Preparation and application of 316L stainless steel powder for selective laser melting process

As an important supplement to the traditional manufacturing industry, the selective laser melting (SLM) has been gradually applied to the fields of aerospace and automobile production. However, the product quality of SLM is closely related to the alloy powder characteristics. In this work, a two-dimensional axisymmetric mathematical model of gas atomization at unsteady state, which takes a secondary break-up and solidification model into consideration, is developed. The optimal nozzle structure of gas atomization includes a nozzle width of 0.6-1 mm and a nozzle angle of 30-32°. Thus, the yield of narrow and fine-sized (15-45 μm) 316L stainless steel powder, suitable for SLM process, greatly increases from 20% to 35%. In addition, the other performance of alloy powder is similar or even better than that of a special powder for additive manufacturing. Furthermore, the effect of SLM process parameters, including the laser power and scanning speed, on the melting channel width, microstructure and mechanical properties of SLM product is also investigated. In order to prevent the unmelted or spheroidized of 316L stainless steel powder, the laser power should be controlled at 350-400 W, and the scanning speed should be controlled at 1500-2000 mm/s.