Diode Laser Weld Toe Re-melting as a Means of Fatigue Strength Improvement in High Strength Steels

Re-melting of weld toes to improve the surface profile and thus reduce stress concentrations is a known fatigue improvement technique. In the study reported here, a novel approach was taken, using a diode laser as heat source. Different diode laser treatment conditions were tested, using the diode laser power, spot size and shape, and the travel speed as main parameters. Fillet welded samples in S690QL and S960QL in 10 mm thickness were treated and fatigue tested with constant amplitude loading. In response to those initial results, further samples were welded and treated and variable amplitude fatigue testing was undertaken.