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).
Laboratory report on hardness tests conducted on a burnt exhaust valve from a 20 HP, Chassis GAK-40.
| Identifier | ExFiles\Box 48\4\ Scan139 | |
| Date | 12th August 1924 | |
| 4226 HP. c. By.{R.W. Bailey - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} c. Wor.{Arthur Wormald - General Works Manager} H12/FW.12.8.24. Laboratory. Re. 20 HP. Chassis Burnt Exhaust Valve (from Chassis GAK-40). As requested by By we have made a series of hardness tests on a section cut from the head of this valve. The results are shown in the attached chart. It will be noted that there is no part harder than 286 Brinell. This indicates that the rate of cooling has been slower than in previous cases or that the valve has been hard but has subsequently been tempered by re-heating to a temperature below the critical range. The hardness figures are confirmed by the micro-structure. H1. he | ||