1. Stress-relieving annealing treatment of copper alloys. Copper alloy wires and strips such as tin bronze, silicon bronze, aluminum bronze, cupronickel, etc. have been cold-drawn and strengthened when they are supplied. After cold-formed coiled springs, only stress-relieving annealing treatment is required . The strength increased slightly after treatment, but the strength decreased when the temperature exceeded 220C. 2. Aging treatment of beryllium bronze When the beryllium bronze ribbon material is supplied, it has undergone solution treatment and cold drawing processing. After the spring is formed, the aging treatment is carried out to make the beryllium precipitate around the grain boundary in a dispersed state and increase the strength of the material. Table 1 lists the aging process of beryllium bronze and the comparison of tensile strength before and after aging.
Table 1 Aging specification and strength comparison of beryllium bronze before and after aging
Keep temperature time
Tensile strength, σb/MPa
3. Quenching and tempering of copper alloys Aluminum bronze, chromium bronze and aluminum cupronickel with an aluminum mass fraction greater than 9% are all copper alloys that are quenched and tempered.
Taking aluminum bronze as an example, the quenching temperature should be selected to transform the alloy structure into a single unit. Phase, and then cool quickly. For aluminum bronze with an aluminum content of 9% to 10%, this temperature is about 1000 deaths, which is close to the melting temperature of the alloy. Therefore, the quenching temperature should be slightly lower than this temperature, generally 850-950C. Holding time, generally 1-2h, cooling in water.
The tempering temperature is determined according to the required mechanical properties. When high strength, high hardness and low plasticity are required, low temperature tempering can be used at a temperature of 250-350℃; when higher strength, hardness, and high plasticity and toughness are required, high temperature tempering can be used, and the temperature is 500-650’C. The tempering time is generally about 2h.
The copper alloy quenching and tempering process specifications are shown in Table 2.
Table 2 Copper alloy quenching and tempering process specification