tehnologii/temperatura-plavleniya-titana

At what temperature does steel melt?

Steel is an alloy of iron mixed with carbon. Its main benefit in construction is strength, because this substance retains its volume and shape for a long time. The whole point is that the particles of the body are in a position of equilibrium. In this case, the attractive and repulsive forces between the particles are equal. The particles are in a clearly defined order.

• Melting temperatures of steel
• Stainless steel
• Cast iron and steel

There are four types of this material: regular, alloy, low-alloy, high-alloy steel. They differ in the number of additives in their composition. The usual one contains a small amount, and then increases. The following additives are used:

• Manganese.
• Nickel.
• Chromium.
• Vanadium.
• Molybdenum.

Melting temperatures of steel

Under certain conditions, solids melt, that is, they turn into a liquid state. Each substance does this at a certain temperature.

• Melting is the process of transition of a substance from a solid to a liquid state.
• Melting point is the temperature at which a crystalline solid melts into a liquid state. Denoted by t.

Physicists use a specific table of melting and crystallization, which is given below:

Substance	t,°C	Substance	t,°C	Substance	t,°C
Aluminum	660	Copper	1087	Alcohol	— 115
Voden	— 256	Naphthalene	80	Cast iron	1200
Tungsten	3387	Tin	232	Steel	1400
Iron	1535	Paraffin	55	Titanium	1660
Gold	1065	Mercury	— 39	Zinc	420

Based on the table, we can safely say that the melting point of steel is 1400 °C.

Stainless steel

Stainless steel is one of the many iron alloys found in steel. It contains Chromium from 15 to 30%, which makes it rust-resistant, creating a protective layer of oxide on the surface, and carbon. The most popular brands of this type are foreign. These are the 300th and 400th series.

They are distinguished by their strength, resistance to adverse conditions and ductility. The 200 series is of lower quality, but cheaper. This is a beneficial factor for the manufacturer.

Its composition was first noticed in 1913 by Harry Brearley, who conducted many different experiments on steel.

At the moment, stainless steel is divided into three groups:

• Heat-resistant - at high temperatures it has high mechanical strength and stability. The parts that are made from it are used in the pharmaceutical, rocketry, and textile industries.
• Rust-resistant - has great resistance to rusting processes. It is used in household and medical devices, as well as in mechanical engineering for the manufacture of parts.
• Heat-resistant - resistant to corrosion at high temperatures, suitable for use in chemical plants.

The melting point of stainless steel varies depending on its grade and the number of alloys from approximately 1300 °C to 1400 °C.

Cast iron and steel

Cast iron is an alloy of carbon and iron, it contains impurities of manganese, silicon, sulfur and phosphorus. Withstands low voltages and loads. One of its many advantages is its low cost for consumers. There are four types of cast iron:

• White - has high strength and poor ability to be processed with a knife. Types of alloy according to the increase in the amount of carbon in the composition: hypoeutectic, eutectic, hypereutectic. It was called white due to the fact that it has a white color in the fault. White cast iron also has a special structure of the metal mass and great wear resistance. Useful in making mechanical parts that will operate in a non-lubricated environment. It is used to make the following types of cast iron.
• Gray cast iron - contains carbon, silicon, manganese, phosphorus and some sulfur. It can be easily obtained and has poor mechanical properties. Used for the manufacture of parts that are not exposed to shock loads. There is a gray color in the fracture; the darker it is, the softer the material. The properties of gray cast iron depend on the temperature of the environment in which it is located and the amount of various impurities.
• Malleable cast iron is obtained from white cast iron as a result of simmering (prolonged heating and holding). The substance contains: carbon, silicon, manganese, phosphorus, and a small amount of sulfur. It is more durable and ductile, easier to process.
• Ductile iron is the strongest of all types of cast iron. Contains carbon, manganese, sulfur, phosphorus, silicon. Has high impact strength. This important metal is used to make pistons, crankshafts and pipes.

The melting points of steel and cast iron are different, as stated in the table above. Steel has higher strength and resistance to high temperatures than cast iron, temperatures differ by as much as 200 degrees. For cast iron, this number ranges from approximately 1100 to 1200 degrees, depending on the impurities it contains.

Source: https://respect-kovka.com/pri-kakoy-temperature-plavitsya-stal/

At what degrees does cast iron melt?

Cast iron melts at a temperature of 1200

Cast iron is an alloy based on iron and carbon. It differs from steel in the latter content – ​​2% or more. Some brands contain up to 4% carbon. Most often, an alloy with a carbon content of 3-3.5% is used.

