1. Repair method of cast iron parts

Cast iron is a kind of brittle material, which is more difficult to weld, and has higher requirements for welding technology and material selection. In welding, the welding process will change the microstructure of cast iron, and when the fire is concentrated, it is easy to produce high temperature burns, thermal stress and cooling shrinkage. Therefore, it is necessary to select the correct welding method and master a certain technology to avoid causing greater cracks or damage.

At present, the common methods of cast iron welding are copper electrode oxidation gas welding, gas shielded welding, manual arc welding, brazing and so on. Among them, copper electrode oxidation gas welding is a common method, because it has the advantages of fast welding speed, low cost, good operability and crack resistance.

2. Welding crack repair steps and precautions

(1) Positioning welding crack

Before repairing the cast iron parts, it is necessary to confirm the position and shape of the welding cracks and process them correctly. Welding cracks are generally located in the center of the workpiece, its shape is more complex, the depth and shape of the crack section is also more different. It needs to be positioned according to the actual situation and processed with tools.

(2) Preparation of welding materials and equipment

Iron casting welding requires the selection of appropriate materials and equipment. The welding material should have good toughness and stable mechanical properties, and will not cause excessive damage to the microstructure of the cast iron during the welding process. Suitable materials for use include CHAMBER, MONGOUR alloy, silver welding wire, and the like. Welding equipment should have high stability and reliability to ensure the stability of welding quality.

(3) Pretreatment before welding

Before welding, it is necessary to clean and process the area where the welding crack is located to eliminate the dirt and rust on the metal surface of them, so as to improve the quality of the weld after welding. Before the welding crack is processed, the workpiece needs to be heated to relieve the residual stress in the workpiece.

(4) Welding

The process of welding iron castings is a continuous process, which requires strict compliance with operating procedures and correct welding techniques. The welding process is divided into three steps: preheating, welding and thermal post-treatment.

(5) Thermal post-treatment

After welding, thermal post-treatment is needed to ensure the quality of welding and the stability of microstructure. In the process of thermal post-treatment, the workpiece will be in a high temperature state, and the cooling rate needs to be controlled by water cooling and gas quenching methods to alleviate the residual stress and prevent the occurrence of thermal cracks, so that the cast iron welded workpiece has higher stability and better performance.

3. Summary

Cast iron welding has a wide range of applications in industrial manufacturing, but due to the welding of its microstructure is easy to change, so the welding quality and technical level directly affect its use effect. In the welding process, it is necessary to select the correct welding method and material according to the situation of cast iron parts, and strengthen the pretreatment before welding to reduce the damage of welding. After the welding is completed, thermal post-treatment is very necessary, which can enhance the quality and stability of the welding and extend the service life of the workpiece. It should be noted that during the entire welding process, the operating specifications must be guaranteed and the welding standards must be strictly observed to ensure the quality and stability of the welding.