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).
Letter from Wellworthy Piston Rings Ltd. discussing the composition and performance of different valve seats.
| Identifier | ExFiles\Box 115\5\ scan0049 | |
| Date | 30th May 1938 guessed | |
| 3 Phosphorus ........ Max. .70 Manganese ........ .50- 1.0 Chromium ......... .80 -1.1 Molybdenum ....... .80 -1.1 but whereas the Thompson "Durachrome" Valve Seat is cast in the hardened condition, Lymalloy is cast in a completely machineable state, and is hardened and tempered either by air-hardening or may be quenched in oil, and then re-tempered, and seats produced by either method have definitely proved in service to be superior to the Thompson "Durachrome", as they did not crack or chip in service and generally speaking leave a better condition of the actual seat on the valve itself, whereas with the Thompson Durachrome and one or two other hardened seats of High Chromium Iron produced in this country such has not been the case. Mr. Knight mentioned to you that we should be pleased to quote you for any requirements in this direction and we are able to assure you that the length of life of these seats is between 65 and 70% of that of the Stellited Seat. Assuring you of our fullest co-operation and service at all times, We are, Yours faithfully, For WELLWORTHY PISTON RINGS LTD., Technical Manager. | ||