Study On Nitriding Behavior And Microstructure Of SLM High Nitrogen Stainless Steel

As an important branch of additive manufacturing technology,selective laser melting technology is valued by many scholars at home and abroad,and is regarded as one of the popular process technologies in the current manufacturing industry.High nitrogen stainless steel is widely used in production and life because of its excellent comprehensive properties.The basic forming experiments of nitrogen-containing stainless steel powder were carried out by Conventional Selective Laser Melting(CSLM)and High-Pressure Selective Laser Melting(HPSLM);The effects of process parameters on single pass molten pool morphology,single pass and block forming quality,microstructure,relative density and micro surface hardness were analyzed.The results show that there is an appearance of nitrogen escape in the conventional SLM forming process,and the SLM process can inhibit the degree of nitrogen escape.The nitrogen loss rate is the lowest at low energy density of 45.45j/mm~3,which is 13.8%,and the nitrogen loss rate is the highest at high energy density of 680j/mm~3,which is54.7%;The nitriding behavior exists in the process of high-pressure SLM forming.When the cavity pressure is 0.1MPa,the nitriding amount is 0.064wt%,and when the cavity pressure is 1.5MPa,the nitriding amount is 0.73wt%.The microstructure of the superimposed surface of CSLM sample is mainly columnar band,lath structure and staggered needle structure composed of fine columnar and cellular crystals.Considering the Nitriding Behavior in the conventional selective laser melting process,under the conditions of scanning interval of 0.11mm,rotation angle of 67°and scanning layer thickness of 0.02mm,high nitrogen stainless steel with less nitrogen loss and excellent forming quality can be prepared with 100W laser power,500mm/s scanning speed,200W laser power and 1000mm/s scanning speed respectively.Figure 49;Table 6;Reference 96...