This section contains the engineering properties and related characteristics of beryllium used in aerospace structural applications. Beryllium is a lightweight, high modulus, moderate temperature capability metal that is used for specific aerospace applications. Structural designs utilizing beryllium sheet should allow for anisotropy, particularly the very low short transverse properties. Additional information on the fabrication of beryllium may be found in References 7.2.0(a) through (i).
Standard grade beryllium bars, rods, tubing, and machined shapes are produced from vacuum hot-pressed powder with 1½ percent maximum beryllium oxide content. These products are also available in numerous other compositions for special purposes but are not covered in this document. Sheet and plate are fabricated from vacuum hot-pressed powder with 2 percent maximum beryllium oxide content.
Hot Shaping — Beryllium hot-pressed block can be forged and rolled but requires temperatures of 700°F and higher because of brittleness. A temperature range of 1000°F to 1400°F is recommended. Hot shaping procedures are given in more detail in Reference 7.2.0(b).
Forming — Beryllium sheet should be formed at 1300°F to 1350°F, holding at temperature no more than 1.5 hours, for minimum springback. Forming above 1450°F will result in a reduction in strength.
Machining — Carbide tools are most often used in machining beryllium. Mechanical metal removal techniques generally cause microcracks and metallographic twins. Finishing cuts are usually 0.002 to 0.005 inch in depth to minimize surface damage. Although most machining operations are performed without coolant, to avoid contamination of the chips, the use of coolant can reduce the depth of damage and give longer tool life. See Reference 7.2.0(c) for more information. Finish machining should be followed by chemical etching at least 0.002-inch from the surface to remove machining damage. See References 7.2.0(h) and (i). A combination of 1350°F stress relief followed by an 0.0005-inch etch may be necessary for close-tolerance parts. Damage-free metal removal techniques include chemical milling and electrochemical machining. The drilling of sheet may lead to delamination and breakout unless the drillhead is of the controlled torque type and the drills are carbide burr type.
Joining — Parts may be joined mechanically by riveting, but only by squeeze riveting to avoid damage to the beryllium, by bolting, threading, or by press fitting specifically designed to avoid damage. Parts also may be joined by brazing, soldering, braze welding, adhesive bonding, and diffusion bonding. Fusion welding is not recommended. Brazing may be accomplished with zinc, aluminum-silicon, or silver-base filler metals. Many elements, including copper, may cause embrittlement when used as brazing filler metals. However, specific manufacturing techniques have been developed by various beryllium fabricators to use many of the common braze materials. For each method of joining specific detailed procedures must be followed, Reference 7.2.0(f).
Surface Treatment — A surface treatment such as chemical etching to remove the machined surface of metal is recommended to ensure the specified properties. All design allowables herein represent material so treated. This surface treatment is especially important when beryllium is to be mechanically joined. References 7.2.0(d), (h), and (i) contain information on etching solutions and procedures.
Toxicity Hazard — Particles of beryllium and its compounds, such as beryllium oxide, are toxic, so special precautions to prevent inhalation must be taken. References 7.2.1.1(a) through (e) outline the hazard and methods to control it.
Specifications and Properties — Material specifications for standard grade beryllium are presented in Table 7.2.1.0(a).
Room-temperature mechanical and physical properties are shown in Tables 7.2.1.0(b) and (c). Notch tensile test data are available in Reference 7.2.1.1(g). The effect of temperature on physical properties is shown in Figure 7.2.1.0.
| Specification | Form |
|---|---|
| AMS 7906 | Bar, rod, tubing, and mechanical shapes |
| AMS 7902 | Sheet and plate |
| Specification | AMS 7906 |
|---|---|
| Form | Bar, rod, tubing, and machined shapes |
| Condition | Hot pressed (ground and etched) |
| Thickness or diameter, in. | ··· |
| Basis | S |
| Mechanical Properties: | |
| Ftu, ksi: | |
| L | 47 |
| LT | 47 |
| Fty, ksi: | |
| L | 35 |
| LT | 35 |
| Fcy, ksi: | |
| L | ··· |
| LT | ··· |
| Fsu, ksi | ··· |
| Fbru, ksi: | |
| (e/D = 1.5) | ··· |
| (e/D = 2.0) | ··· |
| Fbry, ksi: | |
| (e/D = 1.5) | ··· |
| (e/D = 2.0) | ··· |
| e, percent: | |
| L | 2 |
| LT | 2 |
| E, 103 ksi | 42 |
| Ec, 103 ksi | 42 |
| G, 103 ksi | 20 |
| μ | 0.10 |
| Physical Properties: | |
| ω, lb/in.3 | 0.067 |
| C, K, and α | See Figure 7.2.1.0 |
| Specification | AMS 7902 | |||
|---|---|---|---|---|
| Form | Sheet | Plate | ||
| Condition | Stress relieved (ground and etched) | |||
| Thickness or diameter, in. | 0.020-0.250 | 0.251-0.450 | 0.451-0.600 | ≥0.601 |
| Basis | S | S | S | S |
| Mechanical Properties: | ||||
| Ftu, ksi: | ||||
| L | 70 | 65 | 60 | 40 |
| LT | 70 | 65 | 60 | 40 |
| Fty, ksi: | ||||
| L | 50 | 45 | 40 | 30 |
| LT | 50 | 45 | 40 | 30 |
| Fcy, ksi: | ||||
| L | ··· | ··· | ··· | ··· |
| LT | ··· | ··· | ··· | ··· |
| Fsu, ksi | ··· | ··· | ··· | ··· |
| Fbru, ksi: | ||||
| (e/D = 1.5) | ··· | ··· | ··· | ··· |
| (e/D = 2.0) | ··· | ··· | ··· | ··· |
| Fbry, ksi: | ||||
| (e/D = 1.5) | ··· | ··· | ··· | ··· |
| (e/D = 2.0) | ··· | ··· | ··· | ··· |
| e, percent: | ||||
| L | 10 | 4 | 3 | 1 |
| LT | 10 | 4 | 3 | 1 |
| E, 103 ksi | 42.5 | |||
| Ec, 103 ksi | 42.5 | |||
| G, 103 ksi | 20.0 | |||
| μ | 0.10 (L and LT) | |||
| Physical Properties: | ||||
| ω, lb/in.3 | 0.067 | |||
| C, K, and α | See Figure 7.2.1.0 | |||
The handbook plots these properties on one graph with a separate y-axis for each. Here each one has its own chart, over the same temperature range.
