Improving Fatigue Properties of 316L Stainless Steel Welded Joints by Surface Spinning Strengthening

IF 2.9 2区材料科学 Q2 METALLURGY & METALLURGICAL ENGINEERING

Acta Metallurgica Sinica-English Letters Pub Date : 2024-02-29 DOI:10.1007/s40195-024-01668-2

Dongqiqiong Wang, Qiang Wang, Xiaowu Li, Zhefeng Zhang

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Abstract

The surface spinning strengthening (3S) mechanism and fatigue life extension mechanism of 316L stainless steel welded joint were systematically elucidated by microstructural analyses and mechanical tests. Results indicate that surface gradient hardening layer of approximately 1 mm is formed in the base material through grain fragmentation and deformation twin strengthening, as well as in the welding zone composed of deformed δ-phases and nanotwins. The fatigue strength of welded joint after 3S significantly rises by 32% (from 190 to 250 MPa), which is attributed to the effective elimination of surface geometric defects, discrete refinement of δ-Fe phases and the appropriate improvement in the surface strength, collectively mitigating strain localization and surface fatigue damage within the gradient strengthening layer. The redistributed fine δ-Fe phases benefited by strong stress transfer of 3S reduce the risk of surface weak phase cracking, causing the fatigue fracture to transition from microstructure defects to crystal defects dominated by slip, further suppressing the initiation and early propagation of fatigue cracks.

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通过表面旋压强化提高 316L 不锈钢焊接接头的疲劳性能

通过微观结构分析和力学试验，系统地阐明了 316L 不锈钢焊接接头的表面旋转强化（3S）机理和疲劳寿命延长机理。结果表明，通过晶粒破碎和变形孪生强化，在母材中形成了约 1 mm 的表面梯度硬化层，在焊接区也形成了由变形 δ 相和纳米晶组成的表面梯度硬化层。3S 后焊接接头的疲劳强度显著提高了 32%（从 190 兆帕提高到 250 兆帕），这归功于表面几何缺陷的有效消除、δ-铁相的离散细化以及表面强度的适当提高，它们共同减轻了梯度强化层内的应变局部化和表面疲劳破坏。通过 3S 的强应力传递而重新分布的精细 δ-Fe 相降低了表面弱相开裂的风险，使疲劳断裂从微观结构缺陷过渡到以滑移为主的晶体缺陷，进一步抑制了疲劳裂纹的产生和早期扩展。

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来源期刊

Acta Metallurgica Sinica-English Letters METALLURGY & METALLURGICAL ENGINEERING-

CiteScore

6.60

自引率

14.30%

发文量

122

审稿时长

2 months

期刊介绍： This international journal presents compact reports of significant, original and timely research reflecting progress in metallurgy, materials science and engineering, including materials physics, physical metallurgy, and process metallurgy.