Highly corrosion resistant Ni-Cr-Mo steel excellent in weldability and surface properties and method for producing the same

摘要

PROBLEM TO BE SOLVED: To provide a Ni-Cr-Mo steel having excellent corrosion resistance, weldability and surface properties. SOLUTION: C: 0.005-0.035%, Si: 0.02-0.25%, Mn: 0.03-0.40%, P: ≤ 0.030%, S: 0.0001. -0.0020%, Ni: 32.0-38.0%, Cr: 21.0-25.0%, Mo: 6.0-8.0%, W: 0.01-2.0%, Cu: 2.0 to 5.0%, N: 0.18 to 0.30%, B ≤ 0.0005%, Ca ≤ 0.0015%, REM ≤ 0.0020%, Al: 0.005 to 0 .150%, Ti: 0.002 to 0.200%, O≦35 ppm, the balance being Fe and unavoidable impurities, and Ni—Cr—Mo steel satisfying the following formulas (1) to (3). 1.3*Mo+1.0*W-1.3*Cu-52.7*Al-17.9*Ti<6.5... Formula (1), 8.4*Si+Cu<4.70... Formula (2 ), Ti+0.625×Si<0.26... Formula (3) [Selection diagram] Figure 1