Steel Casting Precaution
Steel Casting On the surface of the casting, all or part of the metal (or metal oxide) mixed with sand (or paint) or a layer of burning structure of the sand, resulting in rough casting surface, Steel Casting difficult to clean. Sticky sand occurs in the type, the core surface of the strong role of the site, sub-mechanical sand and chemical sticky sand two. The mechanical sticky sand is formed by the infiltration of molten metal into the pores of the surface of the casting. When the infiltration depth is less than the radius of the sand, Steel Casting the casting does not form sticky sand, but the surface is rough. When the penetration depth is larger than the sand radius, Chemical sticky sand is the product of the chemical action of the metal oxide and the molding material, and is firmly bonded to the casting.
Sticky sand precautionary measures:
(1) the use of refractors high sand, Steel Casting in order to improve the sand, core sand refractoriness, the original sand SiO2 content of 96% (mass fraction) above, and the sand should be thicker. The higher the pouring temperature of the cast steel, the thicker the wall thickness, the higher the content of SiO2 in the original sand.
(2) appropriate to reduce the pouring temperature and improve the casting speed, reduce the metal liquid on the sand of the thermodynamic and physical and chemical effects.
(3) sand compactness to be high (usually greater than 85) and uniform, Steel Casting reduce sand gap; type, core repair in place, can not have local loose.
(4) the use of high temperature does not crack, not sintered into the hole of the paint.
In general, low-carbon steel ZG15 has a high melting point, poor casting performance, used only in the manufacture of motor parts or carburizing parts; medium carbon steel ZG25 ~ ZG45, with higher than all kinds of cast iron comprehensive performance, that is, high strength, excellent Of the plastic and toughness, Steel Casting it is suitable for the manufacture of complex shapes, strength and toughness requirements of high parts, such as train wheels, forging hammers and anvils, rollers and high pressure valves, Steel Casting carbon steel is the most widely used class; High-carbon steel ZG55 low melting point, the casting performance is better than the carbon steel, but its plasticity and toughness is poor, only for the manufacture of a small number of wear parts.
According to the total amount of alloy elements, Steel Casting alloy cast steel can be divided into two low-alloy steel and high alloy steel category.
1) low alloy cast steel, China's main application of manganese, manganese and chromium and so on. Such as ZG40Mn, ZG30MnSi1, ZG30Cr1MnSi1 and so on. Used to manufacture gears, Steel Casting hydraulic presses and turbine rotor and other parts, and ZG40Cr1 commonly used to manufacture high-strength gears and high-strength shaft and other important force parts.
2) high alloy cast steel, with wear, Steel Casting heat or corrosion resistance and other special properties. Such as high manganese steel ZGMn13, is an anti-wear steel, mainly used in the manufacture of dry friction in the working conditions of the use of parts, Steel Casting such as the excavator grab the front wall and grazing teeth, Steel Casting tractors and tanks, etc .; chrome nickel stainless steel ZG1Cr18Ni9 and chromium stainless steel ZG1Cr13 and ZGCr28, nitric acid corrosion resistance is very high, Steel Casting mainly used in the manufacture of chemical, petroleum, chemical fiber and food equipment on the parts.