Abstract
Recently, the laser welding technology of carbon steel is being widely used compared with arc welding technology for its better welding characteristics. In the present study, the influence of welding conditions of both laser beam welding (LBW) and gas metal arc welding (GMAW) as a comparative study on the weld joint microstructures, hardness distribution and fatigue properties crosses the butt-welded joints of dual phase (DP) steel and mild steel are investigated. The results show that LBW produced narrow welds with complete penetration while GMAW produces wide fusion and heat affected zones. The microstructure of the fusion zone of laser welded DP steels contains mainly bainite, martensite, and a few amount of acicular ferrite phases. Hardness values of the heat-affected zone (HAZ) for dual-phase (DP) steels showing lower values for both LBW and GMAW processes due to the tempering action of the martensite phase. A narrow softening region was clearly observed in the HAZ welded for LBW compared with GMAW. In general, the fatigue life of the welded joints is improved by using laser welding technique.
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