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 Phantom III front spring, detailing its material analysis and hardness tests.
| Identifier | ExFiles\Box 95\3\ scan0182 | |
| Date | 7th December 1935 | |
| 4346 Micro-Examination Report. M1091. To Dr. R- (Struck through) Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} HL2/AG.7.12.35. Laboratory. PHANTOM III FRONT SPRING G.83271. The Salter's spring which you handed to us for examination has proved to be, not high carbon steel as you thought, but silico-manganese steel. Analysis: Carbon 0.50% Manganese 0.91% Silicon 2.02% These figures conform to our Specification 402. The spring was labelled "143 hours Bumper Test - 13.9.35", but we understand that this test was made with 2" Cams whereas the test on the Firth's chrome vanadium steel spring was made with 3" cams. The attached photomicrographs Nos. A1,341 and A1,342, X150, show respectively the edge and interior of a transverse section of the spring. There is a slight difference between these. That this is probably due to slight surface decarburisation is borne out by the hardness figures, which indicate a surface rather softer that the centre. Hardness Tests. Centre. Surface. V.P.N./30 Kg. 557 550 V.P.N./10 Kg. 566 548 Brinell 2/120 521 508 Brinell 2/120 536 518 - Vickers m/c. These figures are of course higher than we specify for springs. Hl. HC Fracture samples and photomicrographs No.s. A1,341/2 att. | ||