Ma Zhiwei, Liu Jiabin, Wang Gang, Wang Hongtao, Wei Yujie, Gao Huajian
LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, P.R. China.
Faculty of Engineering, Zhejiang University, Hangzhou 310027, China.
Sci Rep. 2016 Feb 24;6:22156. doi: 10.1038/srep22156.
Steels are heavily used in infrastructure and the transportation industry, and enhancing their fatigue resistance is a major challenge in materials engineering. In this study, by introducing a gradient microstructure into 304 austenitic steel, which is one of the most widely used types of stainless steel, we show that a strength gradient substantially enhances the fatigue life of the material. Pre-notched samples with negative strength gradients in front of the notch's tip endure many more fatigue cycles than do samples with positive strength gradients during the crack initiation stage, and samples with either type of gradient perform better than do gradient-free samples with the same average yield strength. However, as a crack grows, samples with positive strength gradients exhibit better resistance to fatigue crack propagation than do samples with negative gradients or no gradient. This study demonstrates a simple and promising strategy for using gradient structures to enhance the fatigue resistance of materials and complements related studies of strength and ductility.
钢材在基础设施和交通运输行业中大量使用，提高其抗疲劳性能是材料工程中的一项重大挑战。在本研究中，通过在304奥氏体钢（一种使用最广泛的不锈钢类型）中引入梯度微观结构，我们表明强度梯度显著提高了材料的疲劳寿命。在裂纹萌生阶段，缺口尖端前方具有负强度梯度的预切口试样比具有正强度梯度的试样承受更多的疲劳循环，并且两种梯度类型的试样都比具有相同平均屈服强度的无梯度试样表现更好。然而，随着裂纹扩展，具有正强度梯度的试样比具有负梯度或无梯度的试样表现出更好的抗疲劳裂纹扩展能力。本研究展示了一种利用梯度结构提高材料抗疲劳性能的简单且有前景的策略，并补充了强度和延展性的相关研究。
