基于在线观察的激光焊接凝固热裂纹敏感性研究

激光焊接过程中较快的冷却速度可能会加剧凝固热裂纹的发生。目前对于激光焊接过程中凝固热裂纹敏感性的系统研究还较少，如何准确测量焊接凝固热裂纹发生的临界应变和温度是获得热裂纹敏感性数据的关键。利用基于高速高倍在线摄像的U型热裂纹实验，捕捉到激光焊接过程中凝固热裂纹发生的瞬间，并通过跟踪测量热裂纹尖端附近两点的位移变化获得凝固热裂纹发生的临界应变；同时，在焊接过程中采用在线观察热电偶投入法对焊接熔池后端的温度变化进行了测量。通过改变U型热裂纹实验的拉伸载荷，获得不同温度下热裂纹发生时的临界应变，从而构建表征凝固热裂纹敏感性的韧性曲线。

Abstract

The rapid cooling during laser welding can prompt the occurrence of solidification cracking, however, few study is found on systematic research of solidification cracking during laser welding. It is the key to accurately measure the critical strain and temperature of the crack in order to know solidification cracking susceptibility. By using U-type hot cracking test with in-situ observation method, the occurrence of solidification cracking is captured clearly by high-speed-high-magnification camera. With the in-situ observation method, the local critical strain of crack is measured by tracking the displacement of two reference points near the crack; the local temperature of crack is measured by inserting the thermocouple to the trailing edge of the weld pool. Local critical strains at different temperatures are obtained under different tensile loads in U-type hot cracking test. The high temperature ductility curve is achieved accurately.

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温鹏, 荻崎贤二, 山本元道. 基于在线观察的激光焊接凝固热裂纹敏感性研究[J]. 中国激光, 2011, 38(6): 0603005. Wen Peng, Shinozaki Kenji, Yamamoto Motomichi. Evaluation of Solidification Cracking Susceptibility during Laser Welding by In-situ Observation Method[J]. Chinese Journal of Lasers, 2011, 38(6): 0603005.

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