Hardening steels by the generation of transient phase using additive manufacturing. (June 2019)

• Record Type: Journal Article
• Authors: Huang, E-Wen; Lee, Soo Yeol; Jain, Jayant; Tong, Yang; An, Ke; Tsou, Nien-Ti; Lam, Tu-Ngoc; Yu, Dunji; Chae, Hobyung; Chen, Shi-Wei; Chen, Shih-Min; Chou, Hung-Sheng
• Is Part Of: Intermetallics. Volume 109(2019:Jun.)
• Page Start: 60
• Page End: 67
• Publication Date: 2019-06
• Subjects: Neutron diffraction -- Additive manufacturing -- Selective laser melting -- Stainless steel -- Anisotropy; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2019.03.004
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: In the present work, the tensile properties of 15–5 PH steel fabricated by selective laser melting (SLM) were examined with respect to the transient austenite phase. Compared with the 8%-transient-phase sample, the 18%-transient-phase one shows higher ultimate tensile strength and relatively low yield strength, as well as hardening behavior. We conducted in-situ neutron-diffraction study to examine the microstructure evolution for mechanistic understanding. After applying the external load, most non-equilibrium, retained austenite in the 8%-transient-phase sample transforms before the yield strength, whereas in the 18%-transient-phase sample only 50% of the austenite transforms. Accompanying with the phase transformation, a decrease in the dislocation density and the dislocation strain energy-assisted phase transformation of the ferrite phase are found in the 8%-transient-phase sample even before yielding, which, however, is not the case in the 18%-transient-phase sample. The study demonstrates the SLM enables tuning the amount of transient-phase ratio and coherency between phases to realize a mechanical property control for additive manufactured steel. Highlights: The tensile behavior was examined for 8%- and 18%-transient-phase additive manufacturing steels using in-situ neutron diffraction. The 18%-transient-phase sample exhibited higher ultimate tensile strength and low yield strength. The 18%-transient-phase specimen with more non-equilibrium γ-phase revealed a more profound strain hardening effect.