Acta Metallurgica Sinica (English Letters) ›› 2022, Vol. 35 ›› Issue (10): 1673-1687.DOI: 10.1007/s40195-022-01401-x

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Influence of Selective Laser Melting Process Parameters on Microstructure and Properties of a Typical Ni-Based Superalloy

Zhen Lu1, Chengcai Zhang1(), Nana Deng2, Haiping Zhou2, Ruirui Fang2, Kuidong Gao2, Yukuo Su3, Hongbin Zhang2()   

  1. 1School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
    2College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266590, China
    3Jier Machine-Tool Group Co. Ltd, Jinan 250022, China
  • Received:2021-11-10 Revised:2022-01-05 Accepted:2022-01-05 Online:2022-04-09 Published:2022-04-09
  • Contact: Chengcai Zhang,Hongbin Zhang
  • About author:Hongbin Zhang, skzhanghongbin@163.com
    Chengcai Zhang, chengcai96a@163.com;

Abstract:

The influence of selective laser melting (SLM) process parameters on the microstructure and mechanical properties of a typical Ni-based superalloy was researched. The optimum parameters of P = 170 W, V = 0.8 m/s were determined, under which the SLMed samples exhibited both the largest relative density of 99.57% and the best mechanical properties, including the microhardness (329.3 ± 3.8 HV), yield strength (726 ± 8.1 MPa), ultimate tensile strength (900 ± 5.9 MPa) and elongation ((31.9 ± 0.24)%). The average grain size ranges of SLMed samples are from 15.2 to 17.4 μm, with a typical mixed grain structure. Owing to the high cooling rate and remelting during SLM process, a large number of low-angle grain boundaries (LAGBs), dislocations and sub-grains were formed, and the fraction of LAGBs reached above 65%. At the same time, the content of low-Σ coincidence site lattice (CSL) boundaries was mostly less than 1%, while there was almost no γ′ phase precipitated in the matrix. The texture of SLMed samples was weak, and there was no obvious preferred growth direction. Combining with the microstructure characterization, both grain refinement strengthening and dislocation strengthening were considered as the main strengthening mechanisms. Moreover, the fracture mechanism of the optimum sample belonged to ductile fracture.

Key words: Selective laser melting, Ni-based superalloy, Relative density, Microstructure, Mechanical property