The quenching of the aluminum alloy is to obtain a metastable supersaturated solid solution in a rapid quenching manner of the solid solution formed during the solution heat treatment, in order to obtain high strength and sufficient plasticity in the subsequent aging.
1. selection of quenching temperatureIndustrial aluminum alloy quenching temperature depends on the composition of the alloy and the eutectic temperature. Some bismuth-strength aluminum alloys with high alloy content and required toughness control need to control the temperature within a tighter range, but must be lower than the eutectic transition temperature.
When quenching and heating, the more fully dissolved in the solid solution in the alloy, the more uniform the composition of the solid solution, the higher the mechanical properties after quenching and aging. In general, the higher the heating temperature, the faster and more complete the above process. However, if the temperature is too high, the crystal grains will be coarse, and even the over-burning (local melting) will occur, and the product will be scrapped. If the heating temperature of the bonfire is low, the heat-treated parts are insufficiently heated, and the strengthening phase cannot be completely dissolved, resulting in a large decrease in the concentration of the solid solution and a corresponding decrease in the final strength and hardness. Therefore, quenching heating temperature is an important process parameter. The heating temperature range of the aluminum alloy is very narrow. Therefore, the temperature error of the heat treatment furnace should be small, usually within ±5 °C, so that the mechanical properties and metallographic structure of the aluminum alloy can be guaranteed.
2. solution treatment time
At the normal solution heat treatment temperature, the undissolved or precipitated soluble phase composition is brought to a satisfactory degree of dissolution and the holding time required for the solid solution to be sufficiently uniform, with the microstructure and heating method before the heat treatment (salt bath and air circulation furnace) ) and the processing state of the part, the composition of the alloy, the size of the part, and the like. The higher the heating temperature, the higher the rate at which the strengthening phase dissolves into the solid solution, and the shorter the holding time. The state before quenching (such as the size, distribution state, and molding method of the strengthening phase) also has a great influence on the holding time. Some alloys (such as 6063, 2A50, etc.) where the grains are easily coarsened at the heating temperature should be kept as short as possible under the conditions of hardening to avoid grain growth. In the case of a deformed alloy, the degree of deformation is large, and the required holding time is shorter than the degree of deformation. The alloy of the repellent has a thicker reinforcing phase and a longer holding time. Parts with a large amount of furnace capacity and large size have a longer holding time. If the amount of furnace is small and the interval between parts is large, the time for insulation should be shorter.
Now you know why the temperature is so important to quench, please contact us if you have any questions.