| 摘要 |
PURPOSE:To maintain excellent machinability even at a hardness of HRC43 or above, by providing a low C - medium - low Mn - Ni - high Cu - high Al - S steel having a specific composition. CONSTITUTION:This steel for metal mold has a composition consisting of 0.08-0.17% C, <=0.60% Si, 0.50-1.20% Mn, 2.50-3.50% Ni, 0.85-1.50% Al, 1.80-2.50% Cu, 0.05-0.16% S, and the balance Fe. Moreover, either or both of Mo and W, independently or in combination satisfying 1/2W+Mo=0.10-0.70%, and/or <=0.50% Cr may further be added to the above steel, if necessary. This steel is provided in a prehatdened state (tempering at >=400 deg.C, generally, after hardening) of >=HRC37 hardness and used after subjected to die sinking and grinding finish in this state. This steel maintains superior machinability even at a hardness of HRC43 or above.
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