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).
Analysis and manufacturing process of a Nitralloy steel cylinder liner.
| Identifier | ExFiles\Box 154a\1\ scan0132 | |
| Date | 9th January 1929 | |
| HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Y4469 BY10/G.9.1.29. NITRALLOY STEELS. Re H11/EJW8.1.29. and HS{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}4/LG.8.1.29. In regard to the cylinder liner received from France it is evident it is an old piece by the analysis. None of the comparatively recently produced casts of this material, whether produced in France or England, contain nickel; in all the later steel for nitrogen hardening Molybdenum replaces nickel. Since it is an older piece it is still doubtful as to why the cylinder bore was ground. It could be ground for either of two reasons :- A/- As suggested by Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} to remove hard skin which may be assumed to be relatively brittle and likely therefore to crack when in a thin section, liable as a cylinder is to deformation. or B/- because they could not then produce so light a part accurately without grinding. In order to ascertain for which of the reasons the cylinder bore was ground, as grinding is exceptional for this steel, we wrote Mr. Henderson of Messrs. Firth-Derihons, and he assured me it was only ground to obtain the necessary accuracy, but we have again written him asking him to write to Hispano Suiza and get the question finally answered and the point put beyond doubt. We note H1. now agrees that this type of material when properly hardened must have a hard skin of small thickness, and that the hardness is reduced from the skin to the core gradually, and that the steel from which this cylinder was made has therefore the same characteristics as the test pieces supplied by Messrs. Firths. The difference in degree is due to the short time in the furnace with ammonia gas viz. 24 hours, against 80 hours for greatest depth. We are machining cylinders so that they can be ground or not in accordance with the reply we get from Messrs. Firth Derihons. In order that the position may be clearly known, we attach a list of the material which has been delivered to the Works, and upon which the Experimental Department are working. The crankshaft, large gear wheel, pump spindles | ||