PLASMA ARC WELDED STEEL PIPE HAVING EXCELLENT FORMABILITY AND ANTI-FATIGUE PROPERTY IN WELDED ZONE, AND METHOD FOR MANUFACTURING THE SAME

摘要

PURPOSE: A plasma arc welding steel pipe and a manufacturing method thereof are provided to obtain the plasma arc welding steel pipe with excellent properties as an inner cladding material and a welding unit having excellent weldability. CONSTITUTION: A plasma arc welding steel pipe comprises a base material and a welding unit. The base material is ferrite stainless steel comprising 0.015wt% or less of C, 0.015wt% or less of N, 1.0wt% or less of Si, 1.0wt% or less of Mn, 15.0-20.0wt% of Cr, 0.15wt% or less of Al, 0.01wt% or less of O, 0.040wt% or less of P, 0.010wt% or less of S, one kind or both two kinds of 0.01-0.5wt% of Nb and 0.01-0.5wt% of Ti, and the rest of Fe and inevitable impurities. The bead width of the welding unit is 1.25-1.65mm, and a protruded portion of an upper bead is 0-0.035mm. The base material additionally includes one or more kinds selected among 2.0wt% or less of Ni, 2.0wt% or less of M, 2.0wt% or less of Cu, and 0.002wt% or less of Ca.