Impact toughness variations of multi-pass, multi-layer CrMoV submerged arc welding weld metal
TIAN Hongwei1, LU Li2, ZHAO Chongyang1, SHI Xiangwen1, LI Kejian3
1. Jianbi Power Plant, National Energy Group, Zhenjiang 212006, China; 2. Suzhou Nuclear Power Research Institute, Suzhou 215004, China; 3. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
Abstract：After post-welding heat treatment, the impact toughness of CrMoV weld metal from multi-pass, multi-layer submerged arc welding fluctuated greatly at room temperature. The microstructures and crack propagation paths of various samples were characterized using optical and scanning electron microscopes with the fracture surface morphology observed using a scanning electron microscope. In addition, the carbides in the matrix were analyzed using an Auger electron spectroscope. The results show that the reheated coarse-grained zone of the weld metal is the weakest microstructure component for the impact toughness and that the necklace-like distributed Fe3C carbides and nonmetallic inclusions can lead to crack initiation. The location of the V-shaped notch in the weld metal is the key factor determining the impact absorbed energy. A larger distance between the V-shaped notch and the reheated coarse-grained zone in the direction along the crack propagation path increases the weld metal impact toughness.
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2021, Vol. 61 