This is a casting material. For such a metal, such properties as its melting point, as well as its thermal properties - heat capacity, thermal conductivity, thermal diffusivity - come to the fore. How different chemical elements affect the quality of this metal and whether it is possible to melt it yourself - this will be discussed in the article.

Thermal properties of cast iron

An important category of physical properties of a material is its thermal properties. These include:

• Heat capacity.
• Thermal conductivity.
• Thermal diffusivity.
• Thermal expansion coefficient.

They all depend on the composition, structure, and therefore on the grade of the alloy. In addition, these properties of the metal change with changes in its temperature (the so-called displacement rule). The nature of this dependence and the main physical properties are given in the table.

Heat capacity (s)

This is the amount of heat that must be supplied to the body in order for its temperature to increase by one Kelvin (hereinafter all values ​​are converted to degrees Celsius).

The heat capacity depends on the composition of the alloy, as well as on temperature (T). The higher T, the greater the heat capacity. If the temperature is above T for phase transformations, but below T for melting, then

at T exceeding the melting point:

c = 0.23±0.03 cal/(G˚С)

Volumetric heat capacity (the ratio of heat capacity to the volume of a substance) for approximate calculations is accepted:

• cast iron in solid state c' = 1 cal/(cm3G˚C)
• molten c' = 1.5 cal/(cm3G˚C)

Thermal conductivity (λ)

This is a quantitative characteristic of a body's ability to conduct heat. The displacement rule does not apply to thermal conductivity. The temperature of the material increases – λ decreases. It depends on the composition of the alloy, and to a greater extent on its structure. Substances that increase the degree of graphitization increase thermal conductivity, and substances that prevent the formation of graphite decrease it.

By the way, the thermal conductivity of molten cast iron is much less than that of solid cast iron. But due to convection it is greater than λ of the solid metal.

Thermal conductivity for different brands lies within:

λ =0.080.13 cal/ (cm·sec oC)

Thermal conductivity and other thermophysical properties depending on the temperature of the alloy are given at the end of the section.

Thermal diffusivity (α)

This is a physical quantity that shows how quickly body temperature changes. Equal to the ratio of thermal conductivity to volumetric heat capacity.

For approximate calculations you can take:

α=λ for solid metal (equal to its thermal conductivity);

α=0.03 cm2/sec for liquid.

What is it like?

The structure of cast iron is an iron base with graphite (carbon) inclusions. This material is distinguished not by its composition, but by the form of carbon in it:

• White cast iron (BC). Contains carbide (cementite) - this is a form of carbon, the same as in steel. It has a whitish color when scrapped. Very hard and brittle. In its pure form it is almost never used.
• Gray cast iron (GC). Contains carbon in the form of flake graphite. Such inclusions have a bad effect on the quality of the material. To change the shape of graphite grains, there are special methods of melting and further processing. Graphite in midrange can also be in the form of fibers (“worm-shaped” form) - the so-called vermicular graphite (from the Latin word vermiculus - a worm, like vermicelli).
• Highly durable. Spherical shape of graphite grains. It is obtained by introducing magnesium into the alloy.
• Malleable cast iron. To obtain it, warheads are annealed. Graphite grains in the form of flakes.

As a result, the main difference between it (apart from white) and steel is the presence of a graphite structure. And different forms of graphite determine the properties of different grades.

Conventionally, graphite grains are voids and cracks, and cast iron is steel riddled with microscopic cracks.

Accordingly, the more voids, the worse the quality of the metal. The shape and relative position of the inclusions also matters.

However, graphite grains should not be accepted as exclusively harmful. Due to the presence of graphite, this material is easier to machine and the chips become more brittle. In addition, it resists friction well also due to the graphite.

Impurities

Of course, this metal contains more than just iron and carbon. It contains the same elements as steel alloys - phosphorus, manganese, sulfur, silicon and others. These additives indirectly affect the characteristics of the alloy - they change the course of graphitization. The quality of the material depends on this parameter.

• Phosphorus. Has little effect on the formation of graphite. But it is still needed, because it improves fluidity. Solid inclusions of phosphorus provide high hardness and wear resistance of the metal.
• Manganese. It interferes with graphitization and, as it were, “bleaches” cast iron.
• Sulfur. Like silicon, it promotes bleaching of the metal, and also impairs fluidity. The amount of sulfur in the alloy is limited. For small castings no more than 0.08%, for parts more - up to 0.1-0.12%.
• Silicon. Strongly affects the properties of the material, increasing graphitization. The metal can contain from 0.3-0.5 to 3-5% silicon. By varying the amount of silicon, an alloy with different properties is obtained - from white to high-strength.
• Magnesium. Helps to obtain material with spherical grain shape. The boiling point of magnesium is low (1107˚C). For this and other reasons, introducing magnesium into the alloy is difficult. To avoid its boiling, the material is smelted using various methods of introducing magnesium.

