Analysis and control of welding characteristics in laser self-fusion and wire-filling welding of 304 stainless steel at different workpieces tilting angles

An experiment was conducted using stainless steel as the filler metal to investigate the influence of workpiece angle, welding torch angle, and wire feeding direction on weld formation in laser welding and filler wire welding. The results indicate that when the workpiece angle is 40°, the molten height and width are minimized, while the molten depth is maximized, resulting in the best welding quality and hardness. In laser filler wire welding, when the workpiece angle is 30°, the weld formation quality is optimal, with the molten width and depth achieving ideal values, and the molten height minimized. Based on the optimal weld formation at 30°, the molten width gradually increases, while both molten depth and height decrease with variations in the wire feeding directions. The upper microstructure is predominantly composed of columnar crystals, with their proportion significantly increasing as the wire feeding direction changes. The middle and bottom regions are more sensitive to changes in the wire feeding direction, with a significant increase in the proportion and orientation of columnar crystals, leading to a decrease in microstructure uniformity. The offset angle causes the weld surface to become irregular and the cross section to shrink. The sensitivity of the upper region to the offset angle is low, followed by the middle region, with the bottom region being the most sensitive. A small range of torch offset angles helps to optimize the uniformity of the weld microstructure, whereas a large offset angle tends to cause microstructure disorder and deterioration of the weld quality.