Cast iron material standard
The materialistic characteristics and application scope of seven types of cast iron materials and machining cast iron material by the International Organization for Standardization (ISO) can be summarized as follows:
Ductile iron. Through cnc machining ductile iron and spheroidizing and inoculating molten iron, most or all of the graphite is spherical, and sometimes a small amount of it is flocculent cast iron. Ductile iron effectively improves the toughness, plasticity and mechanical properties of cast iron, and can obtain higher strength than carbon steel. Ductile iron is widely used in engineering parts with high tensile strength and elongation after fracture. Valves, crankshafts, steering knuckles, pumps, spindle housings, suspension parts, etc. can all be cast with ductile cast iron.
Gray cast iron. Gray cast iron machining generally does not require heat treatment, carbon is mainly precipitated in the form of flake graphite, and the fracture is dark gray when broken. Gray cast iron is the most widely used, and its output accounts for more than 80% of the total output of cast iron. Gray cast iron is generally widely used in general engineering parts, such as cylinder blocks, pumps, valves, clutch pressure plates, road tools, stamping tools, etc.
Malleable cast iron. Cast iron obtained by pouring molten iron with a certain chemical composition into a white blank, and undergoing graphitization or oxidative decarburization annealing. Malleable cast iron has high plasticity, strength and impact toughness. Malleable cast iron can be divided into white-heart malleable cast iron and black-heart cnc malleable cast iron, by reducing the silicon content to produce iron carbide, and then decomposing the carbide by heat treatment to form graphite. Malleable cast iron can be oil quenched and tempered for greater strength. Malleable cast iron has high toughness, strength and weldability, and universal joints, pipe fittings, suspension components, etc. can be made of malleable cast iron.
Vermicular graphite cast iron. Compacted graphite iron is a transition state cast iron between gray iron and ductile iron, and its properties are also intermediate between ductile iron and gray iron. Generally, heat treatment is not required unless stress relief is required. Vermicular graphite cast iron has high strength, good toughness, and good wear resistance. It can be applied to parts that require good thermal conductivity and higher strength than gray cast iron, such as brake drums and brake discs, ingot molds, cylinder liners, cylinder blocks, Hydraulic parts and so on can use vermicular graphite cast iron to complete casting processing.
Anti-wear cast iron. It is a cast iron with high wear resistance under certain wear conditions, and has good abrasive wear resistance. Anti-wear cast iron can generally be used for the processing of grinding balls, anti-wear liners of shot blasting machines, pump bodies for transporting liquid abrasives, valve bodies, excavator shovel teeth and other parts.
Austenitic cast iron. After smelting, it has a stable cast iron mainly composed of austenite matrix at room temperature. Austenitic cast iron has good heat resistance, alkali resistance, seawater corrosion resistance, acid resistance and non-magnetic properties. It can be used not only at low temperature but also at high temperature, and it still has good toughness even below zero. Parts that require corrosion resistance, heat resistance and non-magnetic properties can be made of austenitic cast iron, such as turbochargers, exhaust manifolds, refrigeration accessories, gas turbine casings, compressor casings, corrosion-resistant pump bodies, etc.
Austempering ductile iron. It is a cast iron material with ausferrite as the main matrix obtained by heat treatment of a certain composition of ductile iron. Austempered ductile iron has good ductility, high strength and good mechanical properties. Mainly used in gears, cams, excavator shovel teeth, crankshafts, wear-resistant iron tellurium, differential gears, railway vehicle wedges, speed dividers, track guides, etc., which require high strength, good toughness, fatigue strength and wear resistance tall parts.