How to solve the porosity problem after welding of stainless steel electric heating ring?

To solve the problem of pores after welding stainless steel electric heating rings, corresponding measures need to be taken for different reasons, as follows:
Equipment failure
Check the arc welding power supply: regularly maintain and overhaul the arc welding power supply, and use professional electrical testing equipment, such as an oscilloscope, to check whether the current and voltage output by the power supply are stable. If a power supply failure is found, replace the damaged electronic components in time or ask professional maintenance personnel to repair it.
Maintain the wire feeding mechanism: frequently check the wear of the wire feeding wheel, and replace the severely worn wire feeding wheel in time to ensure uniform wire feeding speed. At the same time, clean the impurities and oil in the wire feeding pipeline to ensure smooth wire feeding. In the case of jamming, check whether the welding wire is bent or deformed, and whether the wire feeding motor is working properly. If there is a problem, deal with it or replace it in time.
Inspect the shielding gas supply system: regularly calibrate the gas flow meter to ensure that it measures accurately. Check whether the gas delivery pipeline is blocked or leaking. For blocked pipelines, compressed air can be used for blowing; for leaking parts, seal them in time or replace damaged pipeline components. At the same time, ensure that the purity and pressure of the shielding gas meet the welding requirements.
Parent material
Handle parent material surface defects: Before welding, conduct a comprehensive inspection of the parent material surface. For existing pits, cracks, sand holes and other defects, mechanical processing or grinding can be used to remove them to make the surface smooth. For deeper defects, repair welding is required and then grinding is performed to ensure the surface quality of the parent material and reduce the adsorption of impurities and gases.
Control the gas content of the parent material: When purchasing stainless steel parent materials, require suppliers to provide materials with low gas content and check the relevant quality inspection reports. For parent materials with high gas content, vacuum treatment and other methods can be used for dehydrogenation and denitrification to reduce the gas content in the parent material.
Welding process
Strengthen interlayer cleaning: When welding multiple layers, after welding each layer of weld, use wire brushes, grinders and other tools to thoroughly clean the slag, spatter and other impurities on the weld surface to ensure good interlayer bonding and no impurities remain. After cleaning, compressed air can be used to blow away the cleaned impurities to prevent them from mixing into the molten pool again.
Optimize the welding sequence: According to the structure and size of the stainless steel electric heating ring, formulate a reasonable welding sequence. Generally, the principle of short first, long second, inside first, outside second, and symmetrical welding is followed to make the weldment evenly heated and reduce welding stress and deformation. For example, for electric heating rings with larger diameters, the method of segmented symmetrical welding can be adopted, and the welding can be symmetrically performed from the center of the heating ring to both sides to avoid the gas being wrapped in the weld and unable to be discharged.
Standardized preheating and post-heating: Determine the appropriate preheating temperature and post-heating process according to the material of the stainless steel and the thickness of the weldment. Generally speaking, for thicker stainless steel electric heating rings, the preheating temperature can be controlled between 100-200℃. After welding, post-heating is carried out in time. The post-heating temperature is usually between 200-300℃. The insulation time is determined according to the thickness of the weldment and the restraint of the weld joint, generally 1-2 hours, to promote the full diffusion and escape of the gas in the weld.
In addition, it is necessary to strengthen welder training, improve welder operation skills and quality awareness, so that they can operate strictly in accordance with welding process regulations, which is also an important link in reducing welding defects such as pores.