Microstructure evolution and mechanical properties of Hastelloy X alloy produced by Selective Laser Melting

• Published in: High temperature materials and processes Vol. 39; no. 2020; pp. 124 - 135
• Main Authors: Zhonggang, Sun, Shuwei, Ji, Yanhua, Guo, Yichen, Lu, Lili, Chang, Fei, Xing
• Format: Journal Article
• Language: English
• Published: Berlin De Gruyter 27.05.2020; Walter de Gruyter GmbH
• Subjects: Evolution; Flux density; Grain size; Hastelloy (trademark); Hastelloy X alloy; Heat treating; Heat treatment; Horizontal orientation; Laser beam melting; laser selective melting; Lasers; Martensite; Mechanical properties; Microstructure; Process parameters; Scanning; Solid solutions; Superalloys; Thickness
• ISSN: 0334-6455; 2191-0324
• DOI: 10.1515/htmp-2020-0032

Selective laser melting (SLM) is considered as an important additive manufacturing (AM) technology which can fabricate parts with complex geometry. However, it is difficult to predict the optimal SLM-parameters of metallic materials. In this study, orthogonal experiments were designed to study the influence of SLM-process parameters on the density and fabricated quality of Hastelloy X superalloy. Moreover, the relationship between microstructure evolution and performance of deposited microstructure was studied after heat treatment. The laser power, scanning speed and energy density have a significant effect on the density of the fabricated parts. The optimal parameters for determining Hastelloy X are 250 W laser power, 500 mm/s scanning speed, 100 μm hatch space, and 30 μmlayer thickness. The deposited microstructure is a lamellar microstructure in the horizontal direction and a columnar crystal in the longitudinal direction, and the microstructure is mainly martensite. After solid-solution and aging treatment, grain grows up. Martensite decomposes and the carbide M C was precipitated during the aging process. The strength of the microstructure decreases slightly due to the growth of grain size.