Zhao Jing, Ji Honghong, Wang Tiansheng
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.
National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004, China.
Materials (Basel). 2017 Dec 29;11(1):54. doi: 10.3390/ma11010054.
The high-cycle, push-pull fatigue fracture behavior of high-C, Si-Al-rich nanostructured bainitic steel was studied through the measurement of fatigue limits, a morphology examination and phase composition analysis of the fatigue fracture surface, as well as fractography of the fatigue crack propagation. The results demonstrated that the push-pull fatigue limits at 10⁷ cycles were estimated as 710-889 MPa, for the samples isothermally transformed at the temperature range of 220-260 °C through data extrapolation, measured under the maximum cycle number of 10⁵. Both the interior inclusion and the sample surface constituted the fatigue crack origins. During the fatigue crack propagation, a high amount of secondary cracks were formed in almost parallel arrangements. The apparent plastic deformation occurred in the fracture surface layer, which induced approximately all retained austenite to transform into martensite.
通过测量疲劳极限、对疲劳断口进行形貌检查和相组成分析以及对疲劳裂纹扩展进行断口分析，研究了高碳、富硅铝纳米结构贝氏体钢的高周推拉疲劳断裂行为。结果表明，通过数据外推，对于在220-260℃温度范围内等温转变的样品，在最大循环次数为10⁵次的条件下测量得到，10⁷次循环时的推拉疲劳极限估计为710-889MPa。内部夹杂物和样品表面均构成疲劳裂纹源。在疲劳裂纹扩展过程中，大量二次裂纹几乎平行排列形成。断口表层发生明显塑性变形，致使几乎所有残余奥氏体转变为马氏体。
