Study On Forming Process And Mechanical Properties Of 316L Powders By Selective Laser Melting

Selective laser melting (SLM) process can directly form the complex metal parts, and has become the most promising technology in the rapid prototyping technology. However, the development of SLM technology is still short in China, the basic research based on this technology is still relatively small. Therefore, in order to improve the quality of SLM forming parts, the density and mechanical properties of forming samples were systematically studied.The specific contents of the study are:(1) Study on the forming law of single channel. The surface quality of single channel sintering was studied by using different line energy input density. The results show that the surface quality can be divided into four regions: the melting zone, the partial melting zone, the full melting zone and the over melting zone.(2) Optimization of process parameters. The experimental parameters include rotation angle (?), powder thickness (h ), laser power (P), scanning speed ( v) and scanning interval(s). The optimized results were as follows: ?=600, h=0.04 mm, P=310W, v=960 mm/s,s=0.13 mm, while the density and mechanical properties of the samples are the best.(3) Analysis on micro structure and fracture morphology of the samples. The surface micro structure of the SLM shaped parts was observed, and the microstructure was fine and uniform, and the dimple size was uniform and fine. Combining all of the experimental results,the input energy density ( ?= P/(vsh) ) can be used as a unified parameter to study the effects of the process parameters on the density and mechanical properties of the samples,which has an optimal value to ensure the best density and mechanical properties of the samples, and whether it is lower or higher than the value, the density, tensile strength and yield strength of the samples decreased, the elongation rate can be slightly increased.(4) Study on metallurgical defects in SLM forming parts. The metallurgical defects in the SLM forming parts reduce the density and mechanical properties of the parts. The forms of metallurgical defects are pores, cracks, oxide inclusions and residual stresses. The optimization of the process parameters can improve the metallurgical defects in the forming parts.In summary, the results of this study provide a theoretical basis for the further study of the density and mechanical properties of SLM parts.