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 properties of a nickel-chromium alloy named Nichromic.
| Identifier | WestWitteringFiles\V\December1930-February1931\ Scan062 | |
| Date | 23th December 1930 guessed | |
| COPY. "N I C H R O M I C" Alloys having nickel and chromium as their basis have now been known a long time, but have only come into general use for industrial purposes during the last few years, owing to certain remarkable properties peculiar to them, viz: (a) - Retention of their hardness in a hot state; (b) - Their resistance to oxidation, etc...... Whilst a considerable amount of work has been done in foreign countries with the object of bringing these alloys to perfection, our metallurgists have likewise not failed to study them with the result that their operations have enabled us to improve upon "Nickel-Chromium" alloys and ultimately discover "NICHROMIC" which we are now producing in a general way and which has forthwith been adopted in a great many large engineering works, etc..... SOME OF THE PRINCIPAL PROPERTIES OF NICHROMIC. NICHROMIC, whilst possessing a resistance to tensile strain comparable to that of extra mild steel, retains such resistance up to a very high temperature, thus enabling castings made of this alloy to be easily manipulated in a very hot state. At such temperatures, it is not brittle, and can even be rapidly cooled without danger. (a) - Retention of hardness in a hot state. - Mr. Leon Guillet states in one of his articles: "For retaining their hardness at high temperatures, the nickel-chromium alloys are most remarkable, being followed by manganese-steel, cast iron, and chromium tungsten steels ......”. The study of the variation of hardness, made by this learned metallurgist and verified by ourselves in every particular, enables us to state that, even after several excessive reheatings, this characteristic varies little up to 850°C. Brinell's number remains constantly in the neighbourhood of 200, even in the case of cast alloys, whilst in ranges from 85 (for ordinary temperature) to 22 in the case of extra-mild rough steel forgings, under the same testing conditions. contd. | ||