| 摘要 |
PURPOSE:To make the soft nitriding treatment possible at a lower temperature and in a shorter time than the usual method, by treating the steel in the atmosphere contg. a fixed volume of wet HCl gas in NH3 gas and promoting the formation of nitrogen compound. CONSTITUTION:Steel is treated in the atmosphere contg. 5ppm-5vol% wet hydrogen chloride gas in ammonia gas. The decomposition of ammonia gas is remarkably promoted by adding wet hydrogen chloride gas and nitriding concentration in said atmosphere is increased and then, soft nitriding treatment is made easy by advantageous treating conditions i.e. lower temperature and shorter time. The surface of the steel to be treated is more hardened, and the fatigue resistance and abrasion resistance are remakably improved by performing preliminarily the soft nitriding treatment of this invention after giving the residual stress on the surfade layer of the steel by the mechanical means, for example, shot peening etc. |
