Main cause analysis:
① When extruding aluminum profiles, if the temperature is too low or the extrusion speed is too slow, the profile at the outlet of the extruder cannot reach the solution temperature, and the solution strengthening effect cannot be achieved;
② There are too few fans at the profile outlet or the airflow is insufficient, resulting in a slow cooling rate, preventing the profile from dropping below 200°C in the shortest time, causing the coarse Mg2Si to precipitate prematurely, thereby reducing the solution phase and affecting the mechanical properties of the profile after heat treatment;
③ The composition of the ingot is unqualified, with Mg and Si contents in the ingot not meeting the standard requirements;
④ The ingot has not been homogenized, so the Mg2Si phase precipitated in the ingot structure cannot be re-solved in the short time of extrusion, leading to insufficient solution and affecting product performance;
⑤ Improper aging process, poor hot air circulation, or incorrect installation position of the thermocouple, resulting in insufficient or overaging.
Solution:
① Reasonably control the extrusion temperature and extrusion speed, keeping the profile temperature at the extruder outlet above the minimum solution heat treatment temperature;
② Strengthen air cooling conditions, and factories with the capability can install atomizing cooling devices to meet the minimum cooling gradient requirements of 6063 alloy;
③ Strengthen the quality management of ingots;
④ Carry out homogenization treatment of ingots;
⑤ Properly determine the aging process, correctly install thermocouples, and properly place profiles to ensure smooth hot air circulation. Geometrical size deviations.
