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).
Micro-examination report on a failed lever from a Phantom III front suspension unit, investigating incorrect heat-treatment.
| Identifier | ExFiles\Box 95\3\ scan0178 | |
| Date | 28th November 1935 | |
| Micro-Examination Report. M1087. To Hs.{Lord Ernest Hives - Chair} from Hl. c. BY.{R.W. Bailey - Chief Engineer} c. Da.{Bernard Day - Chassis Design} c. Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} HL4/AG.28.11.35. Laboratory. LEVER, G.81431, FROM FRONT SUSPENSION UNIT, OFF PHANTOM III. N.S.F. The above lever broke after running 499 hours. As in the previous case, fatigue cracks had developed at the base of the splines (See previous report M.1070). The Brinell hardness, 272, was correct to the rather low range quoted by the drawing at the time of the previous investigations. The fracture, however, was unusual, so the part was fractured again, when it was found to be in coarsely crystalline and very brittle condition. See fracture "A" in photomicrograph NO. A1,333, X3. The forging had evidently not been heat-treated. After giving the correct heat-treatment, including normalising, to yield the same Brinell, the fracture "B" was obtained, indicating a tough fibrous material with good ductility. Further evidence of the state of the material is afforded by photomicrographs Nos. A1,334, and A1,335, X100, which show respectively the structures of "A" and "B". The remainder of the part together with two fracture samples are returned herewith to Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} Hl. Photomicrographs Nos. A1,333/4/5 att. | ||