| 摘要 |
PROBLEM TO BE SOLVED: To provide a micro-alloying steel product for hot working which is prepared by only forming steel excellent in machinability into a part shape by hot working and machining and has an abrasion resistance as high as that given by a surface hardening treatment. SOLUTION: This micro-alloying steel product comprises 0.40-0.60 mass% C, 0.05-0.80 mass% Si, 0.8-2.0 mass% Mn, 0.04-0.3 mass% S, 0.5-2.0 mass% Cr, 0.03-0.5 mass% V, 0-0.02 mass% Ca, 0-0.050 mass% Al, 0-0.025 mass% N, and the balance being Fe and impurities. The structure of the steel product within the region from the surface layer to the depth of 200 nm is a mixed structure comprising proeutectoid ferrite in an areal ratio of 5% or less and pearlite with a lamellar distance of 30 nm or less. COPYRIGHT: (C)2004,JPO
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