| 摘要 |
<p>A hot-rolled shape steel for ships which is manufactured by heating a bloom containing by mass C: 0.03 to 0.25%, Si: 0.05 to 0.50%, Mn: 0.1 to 2.0%, P: 0.025% or below, S: 0.01% or below, Al: 0.005 to 0.10%, W: 0.01 to 1.0%, Cr: 0.01 to less than 0.20%, and N: 0.001 to 0.008% to a temperature of 1000 to 1350°C, subjecting the resulting bloom to hot rolling wherein the cumulative rolling reduction at Aror below is 10 to 80% and the rolling finishing temperature is (Ar-30°C) to (Ar-180°C), and then cooling the rolled steel by allowing it to stand and which has a microstructure composed of both ferrite containing worked ferrite and pearlite. Thus, a hot-rolled shape steel for ships which exhibits excellent corrosion resistance even when used in a severe corrosive atmosphere accompanied with corrosion due to seawater, e.g., ballast tanks of ships and which has strength corresponding to YP of 315MPa or above and is usable as longitudinal (lounge) or the like can be provided at a low cost.</p> |
