In the aluminum extrusion and processing industry, “quenching” is the critical rapid-cooling step used to “freeze” the solid solution of alloying elements, ensuring the material can later achieve its maximum strength through aging. The choice between Online and Offline quenching depends on the alloy type, the complexity of the profile, and the required mechanical properties.
1. Online Quenching (In-line Quenching)
Online quenching occurs immediately after the aluminum profile exits the extrusion die. As the metal is still at its “solution temperature” (usually above 500°C), it is cooled right on the extrusion press’s run-out table.
Core Functions: Rapidly reduces the temperature of the extruded profile to ambient levels using air, water mist, or water baths as it moves along the production line.
Mainstream Models:
Air Quenching Systems: Uses high-velocity fans or blowers. Common for 6063 alloys.
Water Mist/Spray Systems: Uses atomized nozzles for faster cooling. Common for 6061 or 6005 alloys.
Standing Water Wave Quench: The profile passes through a “wave” of water for maximum cooling intensity.
2. Offline Quenching (Vertical/Horizontal Quenching）
Offline quenching is a separate heat-treatment process. The profiles are first extruded and cooled slowly. Later, they are placed into a Solution Heat Treatment Furnace, heated back up to roughly 520°C, and then dropped or pushed into a quench tank.
Core Functions: Provides a controlled environment to re-dissolve alloying elements and performs a high-intensity quench (usually in a vertical water tank) to ensure metallurgical uniformity.
Vertical Quenching Furnaces: Profiles are hung vertically and dropped into a deep water pit. This is the industry standard for aerospace and high-strength structural parts to minimize warping.
Horizontal Batch Furnaces: Used for smaller parts or specific forged components.
3.Summary of Comparison
