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August 12, 2017 18:08

White cast iron - an unusual kind of familiar material

white iron structure - what is the fundamental difference?Solubility

cementite (Fe3C, wherein the C content of about 6.5%) in the austenite (no chemical compound of carbon and iron, and the inclusion solution, wherein the free carbon incorporated into the crystal lattice of iron) classical state diagram zhelezotsementitnyh alloys (calculated by such diagramscomposition of the alloy phase at any given time temperature) is just over two per cent.

carbons in the iron may be present as cement and graphite.Graphite grain shape and with the ratio of their quantity of cementite (also the number and shape) define types of cast irons.

In composition, they may have additions of silicon, phosphorus, sulfur, manganese.Furthermore, since the brittleness sometimes used alloying aluminum, nickel, chromium or vanadium.It is obvious that with a change in the characteristics and composition, in the spectrum of iron alloys, hydrocarbons may be contained in a larger amount as lamellar graphite.And the color is gray kinks.Therefore, these varieties are called gray.

Such alloys of iron, carbon and silicon are also present sulfur, phosphorus and manganese.Unlike white alloy contains carbon in gray in free form.While the white iron structure contains carbon in the form of iron carbide.

As already mentioned, called white cast iron, which is dominated by carbon-related structures are ledeburite (as a kind of state of cementite melting point), perlite and cementite itself.This combination gives the material high hardness and brittleness, which complicates its direct use.From such applications include its use for the manufacture of splendid balls and cylpebs (cylinders) for crushing ore materials, rock, slag, clinker and other materials.

White and chilled cast iron - application

above-described white cast iron composition determines its high hardness, combined with the fragility of complicating the whole process workpieces by mechanical methods (cutting, milling, etc.) and require the use of special techniquessuch treatment (of the brands high-speed steel tools).In pure form, the use of white irons is rather limited.

industry produces a special, called pig, white cast iron, the use of which is specialized for melting into various steel.Normalization GOSTs defines a reduced content of silicon in its composition and additives higher concentrations of manganese.Such injection molding preform was prepared ways.

Depending on the degree of graphitization during smelting can be prepared a half, the transitional stage cast iron, these alloys are called chilled cast iron.This alloy contains in addition to iron carbides (chemically bonded carbon - Fe3C) graphitic carbon (free carbon - C).

And this cast iron is used as the friction parts dry friction mechanisms, such as the famous brake pads.Along with those, such alloys also characterized by high resistance to wear, so of them perform shafts and rolls in a rolling multi-purpose equipment.

additives and labeling of white iron

additional alloying white cast iron with chromium and nickel produces refractory materials with a fantastically high resistance to wear.They are called: wear-resistant.Such belohromisty doped iron used for casting details (e.g., blades and vanes of various pumping vehicles and turbines).

After casting billet obtained by heat treatment normalizes.The resulting products are of very high surface hardness, surprising stability to acids (even at temperatures of thousands of degrees Celsius).Furthermore

alloying chromium and nickel, a wear-resistant cast iron with special additives (in smaller quantities) may be copper, titanium, molybdenum, vanadium.Such additives impart the expected durability.Adding these elements to the structure allows some of these properties change depending on the destination, for use in machinery with high abrasiveness (mills, or peskomety drobomety, parts and valves for conventional and cement kilns).

This white cast iron marking can be carried out from the terminal (P, PL, PF, or PVC), which shows the mass fraction of silicon.For wear resistant cast iron (ICH and the IFC) will mark with the appropriate alphanumeric index.

As can be seen, hypoeutectic white cast iron is the raw material for many products industry.So, by annealing of it are ductile iron.Again, getting numerous alloy wear-resistant and heat-resistant materials are also conducted due to its proximity to the microstructure and properties of dopants.