The effect of low-power laser on micro-forming of 316 stainless steel additive manufacturing part

316 stainless steel was fabricated with novel low-power pulsed laser-induced gas tungsten arc additive manufacturing (LGTA-AM). Compared with gas tungsten arc additive manufacturing (GTA-AM) process, the microstructure, phase composition and room temperature mechanical property were investigated. Compared with the micro-molding of walls fabricated by GTA-AM, the room temperature micro-structure of the two processes are composed of A and δ ferrite. The austenite grains show cell-like crystals → columnar crystals → dendrites → equiaxed crystals from bottom to top of 8-layer wall. The ferrite morphology of the GTA-AM specimens captured by SEM was strip-shaped, skeleton-shaped, sieve-shaped, and worm-shaped in order from bottom to top. The ferrite morphology of LGTA-AM specimens captured by SEM is strip-shaped, fine-mesh-shaped, reticulate-shaped, and fish-scaled in order from bottom to top. LGTA-AM can uniformly refine the micro-structure and accelerate the transformation rate from ferrite to austenite. The hardness value of the AM wall from the bottom to the top shows a trend of decreasing first and then increasing. The LGTA-AM process can improve the uniformity of the interlayer transition and reduce the anisotropy of the grains.