I. cause analysis
1. The extrusion temperature of industrial aluminum profile is too low and the extrusion speed is too slow. The outlet temperature of the profile in the extruder cannot reach the solid solution temperature and cannot play the role of solid solution strengthening.
2, less fans at the outlet of the profile, air volume is not enough, resulting in a slow cooling speed, can not make the profile in a short time to fall below 200℃, so that the thick Mg2Si precipitate out too early, thus reducing the solid solution phase, affecting the mechanical properties of the profile after heat treatment.
3. The ingot composition is unqualified, and the Mg and Si content in the ingot cannot meet the standard requirements.
4. The ingot was not homogenized, so that the Mg2Si phase precipitated in the ingot tissue could not be redissolved in a short time after extrusion, resulting in insufficient solid solution and affecting the product performance.
5. Improper aging process, poor hot air circulation or incorrect thermocouple installation position lead to insufficient aging or over-aging.
Ii. Solutions
1. Reasonably control the extrusion temperature and extrusion speed to keep the outlet temperature of the extruder above the solid solution temperature.
2. Enhanced air cooling conditions. Atomization cooling devices can be installed in factories where conditions are available to meet the cooling gradient requirements of 6063 alloy.
3. Strengthen the quality management of ingot casting.
4. Homogenize the ingot.
5, reasonable determination of aging process, correct installation of thermocouple, correct placement of profile to ensure smooth hot air circulation.
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