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 nitriding treatment of austenitic steel liners.
| Identifier | ExFiles\Box 154a\1\ scan0264 | |
| Date | 22th June 1932 | |
| c. RHC{R. H. Coverley - Production Engineer} c. RG{Mr Rowledge} c. HS{Lord Ernest Hives - Chair} c. Sft{Mr Swift} 84469. c. Sft{Mr Swift}/Mr. Pendlebury. BY/EM2/O.22.6.32. Nitriding Treatment of Austenitic Steel Liners. Following upon RHC{R. H. Coverley - Production Engineer}'s report regarding the failure to obtain satisfactory results with the austenitic liners which we have been trying to harden, we have made further enquiries from various sources where we have reason to believe that the nitriding treatment of austenitic materials has been carried out successfully and we find that the following represents what can be accomplished in this direction. (1) Using KE.965 Steel, the thickness of case obtained with a 48 hours treatment is .003" and the hardness of same is 800 to 1000 brinell. (2) It is essential to copper deposit the liners where they are desired to be hard. (3) No matter what precautions are taken it seems impossible to entirely avoid distortion on such parts as cylinder liners and the general practice in this connection is to completely finish the bore of the liner and then nitride and if the amount of distortion is small, no attempt is made to correct it, but if the amount of distortion is considered excessive, then the usual practice is to put the liners into split wooden clamps and by careful bolting up to stretch them back again to correct form. (4) It is found that the best temperature for nitriding is 600°C. for a period of 48 hours and a back pressure of 4" of water is found to be essential to keep the nitriding box full of ammonia. The rate of dissociation of the gas is considered to be about 30% although it is stated that anything between 20% and 70% is considered satisfactory. In view of the fact that we still have a contract outstanding for a set of Kestrel Engine liners in austenitic steel, we suggest that we attempt to do these along the lines suggested above. BY/[Signature] | ||