Effect of process parameters on track geometry, microstructural evolution on 316L stainless steel multi-layer clads

In the present work, the effect of process parameters such as laser power, scan speed and powder flow rate on the geometry and surface waviness of the bead during Laser Metal Deposition (LMD) was determined. A gas atomized powder of 316L stainless steel were employed, which were deposited on a stainless steel substrate at a rate of 2 kg/h. The experimental results indicated that the bead height, bead width and its wetting angle with respect to the substrate decreases with increasing scan speed and decreasing laser power. Here the scan speed and laser power exhibited contrasting effect on the shape and morphology of the bead. After analyzing the effects of process parameters, various deposition strategies were explored to fabricate a solid cylindrical sample followed by microstructural analysis and hardness measurements. The analysis of microstructures revealed the presence of solidification tracks, and columnar and homogeneous cellular dendritic grains, which are common features of additively manufactured alloys. Moreover, the optimized parameters of LMD were able to manufacture a 316L stainless steel with microhardness similar to that of as-cast and wrought samples of the same alloy.