Ping-Jui YCheng-Yao HYi-Ting LYu-Cheng SHUNG-WEI YENCheng-An HShing-Hoa WJien-Wei YWen-Hsing HTzy-Rong LTai-Wen H.2022-11-162022-11-16202202540584https://www.scopus.com/inward/record.uri?eid=2-s2.0-85124017715&doi=10.1016%2fj.matchemphys.2022.125804&partnerID=40&md5=93c2091c301b8057982fccb57ebd4c33https://scholars.lib.ntu.edu.tw/handle/123456789/625354This 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. © 2022 Elsevier B.V.Allotriomorphic δ; Dual-phase stainless steel; Micro-strain; Reverted austeniteAge hardening; Austenite; Ferrite; Martensite; Microstructure; Precipitation (chemical); Solid solutions; Steel research; X ray powder diffraction; Allotriomorphic δ; Crystalline characteristic; Dual phase; Dual phasis; Dual-phase stainless steel; Lath martensite; Micro-strain; Phase precipitations; Precipitation-hardening stainless steel; Reverted austenite; Crystal structurejournal article10.1016/j.matchemphys.2022.1258042-s2.0-85124017715