Evolution of Precipitates of S31042 Heat Resistant Steel During 700 ℃ Aging

• Published in: 钢铁研究学报：英文版 2013, Vol.20 (10), p.113-121
• Main Author: WANG Jing-zhong LIU Zheng-dong BAO Han-sheng CHENG Shi -chang
• Format: Article
• Language: English
• Subjects: M23C6; 元素偏析; 扫描电子显微镜; 析出物; 老化时间; 老化状态; 耐热钢; 进化过程
• ISSN: 1006-706X; 2210-3988

The evolution of precipitates of S31042 steel during 700 ℃ aging was investigated by using a scanning elec- tron microscope, a transmission electron microscope, and electron energy spectrum technology. The various combi nations of M23C6, MX, NbCrN, and σ and G phases in the steel were found at different aging states. In the begin ning of aging, M23C6 precipitates swiftly along the grain boundaries. When the aging time exceeds 6 000 h, precipita- ted M23C6 carbides along the grain boundaries turn to be granular. It was found that Si element segregates to grain boundaries during above process, which may enhance the granular shape of M23C6 carbides and its transformation to and G phases. When the aging time exceeds 10 000 h, various shaped a phase and granular G phase appear along the grain boundaries and there are no continuous M23C6 carbides along the grain boundaries. Meanwhile, a large quantity of granular M23C6 carbides and a minor amount of G phase precipitate near the grain boundaries. Based on the segre- gation of silicon to the grain boundaries, a precipitation evolution model during aging was concluded.