Postheating with a torch

How to cut > How to postheat after thermal cutting

Postheating with a torch

Normally postheat treatment using torches is done manually and it is important to know how to control the temperature. When using torches, it's essential not to overheat. The temperature of the cut edge should not exceed 700°C (1,292°F), preferably maintained between 300 to 500°C (572-932°F). This can be achieved by observing the color of the cut edge at the torch; it should just start to glow a very dark red. If the color is bright cherry red or dark orange, the temperature is too high, and the postheating may not be successful.

Manual postheat treatment using a torche

Glow very dark red at the torch

Alternatively, the temperature can be controlled with an infrared thermometer, pointed directly to the cut edge at the flame. The heat from the torch will temper the re-quenched zone of the HAZ, which will reduce the tensile stresses at the cut edge. The torch used should have a rather big flame with low intensity. This will allow the heat to reach further into the material without heating it too much.

Infrared thermometer

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How to cut How to postheat after thermal cutting

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