What types of cast iron are there?

Decoding the markings and grades of cast iron - Mandatory marking on the official website honest mark of the Russian Federation

In its usual understanding, a material such as cast iron is a fairly practical and cheap to manufacture product, which, by the way, has its own classification and labeling. At the same time, the indication of the brand can significantly influence the operational components of the material, ranging from its melting point to various areas of application.

A product can be characterized as cast iron only if it contains more than 2.14% carbon. Depending on its content and the addition of certain materials, specialists are able to make a workpiece so that it meets the requirements for further impacts, for example, in production, being a component of a machine.

Today we will tell you about the species diversity of cast iron as such. In addition, we will show the overall picture of how cast iron products should be marked and what designations may be encountered.

How is the marking of cast iron designated and deciphered?

Example of short designations for cast iron

One of the main advantages of cast iron is its widespread use as a casting alloy. Due to the characteristics of the material, almost anything can be made from it. Currently, these products are made everywhere, from automobile construction to serious military developments, for example, in tank building.

During the use of this material, metallurgical production came to the point that it modified the composition and made several of its varieties. This allows you to use the advantages of a particular brand in advance for specific tasks. In general, the following types and subtypes of cast iron are known today. We will look at them along with the markings.

Marking of gray cast iron

“SCh” – Gray cast iron is an alloy of silicon, iron and carbon. Moreover, the latter is in the composition in the form of graphite. When marking, according to GOST 1412-70, the letter “C” means gray , “C” means cast iron . When written, it usually occurs with numbers, for example SCH 00, SCH 12-28. In this case, the first numbers characterize the tensile bending strength .

At the same time, MFs are also divided into several groups, characterized by their properties and, as a consequence, the nature of their application:

1. Ferritic and Ferritic-pearlitic. These include products that have a tensile strength of 12-28 units and a bending value of 28-40. Used for the manufacture of minor parts without large load requirements: decorative columns, fittings, etc.
2. Perlite. MF 21-40 and 40-60. These types of cast iron are usually used in the production of heavy-duty parts, which during operation will be subject to significant dynamic loads and pressure. They are usually used to make: gears, piston heads, parts for machine tools, etc.
3. Steely. SCh 24-44 and SCh 28-48. It is made with the addition of steel and is used for parts experiencing sliding loads, such as stationary frames.
4. Modified. SCH 32-40 and 52-64. They are made by adding special additives to gray cast iron that improve certain characteristics of the material. If used correctly, you can get, for example, one that will crack less.
5. Antifriction (AFS). They are made for parts whose operation involves friction, such as plain bearings. There are also several varieties of them:
   1. AChS-1 and AChS-2 are used for working with hardened parts. The material differs from each other in composition.
   2. ASF-3 is used for other cases.

For example, if you see the marking of cast iron - SCH 12-28, then from it you can say that we have gray ferritic cast iron with 12 tensile units and 28 bending units.

Marking of ductile iron

In the production of high-strength cast iron, the addition of alkali and alkaline earth metals is used. Thanks to this, the metal base of the material is strengthened. The result is a workpiece that can withstand mechanical loads that carbon steel can withstand.

tensile strength , and the second shows elongation .

HF is used to produce parts and housings in heavy industry. In this case, you can also find anti-friction versions. In particular, at the moment there are AChV 1 and AChV 2, which means high-strength anti-friction cast iron.

Ductile iron marking

Malleable cast iron has found its application in areas that require high wear resistance and resistance to dynamic loads. In everyday life, these can be found even at home, for example: nuts, hooks, hubs, brackets, couplings.

This material is obtained by special temperature conditions and processing of white cast iron

According to GOST, the marking of this type of cast iron is usually indicated as “KCH”. In this case, there are also numbers indicating the tensile strength and relative elongation of the material.

Brief description of all brands and markings

If you do not need to study GOST and textbooks on metallurgy, then we will provide a brief description and instructions for selecting and deciphering a particular grade of cast iron. To begin with, you should know that cast iron is divided into 3 types:

1. Gray - This type of graphite is worm-shaped or plastic. It is marked as “SCh” (GOST 1412-85)
2. High Strength – Graphite has a spherical shape. Marked as “HF” (GOST 7293-85).
3. Malleable – Flaky model. Marked as “KCH” (GOST 1215-85).

