科研之友
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摘要
A conventional rolled (R) GH4169 sheet and a selective laser melting (SLM) additive-manufactured (3D) GH4169 sheet were welded to comparatively investigate the microstructure and mechanical properties of the three (R/3D, R/R, and 3D/3D) welded joints. Optical microscopy, scanning electron microscopy, and energy-dispersive spectrometry were used to characterize the microstructure of the butt joints; microhardness and tensile tests were also performed on the butt joints. The test results show that the microstructure of the fusion zone is mainly transformed from cell crystals to dendrites or columnar crystals and a large number of δ phases and laves phases are formed in the intergranular and intragranular regions. The grain size and precipitated phase size of the R/3D GH4169 joint, R/R GH4169 joint, and 3D/3D GH4169 joint decrease in sequence, the average microhardness of the fusion zone increases successively (250 HV, 261 HV, and 274 HV, respectively), and the tensile strength of the joints increases successively (768 MPa, 799 MPa, and 985 MPa, respectively). The fracture mode of the R/3D GH4169 and R/R GH4169 joints is mainly ductile fracture, whereas the fracture mode of the 3D/3D GH4169 joint is brittle fracture.
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