童乐为, 任珍珍, 景爽, 牛立超. 高强度结构钢系列的疲劳裂纹扩展速率试验研究[J]. 工程力学, 2020, 37(12): 191-201, 212. DOI: 10.6052/j.issn.1000-4750.2020.04.0246
引用本文: 童乐为, 任珍珍, 景爽, 牛立超. 高强度结构钢系列的疲劳裂纹扩展速率试验研究[J]. 工程力学, 2020, 37(12): 191-201, 212. DOI: 10.6052/j.issn.1000-4750.2020.04.0246
TONG Le-wei, REN Zhen-zhen, JING Shuang, NIU Li-chao. EXPERIMENTAL STUDY ON FATIGUE CRACK GROWTH RATE OF HIGH STRENGTH STRUCTURAL STEEL SERIES[J]. Engineering Mechanics, 2020, 37(12): 191-201, 212. DOI: 10.6052/j.issn.1000-4750.2020.04.0246
Citation: TONG Le-wei, REN Zhen-zhen, JING Shuang, NIU Li-chao. EXPERIMENTAL STUDY ON FATIGUE CRACK GROWTH RATE OF HIGH STRENGTH STRUCTURAL STEEL SERIES[J]. Engineering Mechanics, 2020, 37(12): 191-201, 212. DOI: 10.6052/j.issn.1000-4750.2020.04.0246

高强度结构钢系列的疲劳裂纹扩展速率试验研究

EXPERIMENTAL STUDY ON FATIGUE CRACK GROWTH RATE OF HIGH STRENGTH STRUCTURAL STEEL SERIES

  • 摘要: 为研究高强度结构钢的疲劳性能,对Q460C、Q550D、Q690D和Q960D四种国产高强钢母材进行了疲劳裂纹扩展速率试验。每种钢材均取3个10 mm厚的C(T)紧凑拉伸试样,在应力比R=0.1的条件下施加恒幅疲劳荷载,利用显微镜目测记录每个试样的裂纹扩展长度a和对应的循环次数N。对每个试样的试验结果,分别采用七点递增多项式法、Smith法和割线法进行处理,计算裂纹扩展速率和应力强度因子幅值数据组,得到对应于Paris公式中的参数,比较不同方法拟合结果的优劣性并分析原因。再将同种钢材三个试样的数据合成一组,同样采用三种方法计算,并与单试样数据的结果作对比。最后给出了四种钢材Pairs公式中的疲劳裂纹扩展速率参数,并与其他文献中各种结构钢疲劳裂纹扩展速率的参数值进行对比评价。研究表明该文高强度结构钢的疲劳裂纹扩展速率会随着强度的提高而降低,并且这四种高强钢的疲劳裂纹扩展速率都比BS7910中针对普通强度结构钢推荐的疲劳裂纹扩展速率要低。

     

    Abstract: Fatigue crack growth rate tests of the domestic Q460C, Q550D, Q690D and Q960D base metal were conducted firstly in order to study the fatigue behavior of high-strength structural steel. Three C(T) compact tensile samples with the thickness of 10 mm were taken from each grade of steel, and then constant amplitude fatigue load was applied under the condition of stress ratio R=0.1. During the tests, the crack growth length a was measured by microscopic visual inspection, and the corresponding number of cycles N was recorded. For each sample, three methods, i.e., seven-point incremental polynomial method, Smith method and secant method, were adopted to fit the values of crack growth rate and stress intensity factor range data sets, so that material parameters in Paris formula could be obtained through regression. The advantages of different methods were compared and analyzed. Furthermore, data of three samples for the same grade of steel were combined into a group using the same three methods to calculate, and the consequent results were compared with those of single sample data. Finally, parameters in Paris formula of the four grades of steel were given and compared with the values of different types of structural steel in other literatures. This investigation indicates that the fatigue crack growth rates for the four grades of high-strength structural steel decrease with the increase of yield strength, and all of them are lower than that recommended for ordinary strength structural steel in BS7910.

     

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