What temperature must the weld reach after the removal of the head riser and before further processing?

In thermite welding, it is crucial for the weld temperature to reach a specific level after the removal of the head riser before any further processing can take place. The correct answer is 900 degrees.

At this temperature, the molten weld metal has developed sufficient strength and adherence to the base metal, ensuring a solid bond. If the weld does not reach this temperature, it may not have completed the necessary metallurgical transformations, which can lead to weaknesses in the joint when subjected to stress or handling. Additionally, waiting until the weld reaches this temperature helps to ensure that all reactions and solidifications are properly completed, leading to an overall stronger and more reliable weld joint.

Reaching 900 degrees also facilitates the proper cooling phase, minimizing the potential for defects such as cracks or incomplete fusion. It's essential to monitor the temperature closely to ensure that the metallurgical integrity of the weld is maintained during subsequent processing steps.