| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a steel sheet having low production cost, high productivity and excellent in brittle crack propagation arresting performance of a base material and toughness of a weld heat affected zone during high input heat welding.SOLUTION: A steel sheet has a predetermined chemical composition, carbon equivalent of 0.30 to 0.40 mass%, SOLB of -0.0015 to +0.0015 mass%, a weighted mean Dof particle diameter of crystal particles of 3.0 to 17.0μm at a sheet thickness 1/2 part, area percentage of a face {100} having an angle in 15° to a surface vertical to a rolling direction of 2.0 to 20.0% at the sheet thickness 1/2 part, total number density of TiN particles, MnS particles and composite particles each having 0.5 to 2.0μm circle equivalent diameter at a sheet thickness 1/4 part of 20 to 200/mm, number density of oxide particles having 1 to 10μm circle equivalent at the sheet thickness 1/4 part of 20 to 200/mm, sheet thickness of 10 to 35 mm and yield stress of 300 to 500 MPa.</p> |
