【摘要】 某汽车用D38MSV5S非调质钢曲轴在行车过程中发生断裂，通过对失效曲轴的宏微观断口、化学成分、金相组织、显微硬度等检测分析。结果表明：曲轴基体组织粗大、A类夹杂物分布不均、材料偏析严重、裂纹源区条状硫化物较多等缺陷，导致曲轴早期疲劳断裂。通过改善锻造工艺、细化晶粒、控制硫化物形态以及优化改进曲轴的圆角滚压强化工艺，采用适当的滚压力和滚压圈数等参数，获得理想的残余压应力状态；优化滚压加工质量和加工效率，才能有效体现曲轴的轴颈感应淬火强化方式+圆角滚压复合强化效果，提高曲轴抗疲劳断裂能力，有效延长曲轴寿命。更多还原

【Abstract】 The D38MSV5S non quenched and tempered steel crankshaft of a certain automobile fractured during driving. The macroscopic and microscopic fracture surface,chemical composition,metallographic structure,microhardness,etc. of the failed crankshaft were detected and analyzed. The results indicate that the matrix structure of the crankshaft is coarse,the distribution of A-type inclusions is uneven,the material segregation is severe,and there are many strip like sulfides in the crack source area,which lead to early fatigue fracture of the crankshaft. By improving the forging process,refining grain size,controlling sulfide morphology,optimizing the fillet rolling strengthening process of the crankshaft and adopting appropriate rolling pressure and number of rolling cycles ideal residual compressive stress state is achieved;Optimizing the quality and efficiency of rolling processing is necessary to effectively reflect the composite strengthening effect of induction quenching and fillet rolling on the crankshaft neck,improve the fatigue fracture resistance of the crankshaft,and effectively extend its lifespan.更多还原