MANUFACTURING METHOD OF STEEL WITH EXCELLENT TOUGHNESS OF WELD HEAT AFFECTED ZONE

摘要

PURPOSE: A method of manufacturing a steel member with excellent tension is provided to enable oxide(containing Zr, REM and Ca) to be generated and to enable a steel member with appropriately controlled size and number of oxide. CONSTITUTION: A method of manufacturing a steel member with excellent tension comprises next steps. The steel member consists of C of 0.02~0.15mass%, Si of 0.5mass% or less, Mn of 2.5mass% or less, P of 0.03mass% or less, S of 0.02mass% or less, Al of 0.05mass% or less, Ti of 0.005~0.10mass%, Zr of 0.0005~0.050mass%, REM of 0.0003~0.015mass%, Ca of 0.0003~0.010mass%, N of 0.010mass% or less, O of 0.0005~0.010mass%, Fe and inevitable impurities. The dissolved oxygen of steel is controlled to be within a range of 0.0005~0.01mass% before Zr is added.