Based on our previous background on the TIG welding repair and stress relief process for hot runner channels experiencing thermal shock cracks, there are specific guidelines regarding the timing of stress relief after repair:
Initial Cooling After Welding: After all welding is completed, allow the hot runner workpiece to cool naturally to room temperature for 2-4 hours. This allows for the initial release of welding stress, preventing sudden stress changes that could occur if the workpiece is directly placed in the furnace.
Optimal Stress Relief Window: Within 12 hours of cooling, initiate overall stress relief annealing. At this time, the residual welding stress is in a state where slow deformation has not yet occurred, resulting in the highest stress relief efficiency, eliminating over 90% of the residual welding stress.
Special Urgent Scenario Requirements: If production is urgent, wait until the workpiece cools to below 100°C before placing it in the furnace. It is strictly forbidden to directly place a freshly welded, high-temperature workpiece into a 600°C heat treatment furnace to avoid secondary temperature shocks that could generate new harmful stresses.
Strictly controlling this timeframe maximizes the stress relief effect and significantly reduces the risk of subsequent hot runner channel cracking.
