Technical Factors That Affect The Quality of Welded Joints

The technical factors that affect the quality of welded joints include the following:

1. Materials
This includes both the base metal and the filler metal. For Shielded Metal Arc Welding (SMAW), E4303 electrodes must be properly dried before use. For Carbon Dioxide (CO2) Gas Shielded Welding, the CO2 gas purity must be ≥99.5%, and H08Mn2SiA welding wire should be used.

2. Welding Methods and Processes
The selected welding method must be suitable for the properties of the base metal and the specific welding position. Process control also involves surface preparation, such as shot blasting and overall grinding of the steel ring to remove rust and dirt, which helps mitigate welding stress.

3. Stress
The presence of residual stress in welded joints is a primary cause of various types of cracks. As mentioned above, stress can be eliminated or reduced through methods like shot blasting and grinding the steel ring, which simultaneously removes rust and dirt.

4. Geometric Shapes
The geometry of the joint significantly influences stress distribution. A higher stress concentration factor will have a greater negative impact on the structural integrity and quality of the weld.

5. Environment
When the service environment involves corrosive conditions, high or low temperatures, or fluctuating climate conditions, these factors must be taken into account, as they can significantly influence the formation of welding defects and the long-term quality of the joint.

6. Post-Weld Treatment
Post-weld treatment includes post-weld heat treatment (PWHT) and post-weld mechanical treatment. An example of PWHT is the process used for wheel rims, where the component is welded first and then heat-treated to reduce residual welding stress. An example of mechanical treatment is the grinding of weld beads to improve surface finish and geometry.