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).
Analysis of 'picking up' and pitting issues on S.S. exhaust valves and seatings, attributing the problem to the softness of the Aluminium Bronze used.
| Identifier | ExFiles\Box 148\3\ scan0061 | |
| Date | 16th July 1929 | |
| Hs{Lord Ernest Hives - Chair}/AJL. X1476. Hll/EA16.7.29. Laboratory. XY/230. X1476. S.S. Exhaust Valves and Seatings. There has been trouble recently due to "picking up" of Aluminium Bronze from the seating, which has resulted in serious pitting. An analysis and examination of some of the valves does not indicate anything exceptional. The Aluminium Bronze used for seatings is, I consider, on the soft side, namely about, 105 Brinell in the cold. (much of the Aluminium Bronze used in the past for this purpose has been about 145 Brinell). I do not know the temperature it would attain under rather hot conditions, but conclude it would be as much as 500°C locally, at which temperature it has a hardness of about 90 Brinell, falling off rapidly with slight further increase in temperature. The "picking up" would be less liable to occur if the Aluminium Bronze had a composition which would give a somewhat higher Brinell. Hl. HE | ||