Characteristics of Beryllium Copper Material

Beryllium bronze is a type of bronze with beryllium as the main additive element. The beryllium content of beryllium bronze is 0.2% to 2%, and a small amount (0.2% to 2.0%) of cobalt or nickel as a third component is added. This alloy can be strengthened by heat treatment. It is an ideal high conductivity and high-strength elastic material. Beryllium bronze is non-magnetic, spark resistant, wear-resistant, corrosion-resistant, fatigue resistant, and stress relaxation resistant. And it is easy to cast and shape by pressure processing. The typical uses of beryllium bronze castings are as molds for plastics or glass, electrodes for resistance welding, explosion-proof tools for petroleum applications, and protective covers for submarine cables. The typical uses of beryllium bronze processing materials are as current carrying springs, connectors, contacts, fastening springs, leaf springs and coil springs, bellows, and lead frames in electronic devices.

Beryllium bronze is divided into two categories. According to the alloy composition, beryllium bronze with a beryllium content of 0.2% to 0.6% is highly conductive (electrical, thermal) beryllium bronze; High strength beryllium bronze with a beryllium content of 1.6% to 2.0%. According to the manufacturing process, it can be divided into cast beryllium bronze and deformed beryllium bronze. The internationally recognized beryllium bronze alloy grades are led by C. There are two main types of deformed beryllium bronze: C17000, C17200 (high-strength beryllium bronze), and C17500 (high conductivity beryllium bronze). The corresponding cast beryllium bronze includes C82000, C82200 (high conductivity cast beryllium copper) and C82400, C82500, C82600, C82800 (high-strength wear-resistant cast beryllium copper). The world's largest producer of beryllium copper alloy is Brush Wellman from the United States, whose enterprise standards correspond to international standards and have a certain degree of authority. The history of producing beryllium bronze in China is almost synchronous with countries such as the former Soviet Union and the United States, but the only grades listed in national standards are high-strength beryllium bronze QBe1.9, QBe2.0, and QBe1.7. Other high conductivity beryllium bronze or cast beryllium bronze have been put into large-scale production according to the needs of the development of the petroleum and defense industries.

Beryllium bronze has excellent comprehensive properties. Its mechanical properties, including strength, hardness, wear resistance, and fatigue resistance, rank first among copper alloys. Its conductivity, thermal conductivity, non-magnetic properties, and spark resistance cannot be compared to other copper materials. In the solid solution soft state, the strength and conductivity of beryllium bronze are at their lowest values. After work hardening, the strength increases, but the conductivity remains at its lowest value. After aging heat treatment, its strength and conductivity significantly increased.

The machining performance, welding performance, and polishing performance of beryllium bronze are similar to those of general high copper alloys. In order to improve the machining performance of the alloy and meet the precision requirements of precision parts, various countries have developed a high-strength beryllium bronze (C17300) containing 0.2% to 0.6% lead. Its various properties are equivalent to C17200, but the cutting coefficient of the alloy has been increased from 20% to 60% (100% for free cutting brass).

Beryllium bronze is a typical age precipitation strengthened alloy. The typical heat treatment process for high-strength beryllium bronze is to hold it at a temperature of 760-830 ℃ for an appropriate period of time (at least 60 minutes for every 25mm thick plate), so that the solute atom beryllium is fully dissolved in the copper matrix, forming an alpha phase supersaturated solid solution with a face centered cubic lattice. Subsequently, the dissolution and precipitation process is completed by holding at a temperature of 320-340 ℃ for 2-3 hours, forming the γ 'phase (CuBe2 metastable phase). This phase coexists with the matrix to create a stress field and strengthen the matrix. The typical heat treatment process for high conductivity beryllium bronze is to hold it at a high temperature of 900-950 ℃ for a period of time to complete the solid solution process, followed by holding it at 450-480 ℃ for 2-4 hours to achieve the dissolution and precipitation process. Due to the addition of a large amount of cobalt or nickel in the alloy, the dispersed strengthening particles are mostly intermetallic compounds formed between cobalt or nickel and beryllium. To further improve the strength of the alloy, a certain degree of cold working is often performed on the alloy after solution heat treatment and before aging heat treatment, aiming to achieve a comprehensive strengthening effect of cold work hardening and aging hardening. Its cold processing degree generally does not exceed 37%. Solution heat treatment should generally be carried out by alloy production plants. Users will use the strip that has undergone solution heat treatment and cold rolling to produce parts, which will then undergo self aging heat treatment to obtain high-strength spring components. In recent years, the United States has developed strip materials that have undergone aging heat treatment by beryllium copper manufacturers, and customers can directly punch them into parts for use. After various processing techniques, the letter representation of the alloy state for beryllium bronze in Europe and America is: A represents the annealed state, where the alloy is in its softest state and is easy to press and form. It needs further cold working or direct aging strengthening treatment. H represents the work hardened state (hard). Taking cold-rolled sheet as an example, 37% of the cold working degree is fully hard (H), 21% of the cold working degree is semi hard (1/2H), and 11% of the cold working degree is 1/4 hard (1/4H). Users can choose the appropriate soft and hard state according to the difficulty of punching the part shape. T represents the heat treatment state that has been strengthened by aging. If the process of comprehensive strengthening through deformation and aging is adopted, its state is represented by HT. [1]

safety protection

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The beryllium contained in beryllium bronze alloy has a mass percentage of 2%, but an atomic percentage of 9.0122%. Beryllium oxide (BeO) is formed during high-temperature operations such as melting, casting, heat treatment, welding, and cutting. Most beryllium oxide will firmly adhere to the surface of the original workpiece, but during intense movements such as cutting, polishing, welding, etc., fine particles (less than 10 μ m) of dust will be suspended in the air. If the operator inhales too much, it can lead to occupational diseases such as beryllium lung. Therefore, the above working environment must have a complete directional exhaust device. Cutting, polishing and other processes must be carried out in a moist state with coolant. The standard set by the Occupational Safety and Health Administration (OSHA) in the United States is to conduct regular air sampling of beryllium product workshops and their surrounding environments. For workers who work for 8 hours a day, the beryllium content in their working environment must not exceed 2 μ g/m3. In order to reduce the pollution caused by beryllium copper, China and Japan have developed titanium and similar elasticity in recent years, which can be used as a good substitute material for beryllium bronze in some workplaces.