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闪光对焊是冷轧带钢生产线上的重要工序。但在焊接接头中常有“灰斑”缺陷存在,严重影响焊接质量。本文用扫描电子显微镜和X光能谱仪对中碳结构钢焊接接头中的“灰斑”缺陷进行了研究。为合理选择焊接工艺、改善接头质量提供了依据。主要试验结果和讨论如下: 1.低倍分析表明,“灰斑”缺陷有两种形式:一种为细长条形,一种为园片形。条形“灰斑”可以贯穿整个断口平面,其延伸方向即为对焊顶锻中金属挤压流变的方向。在冷弯样品中,无缺陷区的断口形貌呈准解理特征。
Flash butt welding is an important process in the cold rolled strip production line. However, often in the welded joints, “gray spots” defects exist, seriously affecting the quality of welding. In this paper, the “gray spot” defects in welded joints of carbon structural steel were studied by scanning electron microscopy and X-ray energy dispersive spectroscopy. The reasonable choice of welding process, improve the quality of joints provided. The main results and discussion are as follows: 1. The low magnification analysis shows that there are two kinds of defects of “gray spot”: one is slender strip and the other is disk-shaped. Bar-shaped “gray spots” can penetrate the fracture surface, the extension of the direction of the metal extrusion is the top of the weld forging rheological direction. In the cold-formed samples, the fracture surface of the defect-free zone is quasi-cleavage.