Abstract: Welding is an important means of connecting steel structures, and the fatigue performance of welded joints is related to the safety of steel structures. In order to improve the fatigue performance of welded joints in steel structures, this study proposes to use laser remelting to treat welded joints. For this purpose, this study conducted high cycle fatigue tests on the welded joints and laser remelting treated joints of Q355 steel plate butt welding. Fatigue fracture analysis was conducted using scanning electron microscopy, and the stress life (S-N) fatigue curves of the welded joints and laser remelting welded joints were fitted based on the test results, and compared with the standard fatigue formula. The experimental results show that laser remelting treatment can change the location of fatigue fracture in welded joints and significantly improve the fatigue life of welded joints; The fatigue performance design curves provided by the American Steel Structure Code ANSI/AISC360-22, European Code EN 1993-1-9:2005, and Recommended Method for Offshore Steel Structure Design DNV-RP-C203 tend to be conservative for welded joints treated with laser remelting.

Key words: welding joints, laser remelting, high cycle fatigue, fatigue strength, fatigue fracture surface