Microstructure and Mechanical Properties of Large-diameter X70 Induction Bend Pipes

Two large-diameter X70 induction bend pipes with flexibility of 25° and 36° were trial-produced by local quenching and whole temper technics, using longitudinally submerged arc welded pipe as materials, and controlling the parameter of processing strictly. And the mechanical property and microstructure of the produced X70 induction bend pipes were tested. The results show that the microstructure of the two trial-produced X70 induction bend pipes was bainite + ferrite + pearlite, tension properties of them could meet the requirement of X70 steel pipe, and the impact toughness was also excellent at -60 ℃.