Rolls-Royce Archives
         « Prev  Box Series  Next »        

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).
Micro-examination report on the nitrogen case-hardening of steel.

Identifier  ExFiles\Box 154a\1\  scan0131
Date  8th January 1929
  
MICRO-EXAMINATION REPORT.

VU469 M637.

BY.{R.W. Bailey - Chief Engineer}
c to R.{Sir Henry Royce}
c " Wor.{Arthur Wormald - General Works Manager}
c " Rg.{Mr Rowledge}
c " Hs.{Lord Ernest Hives - Chair}

Hll/EJW.8.1.29. Laboratory.

RE. NITROGEN CASE-HARDENING OF STEEL.
(Further to our memos. M626/9/35.)

Further tests on the half cylinder liner from Messrs. Hispano-Suiza have been carried out.

We find that after subjecting sections of the core to 24 hours treatment in our case-hardening nitrogen apparatus in the laboratory, at a temperature of 500 ± 5°C., the resulting case was similar to the original case found on the liner except that it had a brittle outer layer and was not quite so deep. The difference in depth is of course simply due to our treatment not having been continued quite so long as the original treatment.

The brittle outer layer, about 0.002" deep, had a similar structure, and the same tendency to flake off under shock, though not to anything like the same degree, as that on the test-pieces submitted by Messrs. Firth-Derihon. See report M626.

It is now evident that with regard to the formation of the brittle surface layer, the material used for the liner behaves during the case-hardening process in the same way as the material used for the original test bars and that the good behaviour of the liner's surface under shock is due simply to the removal of this layer by grinding or lapping. You will find, if you refer to our report M626, that our previous tests showed that the removal of the brittle surface exposed a surface which was free from the tendency to spall. In the same report we also noted that if the brittle layer was left on, the cracks resulting from shock tests tended to pass into the lower layers of the case.

Up to the present we have been unable to find any method of producing a nitrogen case without this type of surface. In our further tests we propose to investigate the effect of varying the period of nitration, and also the effect of rising and falling temperature gradients, using both the Firth-Derihon material, and the core of the Hispano-Suiza liner.

Hl. HE
  
  


Copyright Sustain 2025, All Rights Reserved.    whatever is rightly done, however humble, is noble
An unhandled error has occurred. Reload 🗙