The quality assurance of welding processing runs through the four core links of raw material control, process execution, process inspection, and finished product acceptance, forming a full process closed-loop control. The specific measures are as follows:
1. Raw material and welding material control
- The base material needs to provide Material Certification (MTC), and the main materials such as carbon steel, stainless steel, and aluminum alloy should undergo spectral testing before being stored to ensure that the material grade and composition meet the standards;
- The welding materials (welding rods, welding wires, protective gases) should be strictly matched with the base metal (such as stainless steel with stainless steel welding wire, aluminum alloy with argon arc welding special wire). The welding materials should be dried, insulated and stored according to specifications to prevent moisture from affecting the quality of the weld.
2. Standardized process execution
- Develop exclusive Welding Process Guidelines (WPS) for different materials, thicknesses, and welding types, specifying parameters such as welding current, voltage, speed, and groove angle;
- Welders must hold a certificate (such as a welder qualification certificate) before taking up their posts, and special welds (heavy and precision parts) must pass the Process Qualification Review (PQR);
- Before welding, clean the oil stains, rust, and oxide layer on the base metal groove. After welding, perform annealing and aging treatment on heavy components to eliminate welding stress and prevent deformation and cracking.
3. Full process inspection
- Appearance inspection: The weld seam is formed uniformly, without defects such as porosity, slag inclusion, cracks, undercutting, etc. The excess height and weld leg size meet the requirements of the drawing;
- Non destructive testing: Key load-bearing welds (such as construction machinery bases and pressure vessel fittings) need to undergo UT (ultrasonic), MT (magnetic particle), or RT (radiographic) testing to ensure that there are no hidden defects inside;
- Dimensional accuracy testing: After welding, deformation is corrected through CNC machining, and key dimensions are measured using calipers and coordinate measuring instruments, with tolerances controlled within ± 0.05~0.2mm.
4. Finished product acceptance and traceability
- The finished product needs to undergo mechanical performance sampling (such as tensile and bending tests) to ensure that the weld strength is not lower than the base metal standard;
- Perform rust prevention treatment before surface treatment (painting, galvanizing, passivation) to prevent corrosion in the later stage;
- Establish a production traceability system, retain process parameters and inspection reports for each batch of welded parts, and support quality traceability.