Chemical Behaviour of Copper in the Application of Unconstrained Cr-Ni-Al-Cu Metal Powders in Submerged Arc Welding: Gas Phase Thermodynamics and 3D Slag SEM Evidence

Unconstrained metal powders of Cu, Cr, Ni and Al were applied to submerged arc welding (SAW) clarify the chemical behaviour copper in this modified SAW process. Aluminium is avoided because it easily oxidised. Excessive aluminium oxides form slag or inclusions weld will lead poor materials properties. an effective deoxidiser can be used prevent Cr loss by preventing oxidation these metals. The results show that carbon steel was alloyed 5.3% Ni, 3.6% 5.2% Cu at 80% yield, 81% 54% yield 79% yield. BSE (backscattered electron) images three-dimensional (3D) post-weld sample 3D structures within dome. contain features vapour formation recondensation. In addition, nano-strands appear confirm vaporisation recondensation fluorides. powder added vaporise as metallic incorporate Al-Si-Mg-Ca-Mn-Fe-Cu-Na-Cr-Ni fluoride. Copper, combination with aluminium, has a stabiliser effect due its initial alloy melt low liquidus temperature, thus decreasing temperature required high-melting-point metals such into pool. Although have similar pressures specific temperatures, appears does not substitute for gas phase. Gas-slag-alloy thermochemical equilibrium calculations partial oxygen pressure lowering very little copper-fluoride species expected form. quantity calculated gas-slag-alloy much higher than measured welding. This may vaporised which accounted calculation set cavity well surface-active elements sulphur limiting reaction copper.