1. AVIC Xi’an Aircraft Industry Group Company Ltd., Xi’an 710089, China;
2. State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
Abstract：This paper compared the fatigue crack growth rate of the base metal (BM), heat affect zone (HAZ) and weld metal (WM) of the ultra-high strength steel electron beam welded joint of 26mm thick 30CrMnSiNi2A. The experimental results showed that the fatigue crack growth resistance of the BM was the best; HAZ was relatively weak; WM was closed to that of the BM. The fractured morphologies of BM, HAZ and WM fatigue samples were observed. It was found that multi-source crack initiation was found in each region of the joint, fatigue striations were found in the stable and fast crack propagation area, and a large number of dimples were found in fractured zone of the three regions of the joint, presented ductile fracture characteristics. The microstructure characteristics of the three regions of the joint were observed by optical microscope and scanning electron microscope. It was found that the differences between the microstructure of each region of the joint were slightly, and all of them were tempered martensite.
2022, 
