Nodular iron casting for heavy axle main speed reducer shell and preparation process of nodular iron casting

Abstract

The invention relates to a nodular iron casting for a heavy axle main speed reducer shell. The nodular iron casting is prepared from following elementary components in percent by mass: 3.40-4.0% of C,1.90-2.30% of Si, 0.30-0.50% of Mn, 0.30-0.40% of Cu, 0.20-0.36% of Mo, 0.02-0.04% of Sn, 0.01-0.020% of Sb, smaller than or equal to 0.04% of P, smaller than or equal to 0.035% of S, 0.038-0.06% ofMg, 0.02-0.04% of RE and the balance Fe and inevitable impurities. The nodular iron casting for the heavy axle main speed reducer shell and a preparation method of the nodular iron casting are provided aiming at the problems that a speed reducer shell of a heavy axle is large in force bearing, complex in force bearing and high in required strength. The nodular iron casting for the heavy axle mainspeed reducer shell is low in alloy, high in strength and low in cost. According to the method, mainly, furnace charges of waste steel, nodular cast iron slag and carburant are matched, a small amountof copper, molybdenum, tin and antimony alloy is added, the interval degree of a thermal treatment casting is controlled, and in cooperation with thermal treatment processes of spraying and air-cooling, a metallographic structure is obtained, wherein the metallographic structure comprises larger than or equal to 95% of carbide-free pearlite and granular ferrite. The casting has the beneficial effects of being high in tensile strength, not high in hardness, high in toughness, good in machinability and the like, and the excellent mechanical performance and the low production cost of the nodulariron casting for the axle main speed reducer shell are achieved.

Description

technical field [0001] The invention relates to the technical field of cast iron metallurgy, in particular to a ductile iron casting for a heavy-duty axle main reducer housing and a preparation process thereof. Background technique [0002] Heavy-duty engineering vehicles play an important role in national economic construction and national defense transportation. There are large differences between the north and the south of my country, the road conditions are complex and changeable, and the workplace environment is changeable and harsh. Heavy-duty vehicles have heavy workloads, and the main transmission rear axle and main reduction housing will be subject to dynamic, static and asymmetrical cycles of up, down, left and right loads, and the force is very complex and changeable. In order to better adapt to the variability of the workplace, the main reduction housing is required to have the characteristics of light weight and small size, and ensure high mechanical strength a...

AI Technical Summary

Problems solved by technology

Usually, high-strength ductile iron castings need to add a variety of high-content alloying elements, which is prone to segregation of alloying elements, and the production cost of castings is high.

After the heat treatment of the castings, due to the different heat dissipation conditions of each casting and the difference in the wall thickness of the casting itself, the cooling rate is different between the castings and between the different wall thicknesses of the same casting, and finally causes heat treatment. The consistency of mechanical properties is poor, and the mechanical properties of castings after heat treatment are lower than those of test rods (specimen)

After the above two heat treatments, the hardness of the castings is relatively high, and there are technical problems that are not easy to process