FERRITIC STAINLESS STEEL WELDED PIPE EXCELLENT IN PIPE EXPANDING WORKABILITY

摘要

A ferritic stainless steel pipe, which is producing by subjecting a raw material plate, which has a chemical composition, in mass %, that C: 0.001 to 0.015 %, N: 0.001 to 0.020 %, Cr: 11 to 25 %, Mo: 0.01 to 2.0 %, one or more of Ti and Nb: 0.05 to 0.5 %, B: 0.0003 to 0.0030 % and the balance: Fe and inevitable impurities, exhibits an elongation in the direction of the circumference as a raw material plate for a welded steel pipe of 30 % or more, and has an average r value of 1.5 or more, to forming, welding, correcting of 0.5 to 2.0 % in terms of a circumference, and optionally, annealing at a temperature of 700 to 850°C, so as for the resulting pipe to have a difference of a weld zone and a base material zone in Vickers hardness of 10 to 40, a (a thickness of the bead in a weld zone/a thickness of a base material zone) of 1.05 to 1.3 and an elongation of the base material zone of a welded pipe in the circumference direction of 15 % or more.