Steel Casting Plasticity And Toughness
General, low carbon steel ZG15 high melting point, poor casting performance, only used for the manufacture of motor parts or carburizing parts; the zg25~zg45, with high strength, Steel Casting good plasticity and toughness, is suitable for the manufacture of parts with complex shape, high strength and toughness, such as train wheels, Hammer Rack and anvil, roll and high-pressure valve, etc., Steel Casting is the most applied carbon steel in a class; The melting point of high carbon ZG55 is low, its casting performance is better than that of medium carbon, but its plasticity and toughness are poor, only used for making a few wear-resisting parts.
(1) Low alloy cast steel, China's main application of manganese, manganese, silicon and chromium series. such as zg40mn, ZG30MNSI1, Zg30cr1mnsi1 and so on. Used to make gears, Steel Casting hydraulic press cylinders and turbine rotors and other parts, and ZG40CR1 is often used to make high-strength gears and high-strength shafts and other important parts of the force.
(2) High alloy cast steel, with wear resistance, heat or corrosion resistance and other special properties. such as high manganese steel ZGMn13, it is a kind of anti-wear steel, mainly used for manufacturing parts used in dry friction working condition, such as grab front wall of excavator and track of grab tooth, Steel Casting tractor and tank, etc. chromium-nickel stainless steel zg1cr18ni9 and chromium stainless steel zg1cr13 and ZGCr28 etc, have high corrosion resistance to nitric acid , mainly used in the manufacture of chemical, petroleum, chemical fiber and food equipment parts.
The mechanical performance of cast steel is higher than that of cast iron, but its casting performance is worse than that of cast iron. Because the melting point of cast steel is higher, the steel liquid is easy to oxidize, the fluidity of the molten steel is poor, the shrinkage is big, the shrinkage rate is 10%~14%, Steel Casting the line shrinkage is 1.8% ~ 2.5%. In order to prevent the cast steel parts from pouring, cold insulation, shrinkage and shrinkage, crack and sticky sand, it is necessary to adopt the complicated technological measures than cast
1. Due to the poor fluidity of molten steel, Steel Casting in order to prevent cold isolation and insufficient pouring of cast steel parts, the wall thickness of cast steel can not be less than 8mm, and the structure of gating system is simple, and the cross-section size is larger than cast iron, the dry cast or hot cast is used, and the pouring temperature is generally 1520~1600℃, because of high pouring temperature, The fluidity of molten steel can be improved because of its high superheat and long liquid retention. Steel Casting But the pouring temperature is too high, will cause the grain coarse, the hot crack, the blowhole and the sticky sand and so on flaw. Therefore, in general, small, thin-walled and complex shape castings, the pouring temperature is about the melting point temperature of steel +150℃, large, thick wall casting temperature than its melting point of 100 ℃ or so.
2, because the shrinkage of cast steel is much more than cast iron, Steel Casting in order to prevent casting shrinkage, shrinkage defects, in the casting process, most of the use of riser and, iron and subsidy measures to achieve sequential solidification.