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August 12, 2017 18:08

High-strength cast iron and other representatives of the Specialty Alloys

Ductile Iron - is not the only representatively special alloys

smelted it in the blast furnaces of iron ore.The result is an alloy of iron with carbon and other components such as chromium or nickel.The alloy has high brittleness.The carbon in the iron is present as graphite or cementite.

graphite formation occurs in the process of its isolation from the molten alloy or by cementite decomposition.Its presence in the alloy increases the wear resistance of the metal.It is perfectly amenable to tooling, which process produces a clean surface.

Cast irons are mainly used only as a constituent of various alloys.High quality casting of metal contributed to its widespread use in the industry.Smelted in blast furnaces it for its intended purpose is divided into: steel making, casting and special (ferroalloy) types.The first two of them are used in further manufacture of steel.

Casting, whose production volume is about 20% of the produced iron available to plants for the production of machine-building industry of cast billets.Among the special alloys include heat-resistant, anti-friction, non-magnetic, wear-resistant and heat-resistant cast iron.Let us consider each of these in more detail in the next section.

heat-resistant cast iron - a bright representative of special alloys

heat-resistant cast iron is a type of gray high-strength alloys, alloying which made using silicon or chromium.This species differs metal resistant to high temperatures (up to 700-800oS).Also have a high heat resistance austenitic alloy cast iron, which include spheroidal graphite.

They are used in the manufacture of parts of various machines for the chemical industry, as well as turbochargers, which operate at temperatures up to 700 ° C.

Heat-resistant varieties are austenitic nodular CHN19HZSH.To improve the technological properties of these alloys subjected to annealing in the heating furnace, followed by tempering.As a result of this process in the metal structure are formed as rounded carbide inclusions.They are used for the manufacture of parts of diesel engines, various compressor equipment, etc.

Other special irons

Iron antifriction refers to gray ductile iron special stamps.These materials are characterized by low friction coefficient, which depends on the proportion of it ferrite and pearlite, as well as the shape and volume of graphite.Due to its metal base pearlite alloys are highly resistant to wear.

Durable cast iron is smelted using dopants such as nickel, chromium, molybdenum.Ready material is subsequently subjected to heat treatment, which leads to increased strength and durability of components.Also use surface hardening by high frequency currents to improve the performance of doped alloy.

Modified iron is obtained by adding to the liquid metal special modifiers.Some of them, such as magnesium or yttrium in certain concentrations cause selection of graphite, which contributes to the formation of a high strength material with nodular graphite.

All kinds of special alloys are widely used in various fields of engineering, particularly where high strength metal addition should possess certain specific qualities.