Heat treatment and Yb-fiber laser welding of a maraging steel

Abstract

Maraging steels are iron-nickel alloys having an unusual combination of high mechanical strength and high toughness. In this work, the effects of laser welding and postweld heat treatments have been analyzed. The fusion zone showed a cellular-dendritic morphology with a relatively low hardness (=450 HV) compared to the heat-affected zones (HAZs) and base material (=500 HV). The segregation in the fusion zone increases the tendency of austenite phase formation during aging. The solutionized and aged coupons presented the highest yield strength values (=1890 MPa). Homogenization treatment showed to be effective on eliminating the as-cast dendritic structure of the fusion zone, but decreased the yield strength to about 1350 MPa, showing that this treatment should be used carefully. The welded specimens presented tensile strength close to the unwelded specimens, demonstrating that the ytterbium- fiber laser welding of l8Ni-type maraging steels could be considered.