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通过使用宏观观察、金相分析、断口分析和电子背散射衍射(EBSD)等分析手段对高频焊管焊后弯管开裂的原因进行了分析。结果表明焊缝区域晶粒内部的位错的胞状组织和未完成多边形化的亚晶是导致汽车排气管焊缝区域韧性下降、硬度升高的原因,最后在弯管成型时,焊缝处受到拉应力导致开裂。从焊缝处发现的晶粒内存在的大量的未完成多边形化的亚晶这一现象推断出问题所在,通过改进,消除了弯管成型开裂的情况。
The causes of crack after welding of high frequency welded pipes were analyzed by macroscopic observation, metallographic analysis, fracture analysis and electronic backscatter diffraction (EBSD). The results show that the intragranular dislocation cells in the weld zone and the unfinished polygon subgrains are the reasons for the decrease of toughness and the increase of hardness in the weld zone of automobile exhaust pipe. Finally, when the pipe is formed, Tensile stress caused by cracking. From the phenomenon of the large number of unfinished polygonized subgrains present in the grains found at the weld, the problem was ruled out and the problem of elbows forming cracking was eliminated by improvement.