The annealing process of oxygen-free copper strip is a key manufacturing process, which can eliminate the structural defects existing in the copper strip and improve the mechanical properties and electrical conductivity of the copper strip. The oxygen-free copper strip annealing process system is determined according to the requirements of alloy properties, work hardening degree and product technical conditions. Its main process parameters are annealing temperature, holding time, heating speed and cooling method. The determination of the annealing process system should meet the following three requirements:
① Ensure uniform heating of the annealed material to ensure uniform structure and performance of the oxygen-free copper strip;
② Ensure that the annealed oxygen-free copper strip is not oxidized and the surface is bright;
③ Save energy, reduce consumption, and increase yield. Therefore, the annealing process system and equipment used for oxygen-free copper strip should meet the above conditions. Such as reasonable furnace design, fast heating speed, protective atmosphere, precise control, easy adjustment, etc.
Selection of annealing temperature for oxygen-free copper strip: In addition to alloy properties and hardening degree, the purpose of annealing should also be considered. For example, the upper limit of annealing temperature should be taken for intermediate annealing, and the annealing time should be appropriately shortened; for finished annealing, focus should be placed on ensuring product quality and performance Uniform, take the lower limit of the annealing temperature, and strictly control the fluctuation of the annealing temperature; the annealing temperature for the large amount of charge is higher than the annealing temperature for the small amount of charge; the annealing temperature of the plate is higher than that of the oxygen-free copper strip.
Annealing heating rate: It should be determined according to the alloy properties, charging amount, furnace structure, heat transfer mode, metal temperature, temperature difference in the furnace and product requirements. Because rapid heating can improve productivity, fine grains, and less oxidation, the intermediate annealing of semi-finished products mostly adopts rapid heating; for the annealing of finished oxygen-free copper strips, with less charge and thin thickness, slow heating is used.
Holding time: When designing the furnace temperature, in order to increase the heating speed, the temperature of the heating section is relatively high. After heating to a certain temperature, it is necessary to carry out heat preservation. At this time, the furnace temperature is similar to the material temperature. The holding time is based on ensuring the uniform heat penetration of the oxygen-free copper strip.
Cooling method: The annealing of the finished product is mostly carried out by air cooling, and the intermediate annealing can sometimes be water-cooled. For alloy materials with severe oxidation, the scale can burst and fall off under rapid cooling. However, alloys with quenching effect are not allowed to be quenched.
In short, the annealing process of oxygen-free copper strip is one of the indispensable key processes in the copper strip manufacturing process. Its process principle and influencing factors need to be carefully studied and analyzed in order to formulate annealing process conditions suitable for oxygen-free copper strip materials. Only through a scientific and reasonable annealing process can high-quality oxygen-free copper strips be produced and contribute to the development of electronics, communications and other fields.
Post time: Jun-21-2023