How to avoid cracks during repair welding of high carbon steel parts
1) The main measures to improve the welding thermal cycle and reduce the cooling rate of the joint are preheating before welding. It can reduce the hardness of the heat-affected zone, and reduce the residual stress and deformation, thereby effectively preventing cracks in the weld and the heat-affected zone. Each layer of weld can play a preheating effect on the next weld, and also play a slow cooling effect on the previous weld, thus playing a good role in preventing cracks. After welding, slow cooling and stress-relieving treatment have a good effect on cracks.
2) Select the appropriate electrode. Use low-hydrogen electrode as much as possible to enhance the crack resistance of the weld. The electrode should be dried and placed in a heat preservation cylinder as required. The strength grade of the electrode should be the same as that of the base metal.
3) Strengthen the cleaning of the weld area to thoroughly remove any sources of hydrogen that may enter the weld, such as oil, water, rust and other impurities.
4) Try to reduce the proportion of the base metal melted into the weld, such as opening a V-shaped groove, welding the first layer of the weld with a small current, etc. are all effective methods. However, care must be taken to penetrate the base metal to avoid defects such as slag inclusion and incomplete penetration.
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