| 摘要 |
PURPOSE:To obtain the titled parts having a good workability and capable of obtaining the required parts strength, by heating steel having a prescribed compsn., then hot rolling it in as held state in the heating temp. range, heating and casting only the part to be formed of member obtd. by cooling and cold finishing to a prescribed shape, then high frequency quenching it. CONSTITUTION:Steel contg. by weight 0.30-0.65% C, 0.10-1.50% Si, 0.20-2.0% Mn, 0.005-0.030% N and 0.03-0.50% V is heated to >=1,050 deg.C to sufficiently enter V carbonitride into solid soln. in austenite. Next, steel after heating is hot rolled to a prescribed dimension in as held state to the temp. range, next, the rolled material is cooled in temp. range to Ar1 transformation point by >=1 deg.C/sec rate. Then only the part to be formed such as gear tooth is heated to <1,050 deg.C by e.g. high frequency heating in the rolled and cooled material, and formed to the described tooth shape by forging (form rolling) to obtain the aimed titled parts.
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