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在应力比为0.1、恒幅加载载荷下,对低碳贝氏体ADB610钢手工电弧焊焊接接头母材区、热影响区和焊缝区采用CT(紧凑拉伸)试样进行疲劳裂纹扩展试验研究。采用两步七点递增多项式拟合方法计算疲劳裂纹扩展速率(da/dN),并计算应力强度因子范围(ΔK),分别将母材区、热影响区和焊缝区每个试样的(da/dN)和(ΔK)数据进行了回归拟合,得到了以Paris公式表达的ADB610钢母材区、热影响区、焊缝区(da/dN)与(ΔK)的关系式。并将这三区域中多个试样Paris公式中的参数取均值,得到三区域均值裂纹扩展速率表达式。结果表明,在裂纹扩展的初期和中期,母材区的裂纹扩展速率最快,焊缝区的裂纹扩展速率最慢;在裂纹扩展末期,三区域的裂纹扩展快慢相当。
The fatigue crack propagation test was carried out on the base metal, heat-affected zone and weld zone of low-carbon bainite ADB610 steel under the condition of constant stress load of 0.1 and constant amplitude load. the study. The fatigue crack growth rate (da / dN) was calculated by two steps and seven points increasing polynomial fitting method, and the stress intensity factor range (ΔK) was calculated. The fatigue crack growth rate da / dN) and (ΔK) were fitted by regression fitting. The relationship between base metal area, heat affected zone and weld zone (da / dN) and (ΔK) in ADB610 steel expressed by Paris formula was obtained. The parameters in the Paris formula of the three samples in these three regions are averaged to obtain the expression of average crack propagation rate in the three regions. The results show that the crack growth rate of the base metal zone is the fastest and the crack propagation rate of the weld zone is the slowest in the initial and middle stages of crack propagation. The crack growth rate in the three zones is similar at the end of crack propagation.