| 摘要 |
1418310 Heat-treating carburized steel USS ENGS &ÀCONSULTANTS Inc 22 Dec 1972 [3 Jan 1972] 59434/72 Headings C7A and C7U. Steel containing not more than 0.4% C is carburized at a temperature above 1700‹C to produce a maximum in the case of 0.8-1.2%C, after which it is quenched to below M s of the case, and reheated into the bainite region to transform all residual austenite. It is then heated into the temperature range of A3 (of the core) - (A3 + 100‹F), held only for sufficient time to permit temperature equalization throughout the crosssection and quenched to produce a martensitic case. In a modification the steel is quenched directly from the carburizing temperature into the bainite region, while in either process a final tempering step may be carried out conventionally e.g. 1 hour at 400‹F. The process is particulalry applied to gears, bearing races and bushings. |
