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 Nitralloy steel samples removed from a nitriding furnace.
| Identifier | ExFiles\Box 154a\1\ scan0195 | |
| Date | 30th January 1930 | |
| MICRO-EXAMINATION REPORT. x+469. M683. BY.{R.W. Bailey - Chief Engineer} c to Sft{Mr Swift}/Mr. Pendlebury. c to Hs.{Lord Ernest Hives - Chair} Hll/30.1.30. Laboratory. RE. NITRALLOY STEEL. As requested we have examined samples representing a charge of the above material removed from the nitriding furnace on the 27th. inst., after 80 hours treatment as recommended by Mr. Mannock. These consisted of two small spindles, one of which showed a black stain on the outer surface, surrounding an oil-hole. The other spindle was coloured brown on the side which had been in contact with the floor of the retort. Micro-sections were made which included these marks. In neither specimen was any difference found between the case on the stained side and that on the other side. An attempt was made to preserve the brittle surface of the micro-specimens by nickel-plating, but this was not successful. We cannot therefore give the exact depth of case. The actual measurement obtained was 0.022". This figure was confirmed by measurements of fractures. Inclusion of the outer layer would probably bring the figure up to 0.025". It will be understood, of course, that the above figures refer to the case actually visible on the fracture or the etched micro-section. As far as we can judge from the results of file tests, there is no appreciable hardening below this visible case. The structure of the case was found to be similar to those previously examined. Below the outer layer there is the region containing the white constituent in the form shown in our previous photomicrograph No. A605. The core contained a large number of small and brittle slag oxide particles which we understand from Mr. Mannock, is unavoidable in this type of material. Hl. He | ||