Work

Effects of Shielding and Drainage Gas Flow Rates on Weld Quality, Microstructure and Mechanical Properties of 304NG Stainless Steel in Local Dry Underwater Laser Welding

Year: 2026

Type: article

Abstract: The quality of underwater laser welds is strongly dependent on the flow rates of the shielding and drainage gases. This study investigated the effect of argon and drainage gas flow rates on the formation, microstructure and mechanical properties of 304NG stainless steel using local dry underwater laser welding. At a water depth of 100 mm, with a laser power of 3.0 kW and a welding speed of 8 mm/s, the optimal conditions within the tested range were a shielding gas flow rate of 30 L/min and a drainage gas flow rate of 80 L/min. These conditions produced a continuous weld bead with an attractive surface and yielded the highest average maximum tensile load of 4.31 kN. Metallographic observations revealed that the weld metal primarily consisted of austenite alongside skeletal and lamellar ferrite, while the hardness along the weld depth remained relatively consistent at around 180 HV. These results demonstrate that matching the flow rates of the shielding and drainage gases properly is essential for stabilising the local dry cavity and improving weld quality and joint performance.

Source: Metals

DOI: 10.3390/met16040423

Authors: Shuyue Luo, Yue Yang, Jianwei Dong, Yang Yang, Zhen Luo

Institutions: Tianjin University, Shanxi University

Language: English

Topic: Welding Techniques and Residual Stresses

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,137

Funder: National Natural Science Foundation of China