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).
Specification for Low Carbon Air Hardening Nickel Chrome Steel for carburizing, noted for use in Phantom III reverse gears and shafts.
| Identifier | ExFiles\Box 126\3\ scan0060 | |
| Date | 1st August 1922 | |
| Handwritten (top left): Reverse Driving Gear. 1st spd. gear! Reverse gears & shaft } Ph III Typed Text: August 1st, 1922. ROLLS-ROYCE LIMITED. Specification No. 236. MATERIAL. Low Carbon Air Hardening Nickel Chrome Steel (for Carburizing). ANALYSIS. Carbon . . . . . . . . . .14% to .18% Silicon (maximum) . . . . . . . . . .30% Manganese . . . . . . . . . .35% to .45% Nickel . . . . . . . . . . 4.0 % to 4.5 % Chromium . . . . . . . . . . 1.0 % to 1.30% HARDNESS FORMULA. Hardness Figure is calculated by the following formula :- 7C. plus 2 (MN. plus Cr.{Mr Cra???ster / Mr Chichester}) plus Ni. GRADING. Hardness Figure, Bar or Billet up to 15/16" . . . 7.7 to 8.3 " " " 1" to 2" . . . . . 8.1 to 8.6 " " " 2 1/16" to 3" . . . . . 8.5 to 8.9 " " " above 3" . . . . . 8.9 to 9.4 TESTS. HEAT TREATMENT OF TEST PIECES. (1) Test Piece should be an integral part of the forging it represents if this is possible, in any case the dia. of the Test Piece as treated should not be less than 1 1/8" dia. (2) Heat to 900°C. in sand for 4 hours. (3) Heat to 820°C. and quench in oil. (4) Heat to 800-810°C. and cool in air (see also Section 5 below). (5) Alternative to Section 4 above. Where this material is required for Aero Engine work, the final heat should be 760°C. and quench in oil. (6) Machine test bar in accordance with Drawing Requirements. PHYSICAL PROPERTIES. Should the material be finally heated to 800-810°C. and cooled in air, the following minimum figures should be obtained :- M.S. Y.P. E.{Mr Elliott - Chief Engineer} R.A. (1) Tensile. 68 tons sq. in. 18.5% 50% (2) Stanton. 6,500 blows. (3) Brinell. 302-341. (302 is struck through) (4) Izod. 40 ft. lbs. (if required). If the material has been finally quenched in oil from 760°C. the Tensile strength should be :- MINIMUM. M.S. Y.P. E.{Mr Elliott - Chief Engineer} R.A. 85 tons per 75 tons per 12% 35% (Column crossed out with an X) sq. in. sq. in. Handwritten (bottom): Case Hardness 341 - 400 Brinell Case - C57 - C62 Rockwell - 750/820 Vickers. Depth of case after grinding .025" - .035". | ||