Improved 42 CrMo steel and method for machining knuckles through improved 42 CrMo steel

Abstract

The invention relates to the technical field of knuckle machining, in particular to improved 42 CrMo steel and a method for machining knuckles through the improved 42 CrMo steel. The improved 42 CrMo steel comprises chemical components of, by mass, 0.37% to 0.43% of C, 0.01% to 0.030% of S, 0.15% to 0.35% of Si, 0.6% to 0.9% of Mn, 0.95% to 1.2% of Cr, 0.16% to 0.25% of Mo and the balance Fe. The quenching temperature during machining of the knuckles is 830-840 DEG C. According to the improved 42 CrMo steel and the method for machining the knuckles through the improved 42 CrMo steel, by the restriction of dual factors of the components and the hardenability of the steel, the quality stability of the steel is greatly improved; by adjustment of the range of the components of nonmetallic elements and high-hardenability elements in the steel, the hardenability fluctuation of the round steel is reduced, and the core hardenability of the round steel is improved at the same time; the quality of thermal treatment after forging of workpieces is guaranteed, and the produced knuckles have better mechanical performance; the stability of the tempering metallographic structure is improved, the number of the workpieces with quenching cracks caused by the hardenability fluctuation of the steel is reduced, and the rejection rate is lowered; the failure rate of a quenching furnace is reduced as the quenching temperature is more stable.

Description

technical field [0001] The invention relates to the technical field of steering knuckle processing, in particular to an improved 42CrMo steel and a method for processing steering knuckles using the steel. Background technique [0002] The steering knuckle is one of the important parts in the steering axle of the car, which can make the car run stably and transmit the driving direction sensitively. When the car is running, it bears variable impact loads, so the mechanical performance of the steering knuckle is very high. The domestic mechanical performance requirements for steering knuckles are: tensile strength 880-1030N / mm, heat treatment hardness HB269-314. European requirements for the mechanical properties of steering knuckles are higher than domestic standards, specifically: yield strength > 825N / mm, tensile strength 1030-1180N / mm, heat treatment hardness HB304-350, impact energy (Aku) > 40J, elongation > 11%, reduction of area > 42%, grain size ≥ 5 grades...

AI Technical Summary

Problems solved by technology

Among them, the Cr and Mo components can significantly improve the hardenability and strength of the steel, but it may also cause a large number of quenching cracks, resulting in a large number of scrapped products, and will greatly increase the cost.

According to the test, when the content of C, S and other non-metallic elements and some strong hardenability elements such as Cr, Mo, Mn are high, the hardenability value J30 will tend to the upper limit, the product is easy to crack, the crack is long and deep, The cracked workpiece is scrapped, so when 42CrMo steel is used to process the steering knuckle, the scrap rate is high

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