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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).
Letter to a bearing company detailing heat treatment instructions and proposing a change in steel specification for rollers.

Identifier  ExFiles\Box 153\2\  scan0161
Date  4th November 1936
  
- 2 - 4th. November 1936.

Messrs. Ransome & Marles Bearing Co. Ltd.,
Newark on Trent.


First Quench - From 850°C.
Second Quench - 760°C.
Oil Temper two hours at 125°C.

In this connection we are certain that the brinell will not be materially altered by the oil tempering for 2 hours at 125°C. In our experience 140°C at two hours is the critical point at which a steel of this nature begins to soften its case. In any case we will take responsibility for the condition of the rollers as delivered, on the understanding that you follow these instructions.

In our own view we would prefer to use steel to the Air Ministry specification S.82, which has the following composition

Nickel 4.00 to 4.50 %
Chromium 1.00 to 1.20 %
Carbon Not to exceed .16

This is a steel we have considerable experience with, and we propose to supply some of this bar material to you in the near future in order that you may make some sample rollers, which will then be tried out by Experimental Department. Personally, I have no fear of the results, but it will be necessary for us to make some tests to justify the change. Using this steel the heat treatment temperatures are as follows :-

(a). Carburise at 890° for four hours to obtain the necessary depth of case.

(b). First Quench - core condition, between 840 to 850°C.

(c). Second Quench - for case, 760°C.

(d). Temper in oil at 125°C for two hours.

We have some nickel chrome case hardened steel to S.82, on order in bar to the required size to make the rollers, and we will send a sample of this to you as soon as it is available. In the meantime we would suggest that you merely meet our requirements from the material supplied by Adamants, so that if we are in the position to quickly make a change we can return the material to the Adamant Co, who have a use for it in other directions.

Yours faithfully,

FOR ROLLS-ROYCE LIMITED.

TECHNICAL PRODUCTION ENGINEER
  
  


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