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).
Heat treatment and hardness testing of various pistons.
| Identifier | ExFiles\Box 66\1\ scan0173 | |
| Date | 11th May 1928 | |
| X8040 c. Hs.{Lord Ernest Hives - Chair} BY8/G.11.5.28. PISTONS. --------- In connection with the question of heat treating pistons, the question naturally arises as to whether the figures obtained by the ageing treatment (or equivalent low temperature) will be maintained under the running conditions of the engine. The pistons in our Phantom reach a temperature of 220°C. I would therefore like to try out some of the standard pistons which we can harden by a low temperature treatment and see whether the brinell figure obtained persists if we maintain the piston at a temperature of say 230° for approximately 100 hours. In this connection I propose also to send you an American piston which must have been artificially hardened, to give it a similar test, as it is most important to ascertain whether the heat treatment given to the pistons will be permanent under running conditions. In the case of the aero engines, the temperature will be higher, but I believe you have figures from Hs.{Lord Ernest Hives - Chair} which cover this particular point. In any case you should check the heat treated pistons in your latest alloy after Hs.{Lord Ernest Hives - Chair} has given them a lengthy period of running. In the case of 'Y' metal, Booths do not give a low temperature treatment, they depend on the normal hardness arrived at by the quench, and of course the big point in the 'Y' metal is the relative maintenance of its strength at high temperatures. I appreciate that the annealing temperature is higher than the figure quoted above; but in a number of experiments on various alloys it was demonstrated that a long period at a temperature just below the annealing temperature would definitely soften the piston and practically bring it back to its quench condition so far as brinell hardness is concerned. BY.{R.W. Bailey - Chief Engineer} | ||