THE ANALYSIS ON THE IMPACT TOUGHNESS ABNORMALITY OF WELDING SEAM OF HIGH FREQUENCY WELDING PIPE

To investigate the reason of the great difference in impact toughness of welding seam of high frequency welding pipe, samples taken from base metal, heat affected zone and welding seam were analyzed through microscopy. The results showed that there was serious band structure in the base metal, overheated structure in heat affected zone and inclusion in welding seam.