Cracking Behavior of 304 Stainless Steel during Low Stress Bending Fatigue Separation

YU Zhengyang; SHU Zhankai; WANG Yongfeng; WANG Huan; ZHANG Kaiming; ZHONG Bin; LIU Wenzhuo

doi:10.3969/j.issn.1674-6457.2026.10.015

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (10) : 147-153. DOI: 10.3969/j.issn.1674-6457.2026.10.015

Iron and Steel Forming

Cracking Behavior of 304 Stainless Steel during Low Stress Bending Fatigue Separation

YU Zhengyang¹, SHU Zhankai¹, WANG Yongfeng¹, WANG Huan¹, ZHANG Kaiming¹, ZHONG Bin^2,*, LIU Wenzhuo³

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Abstract

The work aims to solve the problem of unclear cracking behavior of metal bars during low stress separation. Based on Hall-Petch plasticity theory and shear modified Gurson-Tvergaard-Needleman (GTN) model proposed by Zhou, an extended GTN model considering grain size effect was constructed, and the elastic-plastic parameters and model parameters of 304 stainless steel were identified by uniaxial tensile test, reverse solution method and microscopic observation method. On this basis, the numerical simulation method of low stress bending fatigue separation with coupled damage was used to study the mechanism of cracking behavior induced by material damage evolution under low stress bending fatigue separation process. The reliability of extended GTN model theory and finite element numerical simulation considering grain size effect was verified by conducting a precision separation test and relying on cross-section evaluation index and separation time. The cracking behavior of 304 stainless steel bar in the process of low stress bending fatigue separation began with the root of artificially prefabricated annular notch. With the increase of the downward displacement of the hammer head, the hole volume fraction and Mises stress at the root of the annular notch increased. Based on the evaluation index of cross-section, when the pressing displacement of the hammer head was 1.5 mm, the high-efficiency near-net cross-section was obtained. The extended GTN model considering grain size effect can be applied to predict the cracking behavior under low stress precision separation process, which provides theoretical support for the reasonable selection of subsequent separation process parameters.

Key words

low stress precision separation / 304 stainless steel / damage evolution / cracking behavior / GTN model

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YU Zhengyang, SHU Zhankai, WANG Yongfeng, WANG Huan, ZHANG Kaiming, ZHONG Bin, LIU Wenzhuo. Cracking Behavior of 304 Stainless Steel during Low Stress Bending Fatigue Separation[J]. Journal of Netshape Forming Engineering. 2026, 18(10): 147-153 https://doi.org/10.3969/j.issn.1674-6457.2026.10.015

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Funding

Scientific Research Project of Shaanxi Provincial Department of Education (25JK0512, 24JK0499); School-level Scientific Research Fund Project of XIHANG University (2024KY1206)