Effect of Shielding Gas Composition on Bead Shape and Fatigue Life with Low-Transformation-Temperature Welding Material

In this study, 1-pass bead-on-plate welding was performed using low-transformation-temperature welding materials under constant voltage and current condition with various shielding gas compositions to investigate stress concentration at the wel d toe. Tensile fatigue tests were also conducted using specimens with the weld bead to examine the effect of shielding gas composition on the fatigue life. The stress intensity factor at the weld toe was lowest when Ar shielding gas was used, extending the fatigue life at the stress amplitude of 140 MPa by approximately 1.7 times, compared with CO2 containing shielding gas. Controlling the weld toe shape require managing the bead width and excess volume. Under constant voltage and current condition, reducing stress intensity factor at the weld toe can be achieved by increasing toe radius and reducing reinforcement contact angle relative to the bead width.