Investigation into mysterious breakages of cadmium plated screws, identifying hydrogen embrittlement as the cause and proposing heat treatment as a remedy.
| Identifier | ExFiles\Box 30\6\ Scan060 | |
| Date | 9th November 1928 | |
| Sft {Mr Swift} RHC. {R. H. Coverley - Production Engineer} Mr. Fendlebury. Hs. {Lord Ernest Hives - Chair} Hs. {Lord Ernest Hives - Chair} Rg {Mr Rowledge} Hl X1360 BY16/G.9.11.28. CADMIUM PLATING. ------------- As a result of having one or two rather mysterious breakages on cadmium plated screws, I had a piece of bar produced screwed for its whole length, and then cut up into short lengths. The parts were then divided as follows :- (a) One set of parts were kept as produced. (b) The second set were cadmium plated. (c) We tested for bending all of the parts in question. The unplated screwed rod bent through 90° without fracture, the plated piece broke short at less than 50° bend. In view of this therefore and until we have found a remedy it is certain that screwed pieces of the nature of bolts or rods should not be protected by cadmium plating. We are trying out whether heating the parts to 150°C for an hour, which is a well known remedy for brittleness, resulting from occluded hydrogen, will entirely remove brittleness. At the same time we are investigating why this type of brittleness should be present when we were under the impression we were using an alkaline solution for plating. We would again emphasize the fact that acid baths must not be used for cleaning any parts intended for cadmium plating. We are afraid that possibly we shall find the screwed rods referred to may have been cleaned by pickling in acid. We are of the opinion that it will be necessary for us to introduce on all parts carrying stress, which are cadmium plated, a treatment at about 150°C. BY. {R.W. Bailey - Chief Engineer} | ||
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).