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 discussing the properties and suitability of various steel types for components like turbine blading, brake levers, and valves.
| Identifier | ExFiles\Box 75\5\ scan0007 | |
| Date | 4th March 1919 guessed | |
| - 2 - Such a type of steel cannot be hardened, and as stated in their letter, it is difficult to machine. I do not in any way recommend it for the purpose in question as one does not like to think of using a steel in a severely cold worked condition for such an important part, as it is bound to have considerable internal stresses left in it by this operation, and from our own experience this steel when cold worked is impossible to machine. some considerable time ago the Turbine Builders in this country tried, with very disastrous results, 25% nickel for their Turbine Blading, and this after running in the Turbine for some short time for some unknown reason failed. As to whether this would occur with the above mentioned chemical properties, I naturally cannot express any definite opinion. One does not like to think of any risk being run in such important parts as brake levers, which themselves get a distinct amount of vibration from the road, and I would strongly recommend them to adopt our standard F.G. Stainless steel heat treated to give the following mechanical properties;- Yield Point.......... 30 tons per sq.in. Ultimate Stress...... 40 to 50 tons " Elongation........... 25 per cent. This steel is far more readily machinable, and if they do require hard surfaces for wearing, it can be hardened, and tempered if necessary to give tonnages in the neighborhood of 100 tons, to say nothing of the fact that it is considerably cheaper than the steel suggested. With reference to the adoption of Silchrome in place of "Quickstep" for valves, if they are not satisfied with the life they obtain from their present steels, I would suggest to them also trying a 14% Chrome with a high Carbon content, viz., in the nature of .70 to .80% or even higher as this has proved in certain air cooled engines to give extremely good results. Yours truly, (Sgd) J.W. Fawcett. | ||