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).
Comparison between the existing standard steel and a proposed new steel for use in aero engine connecting rod bolts.
| Identifier | ExFiles\Box 154a\1\ scan0247 | |
| Date | 10th February 1932 | |
| R.{Sir Henry Royce} [crossed out] Wg.{Mr Gill - Financial Director} [crossed out] c. Wes- [crossed out] c. Hs.{Lord Ernest Hives - Chair} [crossed out] X1474 BY.4/G.10.2.32. CONNECTING ROD BOLT STEEL FOR AERO ENGINES. --------------------------------------- I am definitely of the opinion that for such parts as connecting rod bolts, particularly as the speeds of the whole of our engines are increasing, that we should use a nickel chrome molybdenum steel in place of our present standard 3 1/2% nickel. It is essential that we should have ductility and therefore in order to obtain increased tensile capacity without reducing the ductility it means that we must adopt a more expensive steel in order to meet such requirements. The figures for the two steels are as follows :- (1). PRESENT STANDARD 3 1/2% NICKEL STEEL. Brinell ... 269 Ultimate Tensile. ... 56 Tons. Yield Point ... 46 Tons. Elongation ... 22% Reduction in Area ... 60% Izod ... 60 ft. lbs. (2). PROPOSED NICKEL CHROME STEEL. Brinell ... 321 Ultimate Tensile ... 70 Tons. Yield Point ... 63 Tons. Elongation ... 20% Reduction in Area ... 64% Izod ... 75 ft. lbs. The use of the steel proposed above would definitely preclude the possibility of stretching a bolt, even if an increased length of spanner were used, unless the increase in length became excessive, and even then the reduction in area is of such an order as to ensure the bolts being able to deform locally without setting up a fracture, the net. result of such deformation being that the tensile strength would be increased in proportion to the deformation, and the material | ||