Effects of Yttrium on Microstructure Stability and Tensile Properties of China Low Activation Martensitic Steel

• Published in: Metals (Basel ) Vol. 9; no. 4; p. 446
• Main Authors: Qiu, Guoxing, Zhan, Dongping, Li, Changsheng, Qi, Min, Yang, Yongkun, Jiang, Zhouhua, Zhang, Huishu
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.04.2019
• Subjects: Acids; Aging; Aging (metallurgy); Alloys; CLAM steel; DBTT; Electron backscatter diffraction; Electron microscopy; Grain boundaries; Grain boundary migration; Impact strength; Laves phase; Martensitic stainless steels; Mechanical properties; mechanical property; Microstructure; Nuclear energy; Nuclear power plants; R&D; Research & development; Scanning electron microscopy; Stability; Steel; Temperature; Tensile properties; Toughness; Yttrium; United States > US; China; Germany
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met9040446

This study investigated the microstructural stability and mechanical properties exhibited by China low activation martensitic (CLAM) steels with different yttrium (Y) contents over 3000 h of aging at 550 °C. Scanning electron microscopy, electron backscatter diffraction analysis, and transmission electron microscopy were employed to investigate the microstructural evolution of the steels. Results indicated that grain boundary migration was slow and the Laves phase precipitation was delayed in Y-containing steels. Grain boundaries at different angles in 0Y and 6Y CLAM steels were significantly affected, and those in 36Y and 71Y alloys exhibited negligible changes during the long-term thermal aging. Moreover, Y contents had appreciable effects on the strength and toughness of the aged steels. The stable microstructure of Y-containing CLAM alloys is responsible for improved strength and impact toughness during aging.