Also, depending on the situation, for each type of cast iron products, conditions are provided for operation in constant friction mode. In this case, a model of anti-friction cast iron was additionally developed, marked as “ACh”. Depending on the type of material the AC is made from, a 3rd letter is added during the production process. For example, AChS - anti-friction gray cast iron or AChV (high-strength), etc.

Source: https://Vse-Markirovki.ru/vidy/rasshifrovka-markirovki-i-marki-chuguna/

What is white cast iron?

Among the brands of cast iron, white cast iron occupies a special place. Although, like all other types of cast iron, it contains carbon components, the amount of graphite compared to other types is much less, only about 0.3%. This property gives it a characteristic white shine and a distinctive grayish-white color at the fracture.

Types and composition of white cast iron

The classification of the material is carried out mainly according to two criteria - the physical structure of the metal and the composition of its components.

If we take a classification by composition, then we analyze the cementite eutectic - the internal structure of the material; it largely depends on the constituent chemical elements, namely carbon.

There are three categories of materials in this classification:

• A material in which the proportion of carbon does not exceed 4.3% is called hypoeutectic. This structure is formed after complete cooling. In turn, this category is divided into materials having a structure such as pearlite, ledeburite and secondary cementite;
• With a carbon content of 4.3%, the material belongs to the category of eutectic cast iron;
• Hypereutectic material contains from 4.3 to 6.6% carbon.

The second classification divides white cast iron into ordinary, bleached and alloyed.

Ordinary white cast iron is an alloy of two components - iron and carbon. In cross-section, it has a fine-grained structure; even despite high-temperature processing, this structure remains unchanged.

The class of white cast iron also includes bleached cast iron. The peculiarity of this alloy is that the basis for it is high-strength gray cast iron, and the surface layer, which includes a large amount of ledeburite and pearlite, gives it a characteristic white color. This effect is achieved by rapid cooling of the workpiece; the bleaching depth can reach 30 mm.

Alloyed types of white cast iron are divided into low, medium and high alloy grades. This division depends on the content of alloying components in the metal. In percentage terms it looks like this:

• Up to 2.5% additives – low-alloy grades of cast iron;
• from 2.5 to 10% – medium alloy white cast iron;
• over 10% – high-alloy white cast iron.

Adding alloying additives to the composition makes it possible to obtain a material with predetermined qualities and parameters. It should be noted that the additives used are the usual, most common additives used in metallurgy for the smelting of grade steels and cast irons.

Material properties, advantages and disadvantages

Like other types of cast iron, white cast iron has advantages and disadvantages characteristic of the entire type. Like other types of alloys, it has increased strength, but at the same time it also has increased fragility; it is very afraid of impacts.

The strengths of white cast iron include:

• excellent mechanical strength;
• increased resistivity;
• high wear resistance;
• ability to withstand high temperatures, including temperature changes;
• resistance to corrosion, including a large number of organic and inorganic compounds.

Alas, like most metals of this class, white cast iron is characterized by the following disadvantages:

• It makes castings poorly - during filling of molds it forms internal cavities and cracks, which significantly reduce the strength of the casting;
• the material has increased fragility - a sharp blow is enough for the workpiece to crack;
• the material is very poorly processed, it is poorly cut, milled, drilled and welded;
• alloy workpieces are subject to large shrinkage during cooling, it can reach 2%;

It is worth noting that this brand of cast iron does not weld well - when heated, microcracks form at the welding site, reducing the mechanical strength of the weld. In addition, such microscopic cavities increase even more as the workpiece cools.

Marking of white cast iron

According to the iron and steel brand, the alphanumeric code determines the characteristics of the material and the composition of alloying additives. Additional characteristics, such as wear resistance, are marked with the letter “I” in front of the code. The presence of spherical graphite in the composition is indicated by the letter “Ш”. The digital code indicates the presence of additional additives and impurities in the composition.

Application area of ​​white cast iron

High strength and the ability to retain shape at high temperatures have determined the use of the material in such industries as machine tool building, mechanical engineering, the production of machines and mechanisms for maritime transport, structural elements of machine tools, engines, and construction machines.

