40CrNiMo小轴热处理后开裂失效分析

Failure Analysis on Post-Heat Treatment Crack of 40Cr Ni Mo Small Shaft

对40Cr Ni Mo小轴热处理后出现中心裂纹的化学成分、硬度、显微组织和断口形貌等进行了检测与分析。结果表明,热处理后小轴开裂主要是由于炼钢时,冒口端切除部分太少、零件中心成分偏析严重,以及碳化物网状分布等原材料缺陷造成。

The test and analysis have been carried out for the chemical composition, hardness microscopic structure, fracture section appearance, etc of the center cracks occurred after post-heat treatment of 40CrNiMo small shaft. The result shows that the crack of small shaft after heat treatment are mainly caused by the defects of raw material, such as too less removal at cutting end, serious composition deflection at part center and reticulose distribution of carbide, etc.