Formation Quality Optimization and Corrosion Performance of Inconel 625 Weld Overlay Using Hot Wire Pulsed TIG

Based on the central composite rotatable design (CCD), clad beads of Inconel 625 were deposited on the surface of AISI 4130 plates using hot wire pulsed TIG (tungsten inert gas arc welding) technique. The response surface methodology (RSM) was used to establish models between process parameters and geometrical characteristics of the clad beads. Then, multiple-track two-layer weld overlay was deposited using the optimized process parameters. The microstructure of the weld overlay is primarily composed of columnar dendrites, and there are also a few planar crystals and cellular dendrites near the fusion zone. Meanwhile, equiaxed grains and steering dendrites are mainly distributed in the upper portion of the weld overlay. Potentiodynamic polarization tests were used to evaluate the corrosion resistance of the weld overlay and the substrate. The results show that adding clad layers can enhance the corrosion resistance, which degrades with the increase in Fe dilution. Moreover, the corrosion resistance of the second layer surface is close to that of wrought Inconel 625.