Abstract: A front lifting lug made of 30CrMnSiA alloy was broken and failed, whose fracture characteristics were analyzed and the hardness test was carried out. The results show that the fracture of the lifting lug is hydrogen embrittlement fracture and there is a phenomenon of excessive hardness. By combining the lug heat treatment and surface treatment process, it shows that incomplete hydrogen removal during surface treatment is the main cause of hydrogen embrittlement. Excessive hardness not only increases hydrogen embrittlement sensitivity, but also misleads the dehydrogenation process, so it is necessary for the lifting lugs to avoid excessive hardness. At the same time, the failure event reflects the lack of supplier quality control, and it is necessary to strengthen control and audit efforts in special processes and secondary outsourcing.

Key words: lifting lug, 30CrMnSiA alloy, hydrogen embrittlement fracture, excessive hardness, supplier quality control