Thermal expansion coefficient (α)
How much the metal grows, per inch, for each °F. Mean value from 70 °F to the temperature shown. Units: 10⁻⁶ in/in/°F. Metric: × 1.8 = 10⁻⁶/K
Thermal conductivity (K)
How fast heat flows through the metal, at the temperature shown. Units: Btu/(hr·ft·°F). Metric: × 1.731 = W/(m·K)
Specific heat (C)
Heat needed to warm 1 lb of the metal by 1 °F, at the temperature shown. Units: Btu/(lb·°F). Metric: × 4.187 = kJ/(kg·K)
Figure 7.2.1.0. Effect of temperature on the physical properties of beryllium (2% maximum BeO).
The effect of temperature on the mechanical properties of hot-pressed beryllium is presented in Figures 7.2.1.1.1 and 7.2.1.1.4.
Figure 7.2.1.1.1. Effect of temperature on the tensile ultimate strength (Ftu) and tensile yield strength (Fty) of hot-pressed beryllium bar, rod, tubing, and machined shapes. Strength at temperature, exposure up to 1/2 hr.
Figure 7.2.1.1.4. Effect of temperature on the tensile and compressive moduli (E and Ec) of hot-pressed beryllium bar, rod, tubing, and machined shapes. Modulus at temperature, exposure up to 1/2 hr. Typical.
- 7.2.0(a)Williams, R. F., and Ingels, S. E., “The Fabrication of Beryllium—Volume I: A Survey of Current Technology,” NASA TM X-53453 (July 1966).
- 7.2.0(b)Williams, R. F., and Ingels, S. E., “The Fabrication of Beryllium Alloys—Volume II: Forming Techniques for Beryllium Alloys,” NASA TM X-43453 (July 1966).
- 7.2.0(c)Williams, R. F., and Ingels, S. E., “The Fabrication of Beryllium—Volume III: Metal Removal Techniques,” NASA TM X-53453 (August 1966).
- 7.2.0(d)Williams, R. F., and Ingels, S. E., “The Fabrication of Beryllium—Volume IV: Surface Treatments for Beryllium Alloys,” NASA TM X-53453 (July 1966).
- 7.2.0(e)Williams, R. F., and Ingels, S. E., “The Fabrication of Beryllium—Volume V: Thermal Treatments for Beryllium Alloys,” NASA TM X-53453 (July 1966).
- 7.2.0(f)Williams, R. F., and Ingels, S. E., “The Fabrication of Beryllium—Volume VI: Joining Techniques for Beryllium Alloys,” NASA TM X-53453 (July 1966).
- 7.2.0(g)Stonehouse, A. J., and Marder, J. M., “Beryllium,” ASM Metals Handbook, Tenth Edition, Vol. 2, pp. 683-687, 1990.
- 7.2.0(h)Hanafee, J. E., “Effect of Annealing and Etching on Machine Damage In Structural Beryllium,” J. Applied Metal Working, Vol. 1, No. 3, pp. 41-51 (1980).
- 7.2.0(i)Corle, R. R., Leslie, W. W., and Brewer, A. W., “The Testing and Heat Treating of Beryllium for Machine Damage Removal,” RFP-3084, Rockwell International, Rocky Flats Plant, DOE, Sept. 1981.
- 7.2.1.1(a)Breslen, A. U., and Harris, W. B., “Health Protection in Beryllium Facilities, Summary of Ten Years' Experience,” U.S. Atomic Energy Commission, Health and Safety Laboratory, New York Operations Office, Report HASL-36 (May 1, 1958).
- 7.2.1.1(b)Breslen, A. U., and Harris, W. B., “Practical Ways to Collect Beryllium Dust,” Air Engineering, 2(7), p. 34 (July 1960).
- 7.2.1.1(c)Cholak, J., et al., “Toxicity of Beryllium, Final Technical Engineering Report,” ASD TR 62-7-665 (April 1962).
- 7.2.1.1(d)“Beryllium Disease and Its Control,” AMA Arch. Ind. Health, 19(2), pp. 91-267 (February 1959).
- 7.2.1.1(e)Stokinger, H. E., “Beryllium, Its Industrial Hygiene Aspect,” Academic Press (1966).
- 7.2.1.1(f)Rossman, M. D., Preuss, O. P., and Powers, M. B., Beryllium-Biomedical and Environmental Aspects, Williams and Wilkins, Baltimore, Hong Kong, London, Munich, San Francisco, Sydney, and Tokyo, 319 pages (1991).
- 7.2.1.1(g)Crawford, R. F., and Barnes, A. B., “Strength Efficiency and Design Data for Beryllium Structures,” ASD TR 61-692 (1961).