Alloyed types of cast iron are used in the automotive industry; individual engine parts are made from it. Alloyed white cast iron is indispensable in the mechanisms of mining machines.

The high strength has found its application in the form of rolling rolls for machines producing paper and cardboard. Mills, drive wheels and pulleys, balls for crushing crushed stone are all made of white cast iron.

Source: https://1nerudnyi.ru/belyj-chugun-10/

How to distinguish cast iron from steel at home

The development of industry and the creation of synthetic materials cannot detract from the advantages and benefits of traditional materials. These include cast iron and steel. These are some of the oldest familiar alloys to human civilization.

The technology of repair and design work often includes various types of processing. It could be:

• mechanical
• chemical
• thermal
• electrolytic
• plasma and other types of processing.

Despite the fact that cast iron and steel differ from each other by a tiny difference in carbon content, the methods and methods of influencing factors on these alloys differ and require different ways of the same method to influence the shape and structure of the metal.

Factors affecting the processing of steel and cast iron

In order not to waste money and resources, it is very important to know how to identify cast iron or steel.

• Selecting a welding electrode
• drill sharpening angle
• drilling and milling mode

These are not all the factors that can complicate the life and work of a person who incorrectly determines the type of metal. Reducing mechanical, strength and violating guaranteed repair intervals is a much greater evil that can damage production and the budget in the event of an error.     

Visual definition

How can you distinguish cast iron from steel visually without resorting to destructive testing methods? If there is a question about welding a cracked section of a part or even a piece that has fallen off, then it is possible to examine the breakdown or structure of the crack. The metal on a scrapped cast iron part will most likely be dark gray in color with a matte surface. Under the same conditions, the steel fracture will have a light gray, almost white color, with a glossy sheen.

The nature of cracks on the surface of high-carbon alloys is similar to a crack on pottery; low-carbon alloys are prone to plastic deformation and for this reason the crack has the shape of a rupture of plastic material.

Based on surface defects, only cast iron can be identified, which was poured into the mold at a low temperature, was not processed later, and a decorative paint layer was not applied. On such a product, hemispherical small grains are visible, formed due to non-shedding due to low temperature.

Don't forget about the correct visual method for identifying material. Soviet, modern and foreign GOSTs require the presence of material markings on all cast products. On domestic casting, the icons MF, HF, KCH - this means cast iron. L45, 45HL, 110G2S - indicates the use of steel casting for this element.

Mechanical determination by drilling

High-strength cast iron with nodular graphite is very similar in quality and visually to steel products. Testing a product by tearing it using a tensile testing machine is not entirely justified or reasonable.

To do this, you can select a non-working, inconspicuous area on the product and drill it not to the full depth with a drill of minimum diameter. The structure of cast iron is such that the chips are not able to form into a twisted loach. Graphite inclusions, even if they are not visible, crumble the chips at the stage of their formation.

Such shavings grind into dust in your hands and leave a black mark on your hands, like the lead of a simple pencil.

Steel shavings are capable of forming a loach longer than the length of the drill itself, and do not crumble in your hands. At high speeds it has a tarnished color on the surface.

Mechanical determination by grinding

You can approach the issue of determining the material using a grinder (angle grinder). As in the previous method, we select a section that is not a friction plane, contact pad or other important design element. With the machine turned on, we come into contact with the surface under study and monitor the shape and color of the sparks.

In cast iron products this will be a short spark with a reddish tint on the sprocket at the end of the track.

In metal products, the sheaf of sparks will be relatively larger, the tracks will be longer, and the sparks will be dazzlingly white or yellow.

If there is uncertainty and uncertainty in the method and your assessment, then you can take a known material, for example, a cast iron cauldron in the corner of the garage and check what sparks fly when processed with a grinder. At the same time, we should not forget that a number of special-purpose steels, especially heat-resistant ones, produce a spark of minimal size, with a short track and cherry red color.

This material does not cover methods exotic for home use:

• spectral analysis
• microscopic analysis
• weighing and volume determination.

But for home needs, the above methods are more than enough. Regardless of the method and method of determining the material, try to use diagrams, drawings and other information for your unit or product. The amount of information on the World Wide Web is off the charts and can reach the most remote corner of a workshop or garage.