In addition to the usual impurities, cast iron may contain other substances. This is the so-called alloyed material. Chromium, molybdenum, vanadium interfere with the process of graphite formation. Copper, nickel and most other substances contribute to graphitization.

Self-smelting technology

Non-industrial smelting of cast iron is a very labor-intensive process. It is impossible to smelt factory-quality castings with your own hands in artisanal conditions.

You cannot smelt this metal at home. You need a separate ventilated room - a garage, for example. Melting is carried out in furnaces. In industry, blast furnaces, cupola furnaces and induction furnaces are used.

A blast furnace is an industrial unit capable of melting metal on a huge scale. Iron ore raw materials can be smelted in it. After launch, it works without interruption for up to 5-6, or even up to 10 years. Then it is stopped, serviced and started again. Melting of the metal takes place in the presence of gases to improve the quality of the material. Such ovens are not suitable for small and medium-sized production. Fuel - coke.

A cupola furnace is a shaft-type furnace, like a blast furnace. It differs from the latter in that it does not maintain a special composition of gases. It is not ore that is smelted in it, but scrap iron. It is more suitable for small production.

An induction furnace is a modern type of equipment. The smelting process in such a furnace can be controlled, temperature, heating time and charge composition can be adjusted.

Melting is carried out in crucibles made of refractory clay or brick. Steel ones are not suitable, although steel begins to melt at a temperature higher than cast iron. Flux is required - a substance that promotes the formation of low-melting slag. For example, limestone (CaCO3), fluorspar (CaF2). To obtain gray rather than white cast iron, ferrosilicon (an alloy of iron and silicon) is added to the charge. It improves the formation of graphite grains. Once melted, the metal is poured into a sand or metal mold.

Metal casting is an explosive and fire hazardous job. In addition, it is necessary to have certain knowledge in the field of metallurgy. To organize production, you will need to complete documentation, pass inspections, obtain permission and a license to work.

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In industry and everyday life, cast iron products are widely used. The metal is iron, which has 2 percent carbon integrated into its molecular structure. Today, many grades of metal are produced that have different fracture characteristics. About a hundred species.

Production requires a huge amount of thermal energy, since the melting point of cast iron is over one thousand degrees Celsius. Melting occurs at a temperature of 1150 - 1200 C°.

In addition to carbon, to obtain the required grade, silicon, sulfur, manganese, and phosphorus are added to the batches. Increased strength is achieved by incorporating alloying additives into the batches.

Differences from steel

According to the technological process, cast iron is the primary product obtained by casting, and steel is the final product. The molecular structure of steel contains carbon in an insignificant amount. The material is plastic and lends itself well to mechanical processing. Products are manufactured by forging, welding, and rolling in mills. Has a high melting point. According to technology, steel is subject to hardening. The quality depends on the prepared mixture and on the melting temperature of the steels.

The rate of transformation of steel into a liquid state depends on various additives. A specific answer to the question at what temperature steel melts can be conditionally given only the heating range. The transition from a solid to a liquid consistency occurs at a temperature of 1450-1600 C°. The given digital parameter indicates the difference between steel and cast iron. These are different melting temperatures.

Cast iron is not as strong as steel. Cast blanks contain pores, making them brittle. It is during the casting process that cast iron products are produced. The presence of microscopic voids reduces the thermal conductivity characteristics of the metal. It is important to set the thermal regime, to record at what temperature cast iron melts.

Ferrous metallurgy produces several types of primary products. Let's look at some of them.

Grayish cast iron

Alloys formed by iron and carbon components change structure when integrating flake, flake, and fibrous graphite. Manufacturers obtain high-strength cast iron by adding globular graphite. The presence of Mg, Ce (magnesium, cerium) in the batch motivates its modification. Depending on how quickly molten cast iron cools, it acquires new consumer characteristics. Products of the required quality are obtained from a skillful combination of specific properties.

To make it easier to find the right material in catalogs, products are marked with the abbreviation S. Ch. The numbers following the letters indicate the force load limit in kilograms/per square millimeter. High-strength metal has the letter designation V.Ch. The numbers indicate the amount of strength, and also separated by a hyphen - the increase in length as a percentage. For example, HF60−1

Gray cast iron has excellent technological characteristics during its production process:

1. Crystallization does not require extreme temperatures, which has a positive effect on saving electricity and other types of energy.
2. Shows unique liquid fluidity.
3. When poured, it exhibits optimal shrinkage.

