Effect of Laser Remelting of Weld Toe on Fatigue Strength of Aluminum Alloy A5083P-O Welded Joint

Abstract

The effect of laser remelting of weld toe on fatigue strength of A5083P-O aluminum alloy welded joint (plate thickness: 6 mm) was investigated using 2 kW CO₂ laser facility with an intersecting and rotating optical system.
The following experimental results were obtained;
1) The fatigue strength of welded joint was increased by laser remelting of the weld toe, when the travel speed was 500 and 800 mm/min at laser power of 2 kW.
2) The main reasons for the improvement in fatigue strength were the increases in radius of weld toe and hardness of remelted zone by laser remelting.
3) The influence of travel speed on microcracks of remelted zone was significant, and crack sensitivity of remelted zone increased with decrease of travel speed less than 500 mm/min.
4) These cracks were considered to be hot cracking due to significant segregation of magnesium on grain boundary.