基板材料与铺粉速度对激光选区熔化成型m2高速钢的影响

Abstract

This study aims to improve the mechanical properties and microstructure of M 2 highspeed steel tool materials prepared using threedimensional printing technology and promote the development of threedimensional printing technology for metal tool materials. M2 highspeed steel samples were prepared using laser selective melting under different substrate materials and powder feeding speeds. The mechanical properties and microstructure of the samples were characterized and observed. The results show that the thermal expansion coefficient of 316L stainless steel substrate is about 57. 27 % higher than that of M2 highspeed steel substrate. The thermal conductivity of 316L stainless steel substrate is 17. 28 % lower than that of M2 high speed steel substrate, which reduces the thermal stress produced during the preparation process. Remaining stress is released more fully with slow cooling. Therefore, 316L stainless steel substrate is conducive to forming M2 highspeed steel samples. With the decrease of powder feeding speed, the realtime heat treatment time in the printing process will be greatly increased, which leads to a slight decrease in the hardness of the material but a more compact microstructure, a decrease in cracks, pores, and other defects, and an increase in the tensile strength. The Rockwell hardness of the sample obtained by the experiment is up to (58. 97 ± 0. 28) HRC, and the tensile strength can reach (937 ± 118) MPa. The microstructure presents a network structure with many martensite columnar crystals, and the needle width is less than 1 μm. The main phases include α -Fe, austenite, martensite, and MC carbides.