A combined full-field imaging and metallography approach to assess the local properties of gas tungsten arc welded copper-stainless steel joints

The local material properties of gas tungsten arc welded (GTAW) C21000 grade copper alloy (Cu) to AISI 304 grade stainless steel (SS) joints using (ErNiCu-7) filler material are studied using a range of material characterization techniques. Electron Back Scattered Diffraction (EBSD) studies across the weld confirmed the relationships existing between the solidification modes (dendritic, planar) and their corresponding grain morphology in a high resolution. The SEM-Backscattered Electron Mode (BSE) integrated with Energy Dispersive Spectroscopy (EDS) analysis evidenced the local heterogeneous compositions across the dissimilar weld. The global and local mechanical performance of the weld joints are assessed using a conventional uniaxial tensile tests and full-field 2D-digital image correlation (DIC) respectively. The local material behaviour of the weld joint is in-line with the compositional and microstructural gradients. The weld joint has achieved the ultimate tensile strength (UTS) of 258 +/- 14 MPa, which is very close to the strength of the Cu base metal (BM) and all the joints were fractured in the Cu-HAZ. Microhardness distributions measured using a spatially positioned indents found that the weld fusion zone (129.28 +/- 19.22 HV) has higher hardness in compared to the Cu-BM (80.51 +/- 2.58 HV). (C) 2018 Politechnika Wroclawska. Published by Elsevier B.V. All rights reserved.