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).
Comparison of properties and structures between chrome vanadium and American plain carbon steel springs.
| Identifier | ExFiles\Box 88\4\ scan0056 | |
| Date | 3rd May 1934 guessed | |
| -2- One of these was put through all the tests applied to the chrome vanadium steel springs, with equally good results. It was particularly noticed that the hardness was the same (429 Brinell) and that Brinell figures obtained from tests made on the Vickers machine with a light load and small ball on the outside of the wire, were the same as the figures obtained at the centre. The manganese content of the wire was determined in the course of identity tests, and found to be 0.59%. Two photomicrographs are sent herewith. No. A1,077, X150. Broken Chrome Vanadium Steel Spring. No. A1,078, X150. American made plain carbon Steel Spring. These are of transverse sections of the springs and illustrate the difference in the structure of the two types of wire. We have compared the structure of the American wire with that of samples of J.{Mr Johnson W.M.} Shipman's and Brunton's piano wires, and find that the American wire is quite free from decarburisation, whereas both of the English wires showed a little surface decarburisation, (See photomicrographs Nos. A755-4 - Report M770 - 19.2.32. also No. A703 - Report M738 - 12.3.31). The structures were otherwise practically identical. The American springs had a decidedly rougher surface than the broken chrome vanadium steel springs, but there were no pits or transverse cuts, all the marks being of a longitudinal character. For your information we have asked the Inspection department to measure one of the springs, which happened to be broken in one place only; and also two of the American Springs. The figures obtained are given below with the drawing requirements. Drawing Requirements:- Small end bore - 0.975" +10 Large end bore - 1.100" +10 True length - 1.940" Poundage when compressed to 1.450" - 56lbs. ± 14 ozs. contd. | ||