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).
Technical report providing an analysis and comparison of three American Silcrome valve steels.
| Identifier | ExFiles\Box 158\4\ scan0212 | |
| Date | 12th February 1938 | |
| See Peller 1360 Rm{William Robotham - Chief Engineer} To Rm.{William Robotham - Chief Engineer} from HPS.{Horace Percy Smith - Experimental Factory Mgr} Please return to HPS.{Horace Percy Smith - Experimental Factory Mgr}1/VS.{J. Vickers}12.2.38 VALVE STEELS. We give herewith certain information which has been passed on to us in regard to the latest American Silcrome valve steels. 1. ANALYSES. SILCROME SILCROME SILCROME XCR. XB. X-8. Carbon .40 - .50 .60 - .86 .20 - .25 Phosphorous .035 Max. .025 Max. Sulphur .035 Max. .025 Max. Manganese 1.00 Max. .20 - .60 1.20 - 1.50 Silicon 1.00 Max. 1.25 - 2.75 3.70 - 3.90 Chromium 23.25 - 24.25 19.00 - 23.00 20.50 - 22.00 Nickel 4.50 - 5.00 1.00 - 2.00 10.50 - 12.00 Molybdenum 2.50 - 3.00 1a.RELATIVE MERITS. Silcrome XCR. is the best steel. It can be hardened, is highly corrosion resistant to leaded fuel and has high hot strength and a hard seat, although the oxidation resistance is not as good as we should like. The steel is really austenitic in analysis, yet it can be hardened. It must be forged within a very close temperature range. On comparative tests it has proven the best of the valve materials for automotive work. Silcrome XB is an improvement over No. 1 Silcrome. It has higher hot strength and better corrosion resistance. The steel is not as good as XCR, but it is in general superior to Silcrome No. 1. With both XCR and XB we have had some tendency for the valve to dish under severe operating conditions. Silcrome X-8 is an austenitic steel with good hot strength, but it can not be hardened and has a high coefficient of expansion. It is very good from a corrosion standpoint. The seat is soft, and much more inclined to pitting than either of the other steels. continued. | ||