MICROSTRUCTURE EVALUATION OF DISSIMILAR LASER BEAM WELDS –MDN 250 AND 15CDV6 STEELS

Abstract

A novel dissimilar Laser Beam Weld of MDN 250 and 15CDV6 steels with adequate joint strength was successfully achieved using CO2 laser source. Electron probe microanalysis of the weld, weld microstructure, micro-hardness measurement across the weldment and transverse tensile properties of the weldment were evaluated. The fusion zone of the dissimilar welds exhibits an epitaxial grain growth. In dissimilar metal welds, HAZ (Heat Affected Zone) width is more on 15CDV6 steel side compared to MDN 250 steel side. An asymmetrical hardness profile across the dissimilar weld joint was observed, and HAZ region on 15CDV6 steel exhibited a high hardness. The tensile strength values of the welded specimens were close to that obtained for sheet specimens.

Keywords

• laser beam welding
• mdn 250 steel
• 15cdv6 steel
• mechanical properties
• microstructure