Structure and properties of cast iron

187 
Gray cast iron is an alloy of Fе system - S-Si, containing in quality of impurity 
manganese, phosphorus, sulfur. Carbon in gray cast iron mainly is in a type of 
graphite of a lamellar form. 
According to SS gray cast iron mark the letters "G" - gray and "CI" - cast iron. 
The number after an alphabetic reference shows average value of strength of 
cast iron at stretching. For example, GCI 20-cast iron gray, strength at stretching 
of 200 MPas. 
On properties gray cast iron is possible to distribute conditionally on the 
following groups: 
- ferrite and ferrite-pearlite cast iron (brands GCI10, GCI15), apply to 
manufacturing of the low-responsible not loaded details of cars., 
- pearlite cast iron (brands GCI20, GCI25, GCI30), use for manufacturing of the 
wear-resistant details maintained at big loadings: pistons, cylinders, blocks of 
engines., 
- modified cast iron (brands SCh35, СЧ40, СЧ45), receive addition before a 
casting in liquid gray cast iron of additives, such cast iron have a pearlite metal 
matrix with a small amount of the isolated plates of graphite. 
Distinctive feature of high-strength cast iron are its high mechanical properties 
caused by existence in structure of spherical graphite. Cast iron with spherical 
graphite possesses not only high durability, but also plasticity. 
Receiving spherical graphite in cast iron is reached by modifying melt the 
additives containing Мg, Sa, Xie and other rare-earth metals. 
Chemical composition and properties high-strength cast iron are regulated by 
SS and marked by the letters "HS" - high-strength, ―CI‖ - cast iron and the 
number designating average value of strength of cast iron at stretching. For 
example, HSCI 100-high-strength cast iron, strength at stretching of 1000 MPas. 
High-strength cast iron with spherical graphite is the most perspective foundry 
alloy by means of which it is possible to solve successfully a problem of 
decrease in weight of designs at preservation of their high reliability and 
durability. 
High-strength cast iron use for manufacturing of responsible details in 
mechanical engineering (cranked shaft, cogwheels, cylinders, etc.). 
Malleable cast iron and alloyed cast iron. 
Malleable cast iron receive by annealing of white cast iron of the certain 
chemical composition, differing the lowered maintenance of graphitizes. 
Mechanical properties and recommended chemical composition of malleable 
cast iron are regulated by SS. Malleable cast iron mark the letters "M" - 
malleable, "CI" - cast iron and figures. The first group of figures shows strength 
of cast iron at the stretching, the second - its relative lengthening at a gap. For 
example, MCI 33-8 means: malleable cast iron with strength at stretching of 330 
MP as and relative lengthening at a rupture of 8 %. 

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For acceleration of process of annealing of MCI use various receptions: 
increase endurance temperature, modify and micro-alloyed cast iron additives of 
aluminum, pine forest, the titan and bismuth. 
Malleable cast iron use for manufacturing of small and average thin-walled 
casting of the responsible appointment working in the conditions of dynamic 
sign-variable loadings (a detail of driving mechanisms, transmissions, brake 
shoes, gear wheels, naves etc.). However malleable cast iron is a low-
perspective material because of difficult technology of receiving and duration of 
a production cycle of manufacturing of details from it. 
Depending on appointment distinguish wear-resistant, bearing, heat resisting 
and corrosion-resistant cast-iron. 
Wear resistant cast iron, alloyed by nickel and chrome apply to manufacturing 
of the details working in abrasive environments. Cast iron with addition of the 
titan, copper, vanadium posses the increased wear resistance in the conditions of 
a friction without lubricant. Them use for manufacturing of brake drums of cars, 
disks of coupling, sleeves of cylinders. 
Heat resisting cast iron apply to manufacturing of details of contact devices of 
the chemical equipment, turbo-compressor, maintained at temperature 600?С 
and 700?С. 
Corrosion-resistant cast-iron posses the increased corrosion firmness in gas, air 
and alkaline environments. They are applied to manufacturing of details of knots 
of the friction working at increased temperatures (piston rings, blocks and heads 
of cylinders of internal combustion engines.). 
Bearing cast iron are used as bearing alloys as represent group of the special 
alloys which structure satisfies to a rule of Sharpi, capable to work in the 
conditions of a friction as sliding bearings. 

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