中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 34 No. 3 March 2024 |
（1. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China;
2. Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Tsinghua University, Beijing 100084, China;
3. School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China;
4. State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China;
5. Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095, China;
6. Beijing Higher Institution Engineering Research Center of Energy Engineering Advanced Joining Technology, Beijing Institute of Petrochemical Technology, Beijing 102617, China）
Abstract:Laser welding of the new nickel-based alloy K439B applied for engine turbine was carried out. The effects of post-welding heat treatment (PWHT) on the microstructure and mechanical properties of the joints were investigated. Semi-quantitative statistical results show that after PWHT, γ'''' phases in the whole joint grow up, and the radii of the primary and secondary γ'''' phases are about 25 and 150 nm, respectively. The results of mechanical properties show that PWHT improves the microhardness in the weld by about HV 100, and the critical resolved shear stress provided by γ'''' phases increases from 4.8 to 92 MPa. The tensile strength and yield strength of the heat-treated joint are comparable to those of the base metal. The presence of a large amount of carbides is the reason for the preferential fracture of the base metal during the tensile process.
Key words: nickel-based superalloy; laser welding; γ'' phases; carbides; microstructure; mechanical properties
