Influence of forming atmosphere on the deposition characteristics of 2Cr13 stainless steel during laser solid forming

A series of single track clads and bulk samples were prepared by laser solid forming under atmospheres of air, argon and nitrogen. The forming atmosphere has little effect on the variation of the width and height of a single track clad with scanning velocity, laser power and feeding rate. Under air, the width and height of single track clads are the largest. Under argon, they are slightly larger than those under nitrogen when the laser energy density is high. For bulk samples prepared under air and nitrogen, both sidewalls of the cross-section tilt inward in the lower part; with an increase in the deposition height, the sidewalls tend to be oriented vertically. Under argon, the sidewalls maintain their severe inward tilts from the bottom to top of the bulk sample. Under air, the bulk sample is covered by oxide dross. Fine and dense metal beads are attached to the lower sidewalls under argon, but these beads are coarse and sparse under nitrogen. The effects of the forming atmosphere on the effective energy, effective mass and deformation of the molten pool during laser solid forming were analyzed. The influence of the atmosphere is attributed to the exothermic oxidation reaction under air, the more extensive plasma plume effect under argon and the larger deformation of the molten pool under air and nitrogen.