Fracture toughness determination from load-line displacement of 3-point bend specimen using 3D digital image correlation method for CLF-1 steel
Fracture toughness determination from load-line displacement of 3-point bend specimen using 3D digital image correlation method for CLF-1 steel
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DOI：
10.1016/j.jnucmat.2020.152565
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发表时间：
2021
影响因子：
3.1
通讯作者：
Wangzi Zhang;Yao Xie;Lei Peng;H. Liao;Y. Wan
中科院分区：
文献类型：
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作者：
Wangzi Zhang;Yao Xie;Lei Peng;H. Liao;Y. Wan
载荷线位移(LLD)是用J积分确定核结构材料断裂韧性的基本方法。为了获得准确的LLD，采用三维数字图像相关(DIC)方法，在中国低活度铁素体/马氏体钢(CLF-1)的小型三点弯曲(3点弯曲)试件上，测量了不同加载点对应的不同LLD，并对载荷-位移曲线和J积分的测定进行了分析。结果表明，LLD值越大，J积分值越高。J积分值随裂纹方向距试件顶端的距离先增大后减小，与LLD的变化规律相似。有趣的是，几乎在中性轴上的加载点的LLD得出峰值J0.2(B)值(250℃时为447和471 kJ/m2,450℃时为270和331 kJ/m2)，接近相应裂口张开位移(CMOD)的值(250℃时为441和470,450℃时为269和332 kJ/m2)。而缺口尖端附近的LLD对应的J0.2(B)值要低得多。建议采用中性轴加载点的LLD来确定3根PB试件的J积分。
Load-line displacement (LLD) is essential for determining fracture toughness in terms of J-integral for nuclear structure materials. To obtain the accurate LLD, using a three-dimensional (3D) digital image correlation (DIC) method, the different LLD corresponding to different load points were measured on the miniature 3-point bend (3 PB) specimens of Chinese low activation ferritic/martensitic (CLF-1) steel in unloading compliance testing, and the load-displacement curves and J-integral determination were analyzed. The results show a higher LLD value generally derives a higher J-integral value. The J-integral values increase and then decrease with the distance from the top of specimen along crack direction, which is similar to the variation of LLD. It is interesting that the LLD of the load point almost at the neutral axis derive the peak J0.2(B)value (447 and 471 kJ/m2at 250°C, 270 and 331 kJ/m2at 450°C), close to the values (441 and 470 at 250°C, 269 and 332 kJ/m2at 450°C) from the corresponding crack mouth opening displacement (CMOD). And the corresponding J0.2(B)values from LLD of points near the notch tip are much lower. The LLD of the load point at the neutral axis was recommended the accurate LLD to determine J-integral of the 3 PB specimens.