(1. School of Metallurgical and Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China) （2. State Key Laboratory of Porous Metal Materials, Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China)
H13 steel is the most widely used and representative hot-working tool steel. The use of selective electron beam melting (SEBM) technology to form H13 steel can effectively solve the problem of unsatisfactory tissue uniformity, and it has considerable mechanical properties. In this paper, H13 steel was prepared by changing the electron beam current of SEBM technology, and the densities, microstructures and hardness of the formed parts were characterized by electron densitometry, X’ray diffractometer (XRD), scanning electron microscope (SEM) and micro-Vickers hardness tester. The effects of the electron beam current on the microstructure evolution and mechanical properties were investigated. The results show that the H13 steel formed by different electron beam current mainly has dispersed nano-sized micropores, local micro-sized micropores and poor fusion areas. The microstructure is mainly composed of martensite, residual austenite and carbide. With the increase of the electron beam current, the martensite will undergo lattice distortion and the matrix strength will increase. And if the electron beam current continues to be increased, the martensite will gradually dissolve, the matrix will recovery and recrystallization, while secondary carbide will be diffusely precipitated and the matrix strength will stabilize.