Patent ID: 6869489
Filing Date: 2005-03-22
Classification: C21D,C22C,F16H

Abstract:
1. A steel for a high bearing pressure-resistant member, having a high machinability, said steel being formed of a machine structural steel comprising carbon in an amount ranging from 0.15 to 0.25% by weighs, silicon in an amount of not less than 0.4% by weight and not more than 1.23% by weight, nickel in an amount ranging from 1 to 3% by weight, chromium in an amount ranging from 1.2 to 3.2% by weight, and molybdenum in an amount ranging from 0.25 to 2.0% by weight, a total amount of chromium and molybdenum amounting to at least 2.71% by weight, said machine structural steel containing carbide precipitated under a heat treatment or spheroidizing, the carbide having an average particle size of not larger than 1 μm and the maximum particle size of not larger than 3 μm, wherein said heat treatment includes maintaining said machine structural steel at a temperature ranging from 700 to 820° C., and cooling said machine structural steel to a temperature of 600° C. at a cooling rate of not higher than 20° C. per one hour.