HIGH-STRENGTH STEEL, PRODUCTION METHOD THEREFOR, STEEL PIPE, AND PRODUCTION METHOD FOR STEEL PIPE

摘要

Provided is a technology for manufacturing a high-strength steel pipe that is at least API grade X100 and is for transporting steam. The high-strength steel uses a specified component composition and is characterized by: Ti/N being at least 2.0 and less than 4.0; X (%) in formula (1) being at least 0.90%; the bainite fraction being at least 70%, and the tensile strength at 350°C being at least 760 MPa. X = 0.35 Cr + 0.9 Mo + 12.5 Nb + 8 V (1). The chemical symbols in formula (1) indicate the content (% by mass) of each element. 0 is substituted if an element is not included.