Introduction
Due to an effort to reduce vehicle weights to enhance vehicle fuel efficiency, innovative high-strength steels are frequently used to both reduce the vehicle weight and to improve passenger safety. Resistance spot welding (RSW) is the most commonly used method of joining metal sheets in car-body manufacturing because of its low cost, speed, cleanliness and ease of automation.
However, the designed microstructure of steel sheets is changed during the RSW process due to the welding thermal cycle. The microstructural evolution during RSW is highly dependent on the welding parameters. These changes influence the mechanical strength of the steel structures. Finding a good way to ejaculate the strength of an RSW using Non-Destructive Testing (NDT) is important to be able to assure good welds are being produced.
NDT Inspection of Resistance Spot Welds (RSW)
Ultrasonic Non-Destructive Testing (NDT) systems have been used to inspect RSW’s for weld quality for several years. It is important to make sure that the NDT system you choose uses appropriate algorithms and methodologies to provide accurate results. Before relying on NDT systems to provide meaningful information, it is a good idea to correlate the results from the NDT system with results from destructive testing.
NDT testing will provide you with better results if your destructive testing results are accurate. Here are a few points to make sure you have a reliable process to do destructive testing.
- Train your operators well.
- Make sure they have the right equipment to provide accurate results.
- Stress the importance of accurate readings.
You want to compare the results of the NDT system to the integrity and strength found from destructive testing. Extensive testing can help you develop a strong correlation between the NDT results and the destructive testing results. The more you do comparative testing between NDT and destructive testing, the more you can rely on the results from the NDT in a production environment.
Conclusion
Using the right ultrasonic NDT system combined with well correlated data from destruction testing can provide your organization with a good solution to ensure the integrity of resistance spot welds.