Superior resistance to cyclic creep in a gradient structured steel

• 成果类型: Article
• 署名作者: Pan, Qingsong; Ding, Kunqing; Guo, Song; Lu, Ning; Tao, Nairong; Zhu, Ting; Lu, Lei
• 署名单位: Chinese Academy of Sciences; Institute of Metal Research, CAS; University System of Georgia; Georgia Institute of Technology; Chinese Academy of Sciences; University of Science & Technology of China, CAS; Shandong University
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-10527
• DOI: 10.1126/science.adt6666
• 发表日期: 2025-04-04
• 页码: 82-88
• 关键词: stainless-steel; aisi 316l; 300 k; plasticity; fatigue; stress; nucleation; substructure; mechanism; strength

摘要

Cyclic creep, or ratcheting, is a severe form of fatigue deformation caused by cumulative unidirectional plastic strain under asymmetrical stress cycling with a nonzero mean stress. It often causes premature failure of structural materials, and enhancing ratcheting resistance is a challenge in materials engineering. We demonstrate superior ratcheting resistance in high-strength austenitic stainless steel with a gradient hierarchy of dislocation cells. The ratcheting rate is two to four orders of magnitude lower than for coarse-grained counterparts. Its resistance results from sustained microstructural refinement through deformation-induced coherent martensitic transformations to hexagonal close-packed nanolayers within stable dislocation cells. The progressively refined microstructure mitigates cyclic softening and suppresses strain localization during stress cycling, thus reducing ratcheting strain. The gradient dislocation architecture represents a promising design for high-strength, ratcheting-resistant materials.