Crystalline characteristics of a dual-phase precipitation hardening stainless steel in quenched solid solution and aging treatments

• Published in: Materials chemistry and physics Vol. 280; p. 125804
• Main Authors: Yu, Ping-Jui, Huang, Cheng-Yao, Lin, Yi-Ting, Su, Yu-Cheng, Yen, Hung-Wei, Hsu, Cheng-An, Wang, Shing-Hoa, Yeh, Jien-Wei, Hou, Wen-Hsing, Lin, Tzy-Rong, Hsu, Tai-Wen
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.03.2022; Elsevier BV
• Subjects: Aging; Aging (metallurgy); Allotriomorphic δ; Austenite; Delta ferrite; Dual phase steels; Dual-phase stainless steel; Duplex stainless steels; Martensite; Martensitic stainless steels; Micro-strain; Microstrain; Microstructure; Misalignment; Precipitation hardening; Precipitation hardening steels; Reverted austenite; Solid solutions; Solution heat treatment; Stainless steel; Dual-phase stainless steel; Micro-strain; Reverted austenite; Allotriomorphic δ
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2022.125804

This study investigated the development of the microstructures and aging reactions in a new dual-phase (allotriomorphic δ + γ) 17–4 precipitation-hardened (PH) stainless steel (SS) alloy. The 17–4 PH alloy, a martensitic stainless steel containing Cu (3–5 wt.%), was subjected to solid solution treatment followed by quenching using oil, H2O, or liquid N2. The microstructures of the steel specimens were primarily composed of lath martensite and allotriomorphic δ-ferrite. X-ray diffraction analysis indicated that the structures consisted entirely of bcc phase peaks. During aging at 560 and 600 °C, the local microstrain was released because of the tempering of the lath martensite and the formation of reverted austenite, resulting in a shift in the kernel's average misorientation distribution toward lower angles. The misorientation associated with the martensite boundaries ranged from 10° to 20° and from 47° to 57° in the packets. In the blocks, it ranged from 50° to 60°. The F1-ferrite approximately followed the Kurdjumov–Sachs orientation relationship with A1-austenite and A2-austenite. ●This is the first report on a new dual-phase (allotriomorphic δ + γ) PHSS.●The microstructure of this material consisted of lath martensite and ALF δ in a quenched solid solution.●The martensite laths followed some variant of the K–S OR with respect to the prior austenite grain.●The fraction of the misorientation angle distribution was concentrated at low (<15°) and high angles (>50°).