Induction heat treatment technology for manufacturing elastic sensitive components and highly conductive elastic components

In order to obtain overall good properties, copper-based high elastic alloys can be tempered within a certain range after quenching and cold deformation. The notable features of copper-based alloys are their excellent electrical conductivity and atmospheric corrosion resistance. It is mainly used to manufacture elastic sensitive components, and is also used to manufacture elastic components that require high conductivity, such as brush blades and reeds in electrical appliances, and tension wires and hairsprings in instruments.

The alloy elements of copper-based elastic alloys include tin, beryllium, titanium, manganese, silicon, phosphorus, chromium, aluminum, etc. According to the hardening characteristics, alloys can be divided into two categories: work hardening and age hardening.

1. Work-hardened copper-based elastic alloys. This type of alloy is widely used in various tin bronzes, silicon bronzes and some white copper alloys. Their typical grades, ingredients, properties, features and applications.

Adding 0.05-0.5% to tin bronze can significantly improve strength, elastic limit, elastic modulus and fatigue strength. Tin-phosphor bronze is the most important instrument spring material. A certain amount of zinc is incorporated into tin bronze to improve the mechanical properties. To ensure plasticity, the addition amount should not exceed 4%. Tin-zinc bronze has good corrosion resistance and is mainly used to manufacture leaf springs and round springs in electrical appliances and precision machinery. Silicon can dissolve more in copper, and silicon bronze has good plastic processing properties. In order to improve performance, a small amount of manganese, nickel, tin and other elements are also added. The processing performance of silicon-manganese bronze is similar to that of rust steel. It is used as spring material in the chemical industry, shipbuilding, papermaking and petroleum industries, and can be made into plates, rods and wires. It does not rust in the air and is stable in various salt solutions and organic acids. It is a widely used elastic material in instruments, precision machinery, and medical equipment.

After the alloy is annealed at 600-650℃ or 700-750℃, it has a single-phase structure, low hardness and good plasticity. They cannot be strengthened by heat treatment but can be work hardened. In order to improve strength and obtain high elasticity, cold deformation processing can generally only be used. In order to further increase the elastic limit and reduce the elastic aftereffect, a short period of low-temperature recovery annealing can be performed after cold deformation. The recovery annealing system is: heating to 150-300℃ and holding for 0.5-1.0h. During the recovery process, the interaction between solute atoms and defects occurs, resulting in a hardening effect without softening.

2. Age-hardening copper-based high elastic alloy

⑴Characteristics of alloys. Beryllium bronze and titanium bronze have high strength, high elasticity, high elastic energy storage, good electrical conductivity, high hardness and wear resistance; they are heat-resistant, corrosion-resistant, fatigue-resistant and low-temperature resistant, non-magnetic and do not produce sparks during impact. It has good cold and hot processing properties, easy to braze and electroplat, and is a highly conductive elastic alloy with good comprehensive properties. They are widely used in the manufacture of important elastic components in electrical appliances, instruments, and precision machinery, especially conductive and wear-resistant components. Adding trace elements to beryllium bronze can slow down the decomposition of supersaturated solid solution and inhibit grain boundary reactions and the softening process of over-aging. Adding aluminum to titanium bronze can improve the oxidation resistance and heat resistance, improve the effective hardening effect, and increase the hardness and strength.

⑵Heat treatment of alloy. When beryllium bronze is heated to 780-800°C and titanium bronze is heated to 850-900°C and quickly cooled, a supersaturated solid solution can be obtained, which improves the plasticity and reduces the hardness, facilitates component processing, and prepares for age hardening.

Solution treatment is key to component quality and performance. During solid solution treatment of beryllium bronze, the surface must first be cleaned with an organic solvent; heated in a protective atmosphere, quickly quenched into cooling water below 25-30°C after insulation, and dried immediately to avoid rust. Before the aging peak (300-350°C), the elastic limit increases with the increase in deformation. In order to obtain better overall properties, the aging temperature of cold deformed alloys is slightly lower than that of cold deformed alloys. Cold deformation is generally 20-40%。