Due to its unique properties, metal is the base material for the production of products.

Has disadvantages in application. They manufacture units and parts that work only in compression. Machine beds, cylinders, various pistons, and so on are cast. Critical fragility indicators do not allow use for the production of products operating under conditions of bending forces. Melting point 1150 - 1260 C°

Bleached fabric colors

White cast iron contains an iron-carbon compound called cementite. It has colossal hardness, excluding plasticity. If you break a metal, the color is visible on the break. Cast iron is harder than stone and as fragile as eggshells.

Subjected to processing to obtain a malleable variety. The melting point occurs in the range of 1150 – 1350 C°. It is appropriate to note that the term malleable is used conditionally, since the metal cannot be processed plastically.

Malleable cast iron is produced by thermal firing.

Source: https://vi-pole.ru/chugun-plavitsja-pri-temperature-1200.html

How to melt cast iron at home - Metals, equipment, instructions

A smelter is a large or portable structure in which a quantity of non-ferrous metal can be melted. The induction melting furnace is widely known.

In production conditions, large quantities of induction melting furnaces are installed in special rooms to melt metal in large quantities. They melt metal from which many parts for motorcycles, cars, and tractors are cast.

To melt up to 5 kg of aluminum, you can build your own induction melting furnaces, solid fuel installations, and gas ones. They all work great. How and from what can you make a home melting pot?

We build our own smelting furnace

The installation for melting metal (Fig. 1) is assembled from bricks. It must be fireproof. Fireclay clay is used as a binder. To fire the device with coal, forced air is needed. For this, a special channel must be left in the lower half of the unit for air access.

A grate is located under this channel. This is a special cast iron grate on which coal or coke is laid out. The grate can be used from an old stove or purchased at the market or at a hardware store. For strength, some scald the finished structure with a metal belt.

The brick can be laid on its edge.

A smelting furnace cannot do without a crucible. You can use a cast iron cauldron instead. You can look for it on the farm. It will be good if it turns out to be enameled.

The crucible is installed closer to the burning coke. All that remains is to install a fan as forced air, light the coke and start smelting. The oven is ready with your own hands.

It can be used for melting cast iron, copper, bronze, aluminum.

Construction of a tabletop oven

From simple materials you can build gas or electric devices that fit comfortably on a table or workbench. To work you will need:

• graphite;
• mica;
• asbestos tiles;
• transformer;
• brushes from an electric motor;
• rods from an arc melting furnace;
• copper wire;
• nails;
• cement tiles;
• fire brick.

Asbestos has been banned for home use in recent years, so it can be replaced with tiles or cement. The sizes depend on the wishes of the owner. The power of the electrical network and the output voltage of the transformer play a big role here.

It is enough to apply a voltage of 25 V to the electrodes. For an industrial transformer used in welding work, this voltage is usually 50-60 V. In this case, the distance between the electrodes must be increased. Much is done by experience.

As a result, melting 60-80 g of metal is a good result.

It is better to make electrodes from brushes from a fairly powerful electric motor. They have a very convenient current supply wire. You can grind them yourself. There shouldn't be any big problems finding material.

In a homemade product, you need to drill holes on the side with a diameter of 5-6 mm, insert a copper stranded wire about 5 mm thick into them, and carefully hammer in a nail to secure the wire. All that remains is to make a notch with a file, it will help improve contact with the graphite in powder form.

The inside of the oven is lined with mica. This is an excellent heat insulator. The outside walls of the oven are reinforced with tiles.

To power the furnace, you can use a transformer that lowers the mains voltage to 52 V. The network winding is wound with 620 turns of wire Ø1 mm. The step-down winding is wound with a 4.2x2.8 mm wire having fiberglass insulation.

The number of turns is 70. The furnace is connected to the transformer with wires with a cross section of 7-8 mm² in good insulation. The finished installation must be turned on for a while so that all organic inclusions burn out. The oven was assembled by hand.

Metal smelting is carried out as follows:

• using a scoop or spatula, pour in graphite and make a hole in it;
• a material blank is placed in the hole;
• precious metals must be placed in a glass ampoule;
• tin and aluminum are placed in a separate iron cup;
• For alloys, the refractory metal is melted first, then the low-melting metal.

You cannot melt magnesium, zinc, cadmium, or silver contacts in such furnaces.

Cadmium burns out when melted, producing toxic yellow smoke.

