What is the heat treatment process of A286 key locking insert?

The heat treatment process for A286 key locking inserts primarily consists of two stages: solution treatment and aging. The specific process parameters and steps are as follows:

1. Solution Treatment
– Temperature Range: Typically, heating at 982°C (1800°F) for one hour, followed by rapid cooling. Some standards recommend holding at 899°C for two hours, followed by rapid cooling.
– Cooling Method: Typically, air cooling or oil quenching is used.
– Purpose: High-temperature heating dissolves carbides and nitrides in the alloy, resulting in a single-phase austenite structure, relieving processing stresses, and improving the toughness and ductility of the material.

2. Aging Treatment
– Temperature Range: 704-760°C (1300-1400°F).
– Holding Time: Typically 12-16 hours, followed by air cooling.

3. Special Treatment
– Double Aging: In some cases, a double aging treatment is performed. This involves holding at 704/760°C for 16 hours, then air cooling to 649°C, holding for another 8-12 hours, and finally air cooling. This treatment further improves notch cracking strength while maintaining a balance between toughness and hardness.
– Dimensional Change: After aging, the material will shrink slightly, approximately 0.001 in/in.

4. Precautions
– Temperature Control: The temperatures of the solution and aging treatments must be strictly controlled to ensure optimal material properties.
– Cooling Rate: The cooling rate after solution treatment has a significant impact on material properties. Rapid cooling helps achieve a fine grain structure, thereby improving toughness.
– Repeated Aging: In some cases, multiple aging treatments may be necessary to further optimize material properties.

Through this heat treatment process, the A286 key locking insert achieves excellent high-temperature strength, corrosion resistance, and good processing properties, meeting the application requirements of demanding fields such as aerospace.