Abstract:

A refined method was proposed to identify the material parameters of a weld line based on the DIC technique and hardness test.According to the metallographic test and hardness test,the regions of the TWB were divided into the weld zones,heat affected zones,base metal zones according to hardness values.The values of the major and minor strain on which localized
necking occured were obtained by DIC technique,and the hardness values of the weld zone were gained by the hardness test.Then,the relationship of the strain hardening
exponent n and the major and minor strain were obtained according to plasticity
theories.In addition,the relationship of strength coefficient  K and hardness
values were  also derived.Thus,the material parameters of weld zone and two heat affected zones
were obtained with the derived theoretical formula.Examples based on finite
element simulation and experiments were used to verify the accuracy of this method,
and the results show that the refined method is better than the traditional
method,and the investigation has certain reference values for engineering analyses.

Key words: DIC(digital image correlation), hardness, weld line, tailor-welded blank(TWB)

摘要：

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提出了一种基于数字图像相关(digital image correlation,DIC)技术和硬度试验的焊缝材料参数识别方法。首先根据金相试验和硬度试验将拼焊板分为焊缝区、热影响区和母材区,并采用DIC技术和硬度试验分别获取拼焊板各区域的主次应变值和硬度值。然后根据塑性力学理论推导出应变硬化指数n与主次应变值的计算公式以及强度系数K与硬度值的计算公式。通过推导出的理论计算公式，分别求出焊缝区和两个热影响区的材料参数。实例验证表明，该方法比传统方法具有更高的精度。

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关键词: 数字图像相关, 硬度, 焊缝, 拼焊板