Microstructure and high temperature fracture toughness of NG-TIG welded Inconel 617B superalloy

Xiaogang Li¹，Kejian Li¹，Shanlin Li¹，Yao Wu²，Zhipeng Cai^1,3,4，Jiluan Pan¹

1. Department of Mechanical Engineering, Tsinghua University2. Tsinghua University Research Institute for Advanced Equipment3. State Key Laboratory of Tribology, Tsinghua University4. Collaborative Innovation Center of Advanced Nuclear Energy Technology, Tsinghua University

摘 要：In the present study, the microstructure, fracture toughness, and fracture behavior of Inconel 617 B narrow gap tungsten inert gas（NG-TIG） welded joint were investigated systematically at the designed service temperature of 700℃. Fracture toughness(J_0.2) of base metal（BM） and heat affected zone（HAZ） was higher than that of weld metal（WM）. In HAZ and BM, strain mainly loc alised at grain boundaries with large misorientation and there were lots of coincidence site lattice（CSL）∑3 boundaries related to twins inside grains, which led to the much higher fracture toughness of BM and HAZ than WM. The high numbers of twins as well as the less serious strain localization at grain boundaries resulted in the most outstanding fracture toughness of BM.

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