Preheating before welding | Preheating temperature
During welding of steel the structure inside the heat affected zone (beside the seam) becomes a hardness intensity which is negative for the quality. The process of hardness increases more quickly depending on the temperature difference between the seam and the area beside the seam. Therefore the welding parts need to be heated up to minimize the hardness intensity. The temperature to avoid cold cracks depends on the thickness of the work pieces, the heat dissipation, the alloy of the material and the heat treatment during the welding process.