Enhanced resistance to fatigue crack propagation in metastable austenitic stainless steel by nanotwin bundles

SCRIPTA MATERIALIA

卷:201

Article

Matsushita, Aya¹  Mine, Yoji¹  Takashima, Kazuki¹ 

[1] Kumamoto Univ, Dept Mat Sci & Engn, Chuo Ku, 2-39-1 Kurokami, Kumamoto 8608555, Japan

关键词: Nanotwins;    Austenitic steels;    Deformation structure;    Fatigue;    Martensitic phase transformation;   

DOI  :  10.1016/j.scriptamat.2021.113976

来源: Elsevier

【 摘 要 】

Microstructure-sensitive fatigue crack growth in 304 metastable austenitic stainless steel containing nan-otwin bundles was studied using a miniature compact tension specimen combined with post-fatigue met-allographic examinations. The single-variant nanotwinned specimens exhibited high crack growth resis-tance compared to the coarse-grained specimen without nanotwin bundles, regardless of lamellar orien-tation. In the nanotwin bundles, martensite variants are formed with the habit plane parallel to the twin plane during crack propagation. Even when the crack propagates along the twin boundary, it tends to proceed by activation of multiple slip systems into the formed martensite phase, which inhibits brittle twin boundary separation. Post-fatigue transmission electron microscopy revealed that detwinning oc-curred ahead of the crack tip. Therefore, introducing nanotwin bundles into the metastable austenitic steel changes the course of damage accumulation through detwinning and martensite formation, enhanc-ing the fatigue crack growth resistance. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

【 授权许可】

Free