Effect of microstructural evolution by isothermal aging on the mechanical properties of 9Cr-1WVTa reduced activation ferritic/martensitic steels

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• 作者：Min-Gu Park^a ; Chang-Hoon Lee^a ; ^{lee1626@kims.re.kr} ; Joonoh Moon^a ; Jun Young Park^a ; Tae-Ho Lee^a ; Namhyun Kang^b ; Hyoung Chan Kim^c
• 关键词：RAFM steel ; Aging ; Grain boundary carbide ; Spheroidization ; Charpy impact toughness
• 刊名：Journal of Nuclear Materials
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：485
• 期：Complete
• 页码：15-22
• 全文大小：5702 K
• 卷排序：485

文摘

The influence of microstructural changes caused by aging condition on tensile and Charpy impact properties was investigated for reduced activation ferritic-martensitic (RAFM) 9Cr-1WVTa steels having single martensite and a mixed microstructure of martensite and ferrite. For the mixed microstructure of martensite and ferrite, the Charpy impact properties deteriorated in both as-normalized and tempered conditions due to the ferrite and the accompanying M23C6 carbides at the ferrite grain boundaries which act as path and initiation sites for cleavage cracks, respectively. However, aging at 550 °C for 20–100 h recovered gradually the Charpy impact toughness without any distinct drop in strength, as a result of the spheroidization of the coarse M23C6 carbides at the ferrite grain boundaries, which makes crack initiation more difficult.