To clarify the effect of microstructural changes on the fatigue property of the weld heat‐affected zone (HAZ), low‐ to high‐cycle fatigue tests were conducted on 16 types of simulated HAZ specimens that had been prepared using thermal processes. The results showed the fatigue S‐N curves of the HAZ to be widely scattered as a function of strength level. These fatigue data were divided into two groups: coarse grain (CG) and fine grain (FG) HAZ, when strain amplitude was used to represent S‐N curves. The fatigue data for the CGHAZ group showed a relatively short fatigue life. Based on surface observations, the initiated fatigue crack size of CGHAZ was larger than that of FGHAZ as a function of microstructural unit size. Hence, fatigue crack growth life, which is almost the same as total fatigue life of CGHAZ, decreased.

中文翻译：

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模拟热影响区的组织对低碳钢低至高周疲劳性能的影响

为了阐明微观结构变化对焊缝热影响区（HAZ）疲劳性能的影响，对通过热加工制备的16种模拟HAZ试样进行了低至高循环疲劳试验。结果表明，HAZ的疲劳S-N曲线作为强度水平的函数而广泛散布。当使用应变幅度表示S‐N曲线时，这些疲劳数据分为两组：粗晶粒（CG）和细晶粒（FG）HAZ。CGHAZ组的疲劳数据显示相对较短的疲劳寿命。根据表面观察，作为微观结构单元尺寸的函数，CGHAZ的初始疲劳裂纹尺寸大于FGHAZ的疲劳裂纹尺寸。因此，疲劳裂纹扩展寿命几乎与CGHAZ的总疲劳寿命相同。