abstract
An ultrasonic C-scan technique was evaluated for non-destructive testing (NDT) of resistance spot
welding of aluminium. It was established through fundamental trials that removal of surface
indentation from the welding electrode is necessary in order to obtain credible non-destructive
assessments of aluminium spot weld size and shape. The non-destructive test results showed good
correlation with peeled samples and metallographic cross sections. The technique also provided further
fundamental understanding of aluminium resistance spot welding (RSW) process; especially with
respect to the presence of an outer fused ring. The fundamental aspect of this study was underpinned
using the NDT technique for a real assembly; challenging the technique with access issues, different
material combinations, multiple joint stacks and independent measurements. The non-destructive test
analyses obtained correlated well with actual tear down results and offered further encouragement that
the C-scan technique is viable as a production tool if a suitably flattened surface can be provided.