Source: http://solidiron.ru/obrabotka-metalla/kak-otlichit-chugun-ot-stali-v-domashnikh-usloviyakh-bez-specialnykh-priborov.html

Why cast iron sewer pipes are still popular

Despite the fact that modern plastic pipe materials are in increasing demand, cast iron pipes do not lose their popularity. Cast iron sewerage is reliable, durable, resistant to temperature changes and pressure within the system. Cast iron pipes do not require additional sound insulation, are resistant to corrosion, and are available for self-installation.

Types of cast iron pipes and their applications

Cast iron is an alloy of iron with carbon additives. In order for an alloy to be called cast iron, its carbon content must be at least 2.14%. Iron alloys with a smaller proportion of carbon are steel.

There are several types of cast iron pipes, which are made from iron alloys with varying degrees of carbon content. Moreover, carbon varies not only in its fractional content, but also differs in structure. It can be round graphite, lamellar, chemically bonded carbon. In addition to carbon, aluminum, bismuth, nickel, chromium, manganese, sulfur, phosphorus, and silicon are added to the alloy to give the alloy certain chemical and physical properties.

Note! The high proportion of carbon in an iron alloy gives it increased rigidity and brittleness, reducing ductility. In terms of chemical properties, one can note increased resistance to aggressive influences, which significantly increases the service life of cast iron pipes (compared to steel counterparts).

The scope of application of cast iron pipe products remains quite wide, since for some operational characteristics these products have no equal analogues.

The main areas of use are:

• industrial pipelines for transporting aggressive liquids and petroleum products;
• construction of sewerage and drainage systems at industrial facilities and multi-storey residential buildings;
• installation of fire protection systems;
• heating and water supply.

In individual houses, they are rarely used for laying sewers, since there are no increased requirements for the strength of communications.

Cast iron pipes have the following performance characteristics:

• warranty service life 80 years;
• the minimum operating temperature reaches -60 degrees;
• withstand impacts from the internal environment with a force of 550 N/mm²;
• can be buried in the ground to a depth of 10 m;
• have the property of absorbing noise and vibration.

Note! An important advantage is the possibility of installation without the use of fittings, not only in straight sections. Long runs can be laid in an arc, connecting the pipeline segments into a socket.

The following types of cast iron pipes are distinguished:

• CHK – cast iron sewer, non-pressure. The composition of the alloy, in addition to carbon in plate form, includes silicon.
• VShChG – high-strength cast iron, pipes are designed for operation under conditions of high pressure, pressure.
• SML – cast iron pipe products without socket, an alloy with a high carbon content.
• ChNR - the abbreviation stands for “cast iron, pressure, socket”.

Gravity

Non-pressure cast iron pipes are used when laying indoor and outdoor sewerage systems in systems that operate by gravity. These are the materials that were used for sewer lines in residential buildings. Their advantage is noiselessness, the ability to combine with plastic pipes, and the possibility of reuse with careful dismantling. These are quite fragile products that cannot withstand shock loads.

High strength

High-strength cast iron is used for the construction of pipelines that operate under pressure for transporting aggressive liquids. A special feature of these materials is their resistance to force and impact loads. They are stronger than steel pipes. Their service life reaches 100 years or more.

Such strength of pipe materials made of VShChG cast iron is explained by the peculiarity of the alloy. It contains graphite in a spherical form, which gives the alloy a plasticity uncharacteristic of cast iron. Pipes are produced with a socket and rubber gaskets. In addition to industrial production, they are used for laying external sewerage in unfavorable conditions - at great depth, at extremely low temperatures, under highways.

Socketless

Pipe products that require special clamps for installation. To make socketless cast iron pipes more corrosion resistant, they are coated inside and outside with a special compound containing epoxy resin. The scope of application of these products is drainage systems in enterprises using aggressive media and water supply.

For the installation of water pipes, socketless cast iron pipes have no equal. These are environmentally friendly pipelines with high throughput that can withstand any temperature and its changes. According to statistics, such water supply systems have the longest trouble-free service life.

Flared pressure

During production, these pipes are coated with a special bitumen-based composition, which gives them additional resistance to aggressive influences.

