Abstract
Ni-based filler metal and Ni-Cu-based filler metal were used to obtain copper/stainless steel (Cu/SS) joints through wire-feeding laser welding. Along the SS/weld interface, there exist different grain sizes (from coarse columnar grains to fine equiaxed grains). The heat affected zone (HAZ) on the copper side consisted of two areas with different grain sizes and the size of the grain in the Cu-HAZ of the Ni-Cu-based filled joint was much smaller than that of the Ni-based filled joint. Our results showed that grain refinement at the copper/weld (Cu/weld) interface of the Ni-Cu-based filled joint was observed through high-resolution electron backscattered diffraction (EBSD). There was a hardness elevation at the Cu/weld interface of the Ni-Cu-based filled joint due to the grain refinement on the weld of the copper side. The maximum tensile strength of the Ni-Cu-based filled joint was obtained and reached 91.2% of the tensile strength of the copper base metal (Cu-BM). Joints in this study were observed to fracture in a ductile mode. Furthermore, the Ni-Cu-based filled joint exhibited a higher plastic deformation, which was primarily caused by the large deformation of the weld zone and the large deformation of the Cu-BM due to the high plasticity of the weld, which alleviated the stress concentration, as indicated by 2D-digital image correlation (DIC) test results.
Highlights
Because of the excellent thermal conductivity and ductility of copper-based alloys, and the excellent resistance to corrosion of austenitic stainless steel, both have been widely used in the power generation industry
Meng [4] showed that defect-free joints could be obtained when the laser offset was 0.5~1 mm on the copper side; joints under the optical laser offset all fractured at the copper side and the achieved tensile strength was 90% of the base copper metal, and when the laser offset exceeded 1 mm, coarse copper columnar grains were formed in the weld, which deteriorated the mechanical properties of the joints
Kuryntsev [6] achieved a defect-free copper/steel fiber laser welded joint by focusing the laser point on the steel side; the stainless steel was melted by the laser while the copper was melted by the conducted heat, and the Cu-heat affected zone (HAZ) consisted of two regions with different grain sizes
Summary
Because of the excellent thermal conductivity and ductility of copper-based alloys, and the excellent resistance to corrosion of austenitic stainless steel, both have been widely used in the power generation industry. Kuryntsev [6] achieved a defect-free copper/steel fiber laser welded joint by focusing the laser point on the steel side; the stainless steel was melted by the laser while the copper was melted by the conducted heat, and the Cu-HAZ consisted of two regions with different grain sizes. Research on the microstructure of wire-fed laser welded joints and the correlation with mechanical properties was not in-depth.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
