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 Phantom III front coil spring, investigating surface decarburisation.
| Identifier | ExFiles\Box 95\3\ scan0169 | |
| Date | 22th November 1935 | |
| 346P III Front Suspension KFS Micro-Examination Report. M1083. To HY.{Tom Haldenby - Plant Engineer} B. Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} HL1/AG.22.11.35. Laboratory. Re: Phantom 111 - Front Springs. (Your ref: BY/EM3/C.18.11.35) We have been unable to confirm the suggestion put forward in your memo., that the failure of the broken coil spring was due to surface decarburisation. Photomicrograph No. A1,328, X150, shows a transverse section of the spring, in which the irregularities of the surface have been preserved by a nickel coat. You will note that there is no indication whatever of decarburisation, even at the extreme edge. This was confirmed by examination of the curved surface. A series of hardness tests was carefully made and checked. For this purpose a specimen was carefully polished on the round surface; only just sufficient metal being removed to enable us to obtain a finish adequate for Vickers tests. The section was also polished on the side to enable tests to be made in the centre of the rod. Hardness Tests. Centre. Surface. Brinell (120 Kg/2 mm.) 444 444 V.P.N - (50 Kg.) 485 - " - (30 Kg.) 484 481/487 " (10 Kg.) 473/473 483 These figures show correct and uniform hardness, which together with the fine-grained structure confirms the heat-treatment the spring has received. We understand that the raised "lip", at the edge of the fractured surface, is partly responsible for the suggestion of surface decarburisation. contd. | ||