MAN8L32/40柴油机进气阀出现了批量化失效,遂对失效进气阀进行了金相、断口、硬度以及应力分析。结果表明,在进气阀的生产过程中由于焊接工艺不合理,造成其组织应力、热应力过大,并在后续去应力环节未能彻底消减残余应力,导致其阀面产生裂纹。裂纹由外向内扩展,并最终导致进气阀失效。 MAN8L32 / 40 diesel intake valve appeared batch failure, then failed intake valve metallography, fracture, hardness and stress analysis. The results show that due to the unreasonable welding process in the process of intake valve, the stress and thermal stress of the valve are too high, and the residual stress can not be completely eliminated in the subsequent stress-relieving process, resulting in the crack on the valve surface. The crack expands from the outside to the inside and eventually leads to the failure of the intake valve.