Effect of Energy Density on Selective Laser Melting Quality of High Nitrogen Stainless Steel
Under the scanning layer thickness of 0.02 mm,scanning spacing of 0.11 mm,the selective laser melting tests of high nitrogen stainless steel was carried out at different laser power of 100-300 W and scanning speed of 200-1000 mm/s.And the effect of process parameters on the selective laser melting quality of the high nitrogen stainless steel was studied.The results show that under the low scanning speed of 200 mm/s,the relative density of the sample is inversely proportional to the laser power,and under the high laser power of 300 W,the relative density of the sample is proportional to the scanning speed.In the range of 45.45-681.82 J/mm3,the relative density increases first and then decreases with the increase of laser energy density.In the range of 136.36-443.18 J/mm3,the microhardness decreases with the increase of laser energy density.When the energy density is 136.36 J/mm3,the relative density of the sample is the best of 98.85%,and the microhardness is the highest of 409 HV0.3.There are no large-scale crack defects in the sample under various parameters.The internal defects are mainly unfused powder,micro pores,and balling particles.Under the laser power of 200 W,the number and type of internal defects in the sample increase with the decrease of scanning speed.Under the scanning speed of 1000 mm/s,the number and type of internal defects in the sample decrease with the increase of laser power.
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