How to control the heating temperature of aluminum alloy forgings?
Will excessively high temperature of aluminum alloy cause cracking?
I. Precision control technology of heating temperature
1. Temperature threshold setting based on alloy grade
| Alloy Series | Commonly used Grades | Start Forging Temperature Range (℃) | End Forging Temperature Lower Limit (℃) | Danger Temperature Range (℃) |
| 6 series | 6061/6082 | 480-520 | ≥350 | >550 (overheating critical temperature) |
| 7 series | 7075/7A04 | 400-450 | ≥320 | >470 (grain boundary melting temperature) |
| 2 series | 2A12/2024 | 460-490 | ≥380 | >500 (eutectic phase melting temperature) |
Example: When a company forges 7075 battery shells, it uses segmented temperature control: in the preheating stage, it is kept at 400℃ for 2h, and then heated to 430℃±5℃ constant temperature to ensure that the β phase (MgZn₂) is fully dissolved, while avoiding the melting of the low melting point eutectic (475℃) at the α+β phase boundary.
2. Heating equipment and temperature control systemGas furnace segmented temperature control: a three-chamber continuous heating furnace (preheating chamber 400℃, heating chamber 450℃, and equalizing chamber 430℃) is used, with an infrared thermometer (accuracy ±3℃), and the furnace temperature uniformity is controlled within ±10℃.
Precise control of electric heating furnace: the vacuum resistance furnace uses the PID intelligent temperature control system to heat up to the set temperature at a rate of 5℃/min, and the fluctuation in the insulation stage is ≤±5℃, which is suitable for sensitive alloys such as the 7 series.
Dynamic compensation of induction heating: For complex-shaped forgings (such as multi-cavity structures of battery shells), medium-frequency induction heating (frequency 20-50kHz) is used to locally compensate the temperature through the eddy current effect, so that the cross-sectional temperature difference is less than 15°C.