Dimensions of cast iron pipe products

Pipe products made of cast iron are characterized by the following dimensional parameters:

• product wall thickness;
• nominal bore (not to be confused with internal section);
• external diameter.

The weight of a linear meter of a product is not used as a characteristic of a cast iron pipe, since it varies depending on the size and type.

The official document that regulates the production of non-pressure pipe products made of cast iron is GOST 6942-98. According to this document, products are produced in three external diameters - 50, 100 and 150 mm.

To regulate the production of pressure pipes, GOST 9583-75 is used. According to it, pipes with a nominal bore from 65 to 1000 mm are manufactured.

Based on wall thickness, pipes are divided into 3 classes marked A, B, LA. These characteristics are systematized in special tables.

Due to the high mass of products, cast iron pipes are produced in segments from 0.75 m to 6 m in length.

Note! When specifying the length of the product, the socket is not taken into account.

Marking

When choosing cast iron pipe products, you should pay attention to their markings, which indicate all the parameters of the pipe, starting with its type, namely:

• type of product;
• production standard;
• length;
• conditional capacity.

For example, the marking ТЧК-150-2000 GOST 6942-98 designates a bell-shaped non-pressure product with a diameter of 150 mm and a segment length of 2 meters.

Advantages and disadvantages

The popularity of cast iron pipes for sewer installation is explained by their high wear resistance. The main positive qualities of communications include:

• long trouble-free service life, which reaches up to 100 years;
• environmental safety;
• noiselessness;
• possibility of installation in any soil without the use of additional protective boxes;
• possibility of installation at great depths;
• possibility of combination with modern plastic pipes;
• low cost of maintenance of communications after commissioning;
• resistance to temperature changes and low temperatures;
• a wide range of installation possibilities - socket connections, welding, using fittings or special clamps.

The disadvantages of cast iron sewer pipes include:

• fragility;
• heavy weight;
• high cost.

Note! The fragility and heavy weight of cast iron pipes make them difficult to install and transport independently. When purchasing sewerage products for an individual home, you should choose pipes with a thin wall.

Cast iron socket products of class A or LA have sufficient strength for an individual sewer system.

Installation of a sewer system made of cast iron pipes

For installation of sewerage inside the house, socket-type non-pressure products with a diameter of 50 or 100 mm are used. For laying external communications, the pipe diameter increases to 150-200 mm. However, these dimensions are not a rigid norm and vary depending on the purpose of the sewer system and the expected throughput load.

Vertical installation of sewer sections is carried out in a socket, assembling the structure from the bottom up. To seal the joints, use internal rubber gaskets and additionally seal the joint with mortar or a special sealant (construction sealant dries faster). The solution is left for a day to dry, after which a test launch of communications is carried out.

Note! Pipes and fittings manufactured before 1974 are not standardized and may differ in size from newer ones. Currently, cast iron pipes and fittings are produced according to international standards.

For installation of turns, wiring, revisions, appropriate fittings are used, which can be bell-shaped or smooth. Plumbing manufacturers offer a large selection of tees, crosses, bends, and adapters for cast iron pipelines.

Fastening of cast iron communications is carried out on special supports, to which the pipes are attached with circular clamps and brackets.

Source: https://InfoTruby.ru/material/chugunnye-truby

All about cast iron: types, markings, classification

Cast iron is a very durable material that can withstand different climatic conditions. This metal is used to make dishes, heating radiators and much more. It is used in industry, as well as other spheres of life. There are several types with specific features and characteristics. Next, we will consider the varieties, classification, decoding of markings and how many types of cast iron there are.

What is cast iron?

Cast iron is an alloy of iron and carbon. Like any other metal, it has its positive and negative sides:

1. Has a tendency to rust with prolonged contact with water.
2. It has durability, strength, quality, elasticity, reliability and practicality.
3. Depending on the type, it may have reduced ductility as well as fragility.
4. Environmentally friendly material, harmless to humans and animals.
5. The alloy has a long service life (more than 50-60 years).
6. It has a high level of hygiene, as well as high resistance to acid-base environments.
7. Has excellent thermal conductivity.
8. Similar in quality characteristics to steel, it has a special level of strength.

