TIG Welding Methods of Repairing Steel Components with Stainless Steel Coatings

Structural steel components tend to wear when exposed to corrosive and cyclic loading environments. These components can be repaired by welding on failure. This study studied the weld parameters and weld quality (porosity, depth of penetration, and coating thickness), hardness, corrosion, and wear resistance during repair welding. Mild steel samples were weld coated by varying alternating (AC) and direct (DC) currents: 40 A, 50 A, 55 A, 60 A, 65 A, and 70 A. The base material used was AISI 1045 steel, and Castolin 6825 was used as the welding electrode. The results showed that three wear mechanisms were dominant: abrasion, adhesion, and delamination. The porosity in the coated samples increased with increasing currents for both AC and DC. The welding current and current type influenced the coating thickness and penetration depth. When dipped in warm NaCl solution, the corrosion mechanism experienced by both sets of coated samples was pitting corrosion. In both cases (alternating and direct currents), the hardness values increased towards the coating surface from the substrate.