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| Manufacturing of high nitrogen stainless steel by Selective Laser Melting with overmixed powders |
| REN Jianbiao，ZHAO Dingguo，SUN Xin，WANG Shuhuan，NI Guolong，LIU Kun |
| （School of Metallurgy and Energy, North China University of Science and Technology, Tangshan 063210, China） |
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Abstract Nitrogen evolution exists in the process of Selective Laser Melting of high nitrogen stainless steel pow‐
der under atmospheric pressure, and qualified high nitrogen stainless steel cannot be effectively made. Stainless
steel powder with nitrogen content of 1.472% was prepared by overmixing powder method, and the printing form‐
ing experiment of overmixed powders were carried out on Selective Laser Melting equipment. The effect of laser
processing parameters on the nitrogen content, microstructure and mechanical properties of high nitrogen stainless
steel was studied. The experimental results show that high nitrogen stainless steel with more than 0.9% nitrogen
content and certain mechanical properties can be prepared by overmixed powders method. The nitrogen content of
the formed sample is inversely proportional to the laser power, at a scan speed of 1 000 mm/s, laser power is
increased from 200 W to 300 W, nitrogen content decreases from 0.991% to 0.956%. Being directly proportional
to the scan speed, at 225 W laser power, Scan speed is increased from 700 mm/s to 1 000 mm/s, nitrogen content
increases from 0.823% to 0.985%. At 250 W laser power, Scan speed is increased from 700 mm/s to 1 000 mm/s, nitrogen content is increased from 0.817% to 0.970%. The scanning speed has more significant effects on the nitro‐
gen content. At a scan speed of 1 000 mm/s, ranging from 200 to 300 W, with the increase of laser power, the inter‐
nal defects of the sample gradually reduce, the forming quality becomes better, and the tensile strength increases
first and then decreases. The optimization results show that the scanning speed of 1 000 mm/s and laser power of
275 W are the optimal parameters. The forming quality of high nitrogen stainless steel is the best, the number of
internal defects is the least, and the comprehensive tensile properties are good, the tensile strength and yield
strength are 1 001.7 MPa and 363.8 MPa, respectively, while the nitrogen content is higher than 0.9%.
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Received: 28 July 2022
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Corresponding Authors:
赵定国（1981—），男，博士，教授，博士生导师，主要研究方向为炼钢新技术及品种钢冶炼。
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2023, Vol. 33 
