Steel Casting Casting Characteristics
One of the advantages of steel casting is the flexibility of design. The design personnel have the maximum design freedom for the shape and size of the castings, especially the complex shape and the inner parts of the hollow section. The cast steel can be made by using the unique process of the stamen. Its shape and shape change is very easy, from the pattern to the finished product conversion speed is very fast, it is advantageous to the quick quotation response and the delivery time shorten. The characteristics of the shape and quality of the perfect design (state of the art), the minimum stress concentration coefficient and the overall structure are all reflected in the flexibility and technological advantages of the design of the cast steel:
1) the metallurgical manufacturing adaptability and variability of the cast steel components can be used to select different chemical components and organizational control to adapt to the requirements of various engineering projects; The mechanical properties and performance can be selected through different heat treatment processes, and have good welding performance and machining performance.
2) the overall structural strength of cast steel materials and steel castings is strong, thus improving the engineering reliability. Combined with the advantages of reducing weight design and delivery time, it has a competitive advantage in price and economy.
The weight of the cast steel can vary widely. The weight small can be only a few dozen of the molten mold precision castings, while the weight of large steel castings can reach several tons, tens of tons and even hundreds of tons.
What is the difference between steel casting and forging steel?
The anisotropy of forging steel components is not significant, which is better than forging steel. Research shows that the rolling steel longitudinal mechanical properties usually slightly higher than the grade of steel, lateral performance is lower than steel, its average performance is essentially the same good quality steel roughly the same. Some high technology products, in the design process of the parts often have to consider the material in the three axes direction performance, the above-mentioned advantages of the cast steel parts deserve to be regarded enough.
Steel casting parts, regardless of their weight and volume, are easy to be designed according to the design of the parts with reasonable appearance and inner wheel porch, high rigidity, complex shape and no significant stress concentration. When single or small batch production, usable wood appearance (appearance and stamen box) or polystyrene gasification appearance, production preparation cycle is very short; In mass production, plastic or metal can be used, and proper molding process can be used to make the casting conform to the required size and surface quality. These characteristics are difficult to achieve in forging.
What are the casting characteristics of cast steel parts?
The casting characteristics of cast steel parts are: the mechanical properties of steel castings are higher than that of cast iron, but their casting performance is worse than that of cast iron. Due to the high melting point of cast steel, the liquid of molten steel is easy to oxidize, the liquid of molten steel is poor and the shrinkage is large, the shrinkage rate of the steel is 10 ~ 14%, and the line shrinkage is 1.8 ~ 2.5%. In order to prevent defects such as insufficiency, cold isolation, shrinkage and shrinkage, crack and viscous sand, it is necessary to adopt a more complex process than cast iron:
1. Due to the poor liquidity of the steel liquid, the wall thickness of the cast steel parts cannot be less than 8mm to prevent the casting of steel parts from being cold and water deficient. The structure of the pouring system is simple and the section size is larger than that of cast iron. Dry cast or hot cast; Properly increasing pouring temperature, average of 1520 ° ~ 1600 ℃, because of the high pouring temperature, liquid steel superheat, keep long liquid, liquid can be improved. But the water temperature is too high, can cause the defect such as grain size, heat crack, stoma and viscous sand. So generally small, thin wall and complex shape casting, the pouring temperature is about steel melting point temperature of + 150 ℃; Large, thick wall castings pouring temperature about 100 ℃ higher than the melting point.
2, due to shrinkage of steel more than iron, to prevent the casting shrinkage cavity, shrinkage porosity defect, adopts the riser and mostly on the casting process, cold iron and subsidies and other measures, in order to realize the solidification sequence. In addition, in order to prevent the steel shrinkage cavity, shrinkage, porosity and crack defects, should make its uniform thickness, avoid sharp corners and rectangular structure, sawdust are added into the mould with sand, add coke to the core, and the empty heart core and sand core and so on to improve the sand mold or core of breathable and back down