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).
The re-testing of cadmium plated small screwed parts to determine the angle of breakdown and check for embrittlement.
Identifier | ExFiles\Box 30\6\ Scan070 | |
Date | 20th December 1928 | |
By c to Hs.{Lord Ernest Hives - Chair} X 1360 M633. H11/EA20.12.28. Laboratory. Re Cadmium Plating of Small Screwed Parts. Your Ref BY5/G.19.12.28. Of the two samples which you sent to us, the one in the plated condition was broken completely, and the other almost completely. We have therefore retested the two samples, which we return herewith, in order to determine the angle of breakdown. The method of bending was the same as that finally adopted for the tests quoted in our memo. M631. i.e. the pieces were bent simultaneously and at the same rate, until a crack appeared that was just visible under a strong magnifying lens. The employment of this method was, we found, essential to the production of reliable tests. You will note that both of these specimens, when tested in this manner, broke down at the same angle, namely, 37 degrees. This bears out our remarks in our previous reports. It would seem, therefore, that, as in the case of the previous tests the plating operations have had no embrittling effect. The breakdown angle of these specimens is, you will observe, within a degree of several of the angles quoted in Table 2 of our report M631. As pointed out in our last report M632, we agree that the heat-treatment should certainly be used for the present as a precautionary measure, particularly as the Air Ministry has apparently decided that it is necessary. At the same time, the question of resistance to corrosion, if important in connection with small screwed parts, should be considered. Our note M632 was perhaps not quite clear to you, as therein we asked for samples of the original parts which failed on the engine, not for test bars. If you have any of the original parts available, we should be very interested to test these, when perhaps, we might find some peculiarity of material such as you believe to exist. Hl. H | ||