Typical Heating And Cooling Cycle For Furnace Brazing

1. Hold #1: At 150 to 260 °C (300 to 500 °F) for 10 to15 minutes. This allows solvents or water in the paste or binder vehicle to out gas from the braze alloy deposit.

• Helps to prevent eruptions (holes) in the brazed deposit
• Restore the atmosphere quality which can degrade from gasses

2. Hold #2: At approximately 540 °C (1000 °F) for 10 to15 minutes. This allows the organics (not liquids) in the braze vehicle sufficient time to become gaseous and to be removed through the pumping system.

• Allows time for the quality of the furnace atmosphere to return

3. Hold #3: At 10 to 38 °C (50 to 100 °F) below braze alloy solidus temperature.

• Stabilization hold for a minimum of ten minutes or until part thermo couples have reached set Delta T

Ramp Up Rate: Heat as fast as possible (without part distortion or compromise of metallurgical properties) to the braze temperature to prevent liquation of the braze alloy.

4. Hold #4: Typically, a hold time of 0 to 60 minutes at the braze temperature allows sufficient time for the alloy to melt and flow into the joint.

Ramp Down Rate: Slowly reduce the temperature to allow liquid alloy to solidify in place. Begin to quench below the solidus temperature of the braze alloy.


5. Hold #5: A diffusion hold of two to four hours at 1065 to 1150 °C (1950 to 2100 °F) will allow boron to diffuse and raise remelt temperature of the braze alloy.

Cooling Ramp: Use a rate that will control distortion, meet required metallurgical properties and production needs.