BJ130汽车后桥半轴套管,如图1所示,材料为45钢。要求淬火硬度≥HRC50,调质硬度为HRC25～32。原来采用的淬火工艺为850℃×1h加热,水冷到室温,在钢材化学成分正常时,合格率为97%,但当钢材中含B为0.001%,含W为0.02～0.03%,含Ma≥0.75%时,采用上述工艺淬火,淬裂现象时有发生,合格率仅为68%。淬裂部位见图2。为了减少半轴套管的淬火裂纹提高热处理件的合格率,我们对半轴套管材 BJ130 automobile axle axle sleeve, shown in Figure 1, the material is 45 steel. Requires quenching hardness ≥ HRC50, quenching hardness HRC25 ~ 32. The original quenching process was 850 ℃ × 1h heating, water cooled to room temperature, the normal chemical composition of the steel, the pass rate of 97%, but when the steel containing 0.001% of B, containing 0.02 to 0.03% W containing Ma ≥ 0.75%, the use of the above process quenching, quenching phenomenon occurs from time to time, the passing rate of only 68%. Hardened crack site shown in Figure 2. In order to reduce the quench crack half-shaft casing to improve the pass rate of heat-treated parts, we have a half-shaft casing