| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot-rolled steel sheet which is optimum for use, e.g., to the stock for a compressor shell having satisfactory low temperature toughness after deep drawing, and to provide a method for producing the same. SOLUTION: The hot-rolled steel sheet has a composition comprising 0.0005 to 0.0040% C,≤0.1% Si,≤0.14% Mn,≤0.025% P,≤0.008% S, 0.003 to 0.1% Al, 0.0005 to 0.0060% N, 0.021 to 0.08% Ti and 0.0021 to 0.0050% B, and in which the relation among S, N and Ti satisfies the following relationship (1), and the balance Fe with impurities. The ferrite crystal grain size number prescribed in JIS G 0552 is≥5.5. The ratio of A based inclusions obtained by a point counting method prescribed in JIS G 0555 is≤0.015%. The ductile-brittle transition temperature after cupping at a contraction ratio of 2.0 is≤-70°C. The tensile strength at a room temperature is≤340 MPa. The maximum nominal stress at 700°C is≥50 MPa. The steel sheet can comprise suitable amounts of one or more kinds of metals selected from Cr, Mo, Ni, Nb and V: Ti≥(48×S/32)+(48×N/14) (1). COPYRIGHT: (C)2004,JPO
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