汽车前轴用40Cr钢锻件开裂失效分析

Cracking failure analysis of 40Cr steel forgings for automobile front axle

利用化学成分、显微组织以及硬度分析等方法,对汽车前轴用40Cr钢锻件的开裂原因进行了分析。结果表明:裂纹位于锻件的R角处,为淬火裂纹;锻件R角处的元素偏析造成淬透性显著高于周围其它位置,锻造过程中产生了表面缺陷,使得淬火时马氏体相变产生的体积内应力超过了材料的强度,造成了淬火裂纹的产生;通过增大R角半径、控制原材料的成分偏析以及调整锻造工艺等措施,能够减小汽车前轴用40Cr钢锻件热处理后淬火开裂的风险。

Cracking reason of 40 Cr steel forgings used for automobile front axle was analyzed by means of chemical composition, microstructure and hardness analysis. The results show that the crack is a quenching crack occurred at the R angle of the forgings. The elemental segregation at the R angle of the forgings results in significantly higher hardenability than that of other locations around. Surface defects are produced in the forging process, so that the volume stress generated by martensitic transformation during quenching exceeds the strength of the material, resulting in the generation of quenching cracks. By increasing the R angle radius, controlling the chemical segregation of raw materials and adjusting the forging process, the risk of quenching cracking of 40 Cr steel forgings for automobile front axle after heat treatment can be reduced.