| 摘要 |
A light gauge (typically 0.25 mm to 0.50 mm) ferritic stainless steel containing, for example 1.2% titanium, is nitrided in ammonia at a temperature between 816 DEG C and 982 DEG C, for a period of, typically, 25 minutes, converting all the uncombined titanium to dispersed particles of titanium nitride. At the same time, chromium in the steel is converted to chromium nitride, but this is then decomposed by a denitriding treatment carried out in hydrogen at about 1100 DEG C for 3 hours. The resulting steel contains a dispersion of titanium nitride particles with an interparticle spacing of, preferably, less than 2 microns.
<??>In an alternative treatment, the nitriding step is not continued for long enough to convert all the titanium to titanium nitride, but the chromium nitride is then decomposed in an annealing step at below about 980 DEG C, rather than a denitriding step; the nitrogen released from the chromium nitride combines with the remaining titanium to form titanium nitride. |