When working with the installation, you must follow safety precautions:

1. Do not allow short circuits in the wires.
2. The power switch must be located near the operator.
3. Do not leave the device unattended during operation.
4. Nearby there is always a container filled with water in which the workpieces are cooled.
5. When melting cast iron and other metals, you must use safety glasses and gloves.

If desired, you can make gas installations. They are well suited for melting small batches of non-ferrous metal. Induction melting furnaces are capable of melting any metal.

They can be used as conventional installations for working with non-ferrous and precious metals, as melting and holding furnaces in production.

They are suitable for various needs: for heating metals, for making alloys of several metals, for melting cast iron.

Source: https://spb-metalloobrabotka.com/kak-plavit-chugun-v-domashnih-usloviyah/

Melting point of white cast iron

White cast iron is obtained by processing iron ores with a high manganese content. When fractured, this cast iron has a fine-grained or needle-like structure with a matte white color. All carbon, usually with a mass fraction of 6.67%, is in a chemically bound state in the form of cementite in the surface layers of the casting.

White cast iron is very brittle, practically impossible to cut, its hardness reaches 700.800 HB. Due to its high hardness and brittleness, white cast iron has no direct use as a structural material.

In some cases, the properties of high hardness and wear resistance of the structure of white cast iron (cementite) are created artificially in the surface layers of parts. This operation is called surface bleaching of parts and castings. The bleaching operation is achieved by a high cooling rate.

For example, in order to obtain high hardness, the surface of rolling mill rolls, plowshares, mill balls, diesel engine crankshafts and other parts are bleached to a depth of 5 mm.

The structure of white cast iron is unstable. At high temperatures, cementite decomposes into austenite and free carbon (graphite). The melting point of white cast iron is 1600 °C.

White cast iron is produced in the form of pigs weighing 40 kg, which are used for steel production in open-hearth and other furnaces, or in a liquid state (in this case, the cast iron is stored in special containers (mixers), from which it is then supplied to converters for steel production).

Half cast iron is low-grade white cast iron, in which part of the carbon is in a chemically bound state in the form of cementite, and part is in the form of free carbon (graphite) or mechanical mixtures, depending on the mass fraction of carbon (Fig. 4.7).

Thus, cast iron with a carbon mass fraction of 4.3% - eutectic - has the structure of ledeburite (a mechanical mixture of cementite and ferrite). Hypereutectic cast iron (more than 4.3% carbon) has the structure of pearlite + cementite + graphite.

Hypoeutectic cast iron (less than 4.3% carbon) has the structure of pearlite + ledeburite + graphite.

Half cast iron has very high mechanical properties, but it is brittle, so this cast iron is not directly used in foundries. Thanks to the presence in

Rice. 4.7. Microstructure of half cast iron:

1 - perlite; 2 - cementite; 3 - ledeburite

structure of free carbon, as well as unstable structures of ledeburite and cementite, half cast iron is a raw material for the production of malleable and special cast irons.

Today, cast iron is considered one of the most common metals. Parts for machinery and industrial equipment, building materials and much more are made from it. Before casting, you need to know the melting point of cast iron.

Types of cast iron

There are several types of cast iron. Various alloying impurities are added to it, which change the characteristics of the solid material. For this, aluminum, chromium, vanadium or nickel are used. In addition to them there are other impurities. The parameters of finished products directly depend on the composition of the alloy. Varieties:

1. Gray cast iron. It is considered the most popular type. The composition contains 2.5% carbon, which is a particle of graphite or perlite. Has a high strength index. Gray cast iron is used to make parts that can withstand constant loads. These can be gears, housing parts, bushings.
2. White cast iron. The carbon contained in the composition is carbide particles. A white mark remains on the fracture of the material, which corresponds to the name. carbon on average more than 3%. A fragile and brittle type of material, which is why it is used only in static parts.
3. Half-hearted. Combines the characteristics of the two previous types of cast iron. Graphite and carbide particles saturate the metal with carbon. Its content is from 3.5 to 4.2%. Wear-resistant material used in mechanical engineering. Withstands constant friction.
4. Malleable cast iron. It is obtained from the second type of material, after annealing. The alloy contains carbon in the form of ferrite particles. Its amount is about 3.5%. Like half-shaft, it is used for the manufacture of parts in mechanical engineering.

To obtain a high-strength material, graphite particles are processed so that they take on a spherical shape and fill the crystal lattice. Magnesium, calcium or cerium are added to the alloy.

Thermal properties of cast iron

The characteristics of a metal depend on its thermal properties. They change when treated with high and low temperatures. Directly depend on the composition of the alloy.

Source: https://MyTooling.ru/instrumenty/temperatura-plavlenija-belogo-chuguna