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).
Steel specifications for gun barrels, comparing Arsenal and S.A.E. standards.
| Identifier | ExFiles\Box 170\4\ img040 | |
| Date | 24th August 1940 | |
| C O P Y August 24, 1940 Mr. Maurice Olley Rolls-Royce, Inc. Detroit, Michigan Dear Maurice: Gun Barrels Today I got together with Dr. Lester and Mr. Mann of the Watertown Arsenal and obtained the following information with reference to gun barrel steels. 1. General The Arsenal specification for 37 m/m guns and smaller calibres is a Cr.{Mr Cra???ster / Mr Chichester} Mo. Va. of the following analysis: C Mn Cr{Mr Cra???ster / Mr Chichester} Mo Va .25/.35 .60 .90/1.20 .20/.35 .12/.18 They prefer the carbon kept on the low side as compared with S.A.E. 4340 specified in Rm.{William Robotham - Chief Engineer}2 of July 17/40. This S.A.E. standard is: C Mn Ni Cr{Mr Cra???ster / Mr Chichester} Mo .35/.45 .50/.80 1.5/2.0 .5/.8 .30/.40 While the above Cr.{Mr Cra???ster / Mr Chichester} Mo. Va. steel represents the chemistry of the steel held in greatest favor by the Arsenal, they do not purchase on this but on two counts: a) Macroetch b) Tensile test (Yield Point and Reduction of Area) These are further discussed below. In certain cases the Arsenal buy forgings from other analyses, particularly: C Ni Cr{Mr Cra???ster / Mr Chichester} Mo .45 2.5 1.6 .20 provided the mechanical properties are met. They prefer, however, the Cr.{Mr Cra???ster / Mr Chichester} Mo. Va. grade of steel since the higher carbon may lead to temper brittleness even with Mo. present. (See also report of writer of April 30 on Cr.{Mr Cra???ster / Mr Chichester} Mo. Va. steels.) 2. Steel Source The steel can be made either by O.H. or Electric Furnace | ||