Three-dimensional study of grain boundary engineering effects on intergranular stress corrosion cracking of 316 stainless steel in high temperature water

JOURNAL OF NUCLEAR MATERIALS

卷:498

Article

Liu, Tingguang^1,2  Xia, Shuang²  Bai, Qin²  Zhou, Bangxin²  Zhang, Lefu³  Lu, Yonghao¹  Shoji, Tetsuo^1,4 

[1] Univ Sci & Technol Beijing, Natl Ctr Mat Serv Safety, Beijing 100083, Peoples R China

[2] Shanghai Univ, Sch Mat Sci & Engn, Shanghai 200072, Peoples R China

[3] Shanghai Jiao Tong Univ, Sch Nucl Sci & Engn, Shanghai 200240, Peoples R China

[4] Tohoku Univ, NICHe, Frontier Res Initiat, Sendai, Miyagi 9808579, Japan

关键词: 316 stainless steel;    Intergranular stress corrosion cracking;    Grain boundary engineering;    3D characterization;    Grain-cluster;   

DOI  :  10.1016/j.jnucmat.2017.10.004

来源: Elsevier

【 摘 要 】

The intergranular cracks and grain boundary (GB) network of a GB-engineered 316 stainless steel after stress corrosion cracking (SCC) test in high temperature high pressure water of reactor environment were investigated by two-dimensional and three-dimensional (3D) characterization in order to expose the mechanism that GB-engineering mitigates intergranular SCC. The 3D microstructure shown that the essential characteristic of the GB-engineered microstructure is formation of many large twin-boundaries as a result of multiple-twinning, which results in the formation of large grain-clusters. The large grain-clusters played a key role to the improvement of intergranular SCC resistance by GB-engineering. The main intergranular cracks propagated in a zigzag along the outer boundaries of these large grain-clusters because all inner boundaries of the grain-clusters were twin-boundaries (Sigma(3)) or twin-related boundaries (Sigma(3n)) which had much lower susceptibility to SCC than random boundaries. These large grain-clusters had tree-ring-shaped topology structure and very complex morphology. They got tangled so that difficult to be separated during SCC, resulting in some large crack-bridges retained in the crack surface. (C) 2017 Elsevier B.V. All rights reserved.

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