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 sheet for the physical and mechanical properties of 'Hiduminium' 72.
| Identifier | ExFiles\Box 116\2\ scan0135 | |
| Date | 22th December 1939 guessed | |
| Physical and Mechanical Properties of "HIDUMINIUM" 72 SPECIFIC GRAVITY .. .. .. 2.76. WEIGHT PER CUBIC INCH .. .. 0.100 Pounds. CO-EFFICIENT OF THERMAL EXPANSION 20°—100°C. 23.4 x 10⁻⁶. FATIGUE RANGE .. .. .. 11—11.5 tons per sq. in. (In Extruded Heat Treated Conditions only) COMPRESSION PROPERTIES. OF EXTRUDED BAR 0.1% PROOF STRESS .. .. .. .. 27—29 tons per sq. in. 0.5% PROOF STRESS .. .. .. .. 30—32 tons per sq. in. ULTIMATE STRESS .. .. .. .. 46—48 tons per sq. in. TENSILE PROPERTIES. Minimum Specification Figures. | Form | 0.1% Proof Stress Tons per sq. in. | Ult. Stress Tons per sq. in. | Elongation % on 2" G.L. | Brinell Hardness No. | | :--- | :--- | :--- | :--- | :--- | | EXTRUDED BARS AND SECTIONS | 18 | 28 | 15 | 129—148 | | SOLID DRAWN TUBES .. | 22 | 29 | Not called for in Tube Specifications | 129—148 | | ROLLED SHEET .. .. .. | 18 | 28 | 15 | 129—148 | | FORGED BAR as spec. 4L1. .. | 15 | 25 | 15 | 110—130 | | ||