Properties

• Physical (these include shrinkage, specific gravity, linear expansion coefficient).
• Thermal (1 cal/cm3*оС or 1.5 cal/cm3*оС).
• Mechanical (have a direct dependence on the shape, size and base of the graphite included in the composition - this is ductility and strength).
• Chemical (arrangement of elements according to electrode potential).
• Hydrodynamic (depending on the amount of manganese and sulfur in the alloy).
• Technological (responsible for vibration resistance).

Main features

• It has a melting point of 1200 degrees Celsius, which is 300 units different from steel.
• Due to the lack of a strong bond between carbon and iron in the composition, such material is not used for the manufacture of various parts, since it cannot withstand heavy loads.
• The metal belongs to the products of ferrous metallurgy.
• The properties are greatly influenced by various impurities in the composition - manganese, phosphorus, sulfur, silicon, titanium, chromium, aluminum, nickel, copper.

Classification of cast irons

The classification of cast iron is determined in accordance with the established technical standards GOST 3443-77. Its division occurs according to characteristics. According to carbon status:

By inclusion of graphite:

1. Flaky.
2. Globular.
3. Vermicular.
4. Lamellar.

By matrix:

1. Ferritic.
2. Pearlitic.
3. Ferrite-pearlite (mixed).

By chemical composition:

1. Alloyed.
2. Not alloyed.

Varieties

1. White. An alloy where carbon is contained in the form of cementite. This allows you to obtain a white color and metallic luster of the product. It contains a very small amount of graphite, which is revealed using the magnification method. This variety has a number of advantages. Among them are wear resistance, resistance to corrosion and rotting. With increasing carbon in the composition, the hardness of the material will increase.

   Among the disadvantages, there is poor mechanical processing, which is why it is also called conversion.

2. Grey. There is carbon (plate-shaped graphite) and silicon with admixtures of manganese, sulfur and phosphorus. There is a shade of gray inside. Another variety is gray cast iron with spherical graphite and magnesium and cerium in its composition. This is an excellent option for casting. It is also called foundry.

   It has fluidity, low crystallization temperature and low shrinkage. If graphite is present in the composition, then this metal is only suitable for compression work. Graphite imparts fragility and brittleness, which prevents the manufacture of parts from it. Like other types, it has designations and strength limits (SF).

3. Malleable. This variety is distinguished by the special softness and viscosity of the metal.

   When casting it, a white alloy is used, which is subjected to heat treatment. This process is called annealing, where graphitization of graphite takes place. It has special strength, resistance to impacts and damage. It is widely used for the manufacture of parts, especially automotive parts (brake pads, balls, axles). It has designations (CC) and strength limits (indicated next to the letters).

   These indicators are contained in specially developed technical regulations (GOST). The production of cast iron of a certain type is carried out exclusively on the basis of accepted rules.

4. Highly durable. This variety contains graphite. It has a spheroidal shape. This makes it possible to achieve high metal strength.

   Used for the manufacture of pipes for various purposes (water supply, drainage, oil pipelines). They have a long service life and performance properties.

Areas of use

There are many areas of application of cast iron. This situation has arisen due to the various types and classifications of this metal. This:

1. Heavy industry (production of parts and various items in metallurgy and machine tool building).
2. Mechanical engineering (gray cast iron is usually used, as it has useful properties - resistance to vibrations and vibrations).
3. Automotive industry (both metal is used in its pure form and mixed with graphite for the manufacture of cylinders, crankshafts and other elements).
4. Brake pads used in various spheres of life (flour-grinding industry, paper-making industry).
5. For the production of household and household utensils - cauldrons, frying pans, pots and other utensils (does not cause allergic reactions, retains heat well and does not oxidize).
6. In art (these are forged and cast fences, gates, monuments and decorative items).
7. In the oil industry (pipes and other products made of cast iron in this industry are characterized by durability and excellent performance properties).
8. For the manufacture of bathtubs and sinks (service life more than 50-60 years).

The production of cast iron is carried out exclusively on the basis of special technical instructions, which specify the properties, grades and characteristics.

All about cast iron: types, markings, classificationLink to main publication

Source: https://oxmetall.ru/metalli/chugun/vidy-markirovka-klassifikatsiya