Abstract:
Objective In the pickling production process of 430 hot-rolled stainless steel, welded joints undergo repeated bending on the production line, posing risks of cracking. The aim of this study is to investigate weldability of 430 hot-rolled stainless steel, address fracture susceptibility of welded joints during manufacturing, and improve bending fatigue life of welded joints.
Methods This study innovatively applied XY-ER80QNH high-strength steel welding wire to 430 hot-rolled stainless steel welding. Narrow-gap MAG welding tests without opening groove were conducted using this high-strength steel welding wire with multiple processes. Microstructure and microhardness of welded joints were analyzed. To simulate field conditions, repeated bending tests were employed to evaluate joint bending fatigue performance.
Results Results indicate that compared to traditional ER309L welding wire, welded joints with high-strength steel welding wire demonstrated significantly enhanced fatigue life, with two-pass welding showing further improvement over single-pass welding. Weld zone with high-strength steel welding wire primarily consists of martensite and acicular ferrite, effectively improving joint strength and toughness. Carbides dispersed in heat-affected zone and weld metal with high-strength steel welding wire contribute to dispersion strengthening. Two-pass welding process with lower heat input results in finer grains in heat-affected zone, cover pass decomposes martensite formed in root pass, and two passes create hourglass-shaped welds that reduce stress concentration at fusion lines during face and root bends, thereby enhancing bending fatigue life. Post-weld heat treatment further improves bending fatigue performance. High-strength steel welding wire exhibits superior defect tolerance capability, with weld reinforcement showing no significant impact on fatigue life.
Conclusion Experimental results demonstrate that compared to ER309L stainless steel welding wire, welded joints with high-strength steel welding wire exhibit remarkable advantages in application, demonstrating stable bending fatigue life and excellent bending fatigue performance.