Study on Structure and Property of Ductile Iron Automobile Brake Pliers at Different Wall Thicknesses
Understanding the structure and property of different wall thickness of automobile brake clamp ductile iron casting is conducive to improving the product quality and stability.With the brake clamp of QT 500-7 and QT 550-6,the influence of casting wall thickness on ductile iron graphite,the structure of the matrix and the hardness was studied.The results show that the brake clamp from part A to C,as the wall thickness increases in turn,the graphite spherical rate change is not big,The number of graphite particles increases first and then decreases,the average diameter of graphite first decreases and then increases,the pearlite content and Brinell hardness first decreased and then increased,pearlite sheet spacing change trend with Si element micro content change trend close to consistent.The wall thickness of A is smaller than that of B,but due to the different temperature field distribution in the solidification process,the temperature field of A is higher than that of B,so the number of graphite particles in A is smaller and the average diameter of graphite is larger.Thickness site C and slower cooling site A are more abundant than pearlite in site B because of the influence of stable pearlite elements such as Mn segregation,and the slower the cooling rate,the worse the segregation.The difference in the structure and property of the different wall thickness of the casting is essentially the result of the combined influence of the cooling speed and the microzone composition.
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