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).
The heat treatment, mechanical properties, and various applications of beryllium bronze.
| Identifier | ExFiles\Box 149\4\ scan0344 | |
| Date | 31th May 1937 guessed | |
| - 6 - of putting the beryllium entirely into solution in the copper, producing a condition of maximum ductility. In this condition, the beryllium bronze will have a maximum stress of 35 tons per square inch, an elongation of 36 per cent and a Diamond Pyramid hardness number of about 120 to 125. All cold-work of whatever nature should be applied to the material while it is in this condition. When the part has been worked to its final form, the second stage of the heat-treatment (the tempering) is applied. This consists simply in heating the parts to 350°C [struck through] followed by cooling in air. The time for which the material is exposed to this temperature to give the optimum conditions is one hour. This tempering operation brings beryllium bronze into the condition of maximum mechanical strength and brings about the change from 35/40 tons per square inch maximum stress to 80/100 tons per square inch maximum stress. [Handwritten note correcting the temperature above] 280°C - 300°C APPLICATIONS. The applications of beryllium bronze to the uses of industry are already numerous and well established, and the most important ones include the following: Springs. A material having the properties of beryllium bronze is, of course, ideal for spring manufacture, because the tensile values are equal to those of the spring steels and, in addition, beryllium bronze provides a resistance to corrosion as well as to notch effect, which is not approached any of the known spring steels. Furthermore, its application to springs for electrical instruments and gear is most favourable because of its relatively high electrical conductivity, as compared with other spring materials. It is important also to note that the normal heat-treatment renders beryllium bronze practically immune to diminution in mechanical properties up to a temperature of 300°C. For switches, particularly if the switch parts must also have the properties of springs, relay and circuit-breaker parts, it is of increasing importance. Tests on leaf springs made of hard rolled phosphor bronze containing 5 per cent of tin, and beryllium bronze, shewed that the endurance of the latter was between 40 and 60 times that of the phosphor bronze spring of the same geometrical proportions. For diaphragms for pneumatic, hydraulic, and meteorological instruments, it is essentially suitable, and for firing pins in certain firearms it has been found | ||