Microstructure and Mechanical Properties of Laser Welded Joints of DZ125L and IN718 Nickel Base Superalloys
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The microstructure and mechanical properties of the laser welded joint of DZ125L and IN718 nickel base superalloys were investigated. The results show that the fusion zone (FZ) mainly consists of fine dendrite structure with fine γ′, Laves phases and MC carbides inhomogeneously distributed. The high welding temperature induces the partial dissolution of γ′ in the heat-affected zone (HAZ) of DZ125L and liquation of grain boundaries in both of the HAZs. After post-weld heat treatment (PWHT), fine γ″ and γ′ phases precipitate in the FZ, IN718 HAZ and IN718 base metal (BM), and fine γ′ precipitate in the γ channel of the HAZ and BM of DZ125L. With tensile testing, the joints after PWHT show higher strengths than that of the weaker DZ125L alloy. Plastic deformation mainly concentrates in the weaker DZ125L and the joint finally fails in the DZ125L BM.
KeywordsLaser welding Nickel base superalloy Post-weld heat treatment Microhardness Tensile properties
This work was supported by the National Natural Science Foundation of China (51571052 and U1708253), the Science and Technology Major Project (2017-VI-0002), and the Fundamental Research Funds for the Central Universities (N160204004).
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