Characteristics of CO₂ Laser welded 1000 ㎫ Grade TRIP Steel

Characteristics of CO₂ Laser welded 1000 ㎫ Grade TRIP Steel

  Characteristics of CO₂ laser welded 1000 ㎫ grade Transformation Induced Plasticity steel were investigated under varying welding power, welding speed and different shield gas. Decreasing welding power, increasing welding speed or using mixed gas (Ar+He) reduced the porosity in the weld metal. Weld metal (WM) and HAZ near the WM had maximum hardness. In tensile strength test of load perpendicular to the weld axis, the specimens had same tensile properties as that of raw material. For the load parallel with the weld axis, the specimens prepared with Ar had equal yield strength (YS) and tensile strength (TS) to that of raw material. But the elongation was lower than that of raw material. The specimens prepared with He had higher YS, TS and lower elongation compared with that of raw material. Welded material had lower formability than that of the raw material. The formability of specimens prepared with low welding power or Ar+He was improved compared with that of specimens prepared using high power or Ar.