Specularity and machinability to the excellent plastic mold steel

摘要

PROBLEM TO BE SOLVED: To provide a steel for metal mold for plastic molding, excellent in mirror-finish characteristics as well as machinability such as rendering of long cutting tool life and high machining efficiency. ;SOLUTION: A steel has a composition containing, by weight, 0.05-0.20% C, ≤1.0% Si, 0.5-2.5% Mn, 2.5-3.5% Ni, 0.5-2.5% Cu, and 0.5-1.5% Al as principal alloy components, also containing ≤15 ppm 0 and ≤150 ppm N, and having the balance Fe with inevitable impurities. Moreover, the size of non-metallic inclusions except sulfide contents is ≤50 μm when estimated by the extreme value statistical method (ROOT AREA max). This steel is excellent in machinability as well as mirror-finish characteristics as shown in a graph in the figure.;COPYRIGHT: (C)1999,JPO