From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Nitrogen hardening treatment process for Firth's H.R. Crown valves.
| Identifier | ExFiles\Box 154a\1\ scan0178 | |
| Date | 29th November 1929 | |
| c.HS.{Lord Ernest Hives - Chair} c.WCR. X4469 BY/EM1/J.29.11.29. FIRTH'S H.R.CROWN VALVES. -------------------------- As we have pointed out to you, we are informed that it is possible to apply the nitrogen hardening treatment to the above material without infringing the nitralloy patents, and that good results have been obtained on this and similar materials by the application of this process to valve stems. We are handing you herewith two H.R.Crown Steel Valves which we shall be glad if you will have treated, and let us have your report upon same in due course. We are informed that it is necessary to treat these parts by exposing them to the ammonia gas for ten hours at a temperature of 550 to 600°C. BY/EM. | ||