| 摘要 |
PROBLEM TO BE SOLVED: To provide steel for a bolt excellent in cold forgeability and sulfuric acid corrosion resistance. SOLUTION: For improving cold forgeability, the content of N is controlled to <=0.01%, one or >= two kinds among Al, Nb, V and Ti are added by suitable amounts and moreover, Ceq(=C+Si/24+Mn/6+Cu/15+Ni/15+Cr/5+Mo/5+V/5) is controlled to <=0.500%. For improving sulfuric acid corrosion resistance, the content of C is controlled to >0.15 to <0.30% and Cr, Cu and Si are added respectively by suitable amounts.
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