Interlocking effect on residual stress and distortion of Laser-Welded A304 steel plates

Laser welding is widely used in industries for the assembly of various products such as ships, automobiles, trains, and bridges. Residual stress and welding distortion often result in dimensional inaccuracies during assembly and increased construction costs. Therefore, predicting and reducing welding distortion is crucial for improving the quality of welded structures. This research focuses on the analysis of residual stress and distortion in two laser-welded A304 steel pieces. Standard and Interlocking welding methods were employed for the joints. Electron microscopy was used to examine the microstructure. Mechanical behavior was assessed through tensile testing, microhardness measurement, residual stress, and distortion analysis. Residual stress in different welding zones was measured using X-ray diffraction. The results indicated that the metal's microstructure in the weld is austenitic with skeletal ferrite in some areas. The microhardness of the standard weld metal increases by approximately 22% compared to the base metal, attributed to the formation of a skeletal ferrite phase in the weld metal while this value is 11% for the Interlocking one. The yield and tensile strength of the interlocking-welded sample increased by about 8% and 1.2%, respectively, compared to the standard-welded sample. Distortion results showed a 12.6% and 10.5% change in the angle for Standard welding and Interlocking welding compared to the baseline. Additionally, changes in height for Standard and Interlocking welding were approximately 5.2% and 28.9%, respectively, compared to the baseline.