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).
Metallurgical treatments for steel, including cyanide baths for springs and steam oxidation for corrosion resistance.
| Identifier | ExFiles\Box 154\2\ scan0115 | |
| Date | 14th July 1938 | |
| - 2 - 14th. July 1938. Messrs. Thos. Firth & John Brown Ltd., Sheffield. 1. intelligent use of a cyanide bath. Personally, I have advocated this for at least five or six years, but as recently as last year the N.P.L. have investigated this matter and demonstrated that a plain straight coiled spring of large dimensions treated in a cyanide bath to recarburise the surface but otherwise as rolled, gave better results than similar springs, which were :- (a). Ground before winding. (b). Shot blasted. and it is therefore now abundantly evident that the scheme in question is sound, and it only requires intelligent effort to make it commercially practicable. With the object of overcoming corrosion attack, it is well known that oxides produced by high temperatures are much less prone to atmospheric attack than clean steel. Furthermore it is well known that today washing boilers are produced in pressed steel, and protected by a treatment which produces magnetic oxide of iron in a regular thickness over the face of the material. The method is quite effective, as in my own house I have a washing boiler of this type, which has been in service for 20 years and is still corrosion proof, and leaves no oxide stains upon linen or cotton. The question of protection by the production of magnetic oxide is a common process in connection with the manufacture of ordinary washing boilers. A general outline of the principle is that steel is oxidised in an atmosphere of steam at round about 700°C. It is held sufficiently long to produce a thin continuous coating. It is then transferred to another muffle, and held for a short time at 930°C to transform the mixed oxides formed by the steam into the stable magnetic oxide which is resistant to further corrosion attack. (a). Summarising the above, it means that a certain amount of experimental work should be possible to roll plates carefully to size, and in short lengths, to obtain a small and regular depth of decarburisation. (b). To recarburise such plates by a cyanide bath. This becomes practicable by dividing the depth of decarburisation by 5 and by proper furnace control, making this depth regular. | ||