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在生产45钢活塞杆时发现,经表面感应加热淬火的活塞杆在磨削加工时表面产生微裂纹。成分和组织分析表明,活塞杆所用钢材符合45钢化学成分要求,由于缺少必要的锻造和调质处理,其原始组织保留了大量的粗大网状铁素体,不满足后续表面强化对心部组织的要求。因活塞杆感应加热淬火操作不当,硬化层出现软带,使有效硬化层深度及表面硬度波动范围大大超过技术要求。活塞杆表面磨削不当又诱发拉应力,残存的铁素体被直接撕裂形成表面裂纹。
In the production of 45 steel piston rod found that the surface induction heating quenched piston rod surface micro-cracks in the grinding process. The composition and microstructure analysis show that the steel used in the piston rod meets the requirements of the chemical composition of 45 steel. Due to the lack of necessary forging and tempering treatment, its original structure retains a large amount of coarse meshed ferrite, which does not meet the requirements of subsequent surface strengthening on the heart tissue Request. Due to the improper operation of induction heating and quenching of the piston rod, a soft belt appears on the hardened layer, so that the effective hardened layer depth and the surface hardness fluctuation range greatly exceed the technical requirements. Piston rod surface grinding induced tensile stress again, the residual ferrite is directly torn surface cracks.