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).
Laboratory report on the unsatisfactory heat-treatment of a batch of steering rollers due to an abnormal case depth requirement.
| Identifier | ExFiles\Box 153\1\ scan0267 | |
| Date | 19th April 1939 | |
| 1300. F.J. HARDY. Laboratory. 19/4/39. Hmr. Ry. Fm. Phe. F.J.H. Steering Roller - EW 905. A batch of approximately 100 of the above pieces were produced here between April 3rd and April 7th. The drawing requirements for this piece calls for an abnormal depth of case i.e. .060"-.070". To obtain this it is necessary to carburize for 16 hours at 880/890C, which is a longer period even than we give to such parts as aero reduction gears. Soaking under these conditions produced a very high saturation of carbon near the surface or outside layers of the parts treated. Heat-treatment after carburizing must be controlled so that both the carburized case and the core are well refined. This means that the times and temperatures used should be sufficient to bring the saturated carbon due to carburizing into "solution", and the subsequent quenching holding it in that condition. From our experience with this material together with information given to us by Messrs Hoffman's representatives this batch of rollers was heat-treated giving the normal temperatures for this steel. Unfortunately owing entirely to the unusual depth of carburizing these conditions were found to be unsuitable to properly refine the case. It was found by fracture test that the outer layers were very coarse, and in this condition the case was very unsatisfactory for use. | ||