Fatigue behaviour of laser welds of high-strength low-alloy steels

Abstract

High-strength low-alloy (HSLA) steels are a group of low-carbon steels designed to provide better mechanical properties and sometimes better corrosion resistance than conventional carbon steels. The laserbeam welding of HSLA steels can improve the productivity, increase the process reliability and avoid deformation in several industrial fields, as structural components, pressure vessels and linepipes, and in shipbuilding and offshore construction. An exhaustive analysis of the mechanical behaviour of welded joints from different points of view must be carried out for these processes to be able to go ahead. The behaviour of the laser welded HSLA steel studied is good, with a fatigue limit under the present test conditions of 260 MPa. Cracks usually start in the fusion zone, near to the borderline between the fusion zone and the heat-affected zone, the cracks growing right into the base metal by the transcrystalline cracking process.