Effects of temperature and strain rate on tensile properties and dynamic strain aging behaviour of LPBF Hastelloy X

• Published in: Additive manufacturing letters Vol. 4; p. 100105
• Main Authors: Li, X, Esmaeilizadeh, R, Jahed, H, Toysarkani, E, Pham, MS, Holdsworth, SR, Hosseini, E
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-2023; Elsevier
• Subjects: Additive manufacturing; Dynamic strain aging; Hastelloy X; High temperature tensile response; Laser powder bed fusion; Laser powder bed fusion; High temperature tensile response; Additive manufacturing; Hastelloy X; Dynamic strain aging
• ISSN: 2772-3690; 2772-3690
• DOI: 10.1016/j.addlet.2022.100105

•The quasi-static tensile response of LPBF Hastelloy X was examined for the temperature range of 22- 800°C and strain rate of 10−4-10−2 s−1.•Higher yield and similar tensile strengths were observed for LPBF HX compared with the conventionally manufactured alloy.•Pronounced evidence of DSA was observed for LPBF Hastelloy X over the temperature range of 300-600°C.•The activation energy of 66 kJ/mol was derived for DSA of LPBF HX compared with 80-130 kJ/mol for the conventionally manufactured HX.
This study compares the tensile response of laser powder bed fusion (LPBF) fabricated Hastelloy X (HX) coupons with those of conventionally manufactured HX over the temperature range of 22-800°C and strain rate of 10−4-10−2 s−1. Comparable ultimate tensile strength and higher yield strengths were observed for LPBF HX. The stress-strain response of LPBF HX showed pronounced evidence of dynamic strain aging (DSA) during tensile testing at temperatures from 300°C to 600°C and also limited evidence of DSA at 200° and 700°C. The transition from type-A/B to type-C DSA for LPBF HX happens at lower temperatures than that for conventionally manufactured HX. Furthermore, the activation energy for DSA is 66 kJ/mol for LPBF HX, which is lower than the reported 80-130 kJ/mol for conventionally manufactured HX. The observed differences in the tensile and DSA responses of the two variants of HX were attributed to the differences in their dislocation microstructure, observed through scanning transmission electron microscopy.