Interpreting the weld formations using acoustic emission for the carbon steels and stainless steels welds in servo-based resistance spot welding

Acoustic emission reveals certain characteristic in resistance spot welding process as it exists due to the variation of electromagnetic ties between atomic bounds. So, the objective of this study is to analyse the acoustic patterns of resistance spot welding in a servo-based electrode actuation system. Time and frequency domains’ representations are interchangeably applied to analyse such matters as those behaviours are captured via electronics means. More than one type of weldable materials (carbon steels and stainless steels) is purposely used to analyse the dissimilarity conditions as well as the individual material’s welding processes. The interpreted waveform shows that the welding processes can be significantly put into classes for their behaviour (weld formation) based on acoustic emissions. A best weld formation will have perfect acoustic pattern, while a better one will have more than one main lobe in frequency domain. Moreover, a dissimilar weld formation will have inter-transient spike waveform, while an expulsion welding process will have a rapid drop of signal in acoustic pattern. All these observations have been revealing dissimilar characteristic of welding processes to certain degrees when the fusion process is concerned in resistance spot welding.