Study on the thermo-effect of P-GMAW characterized by structure-borne acoustic emission signals detected in welding on aluminum alloy

According to the structure-borne acoustic emission (AE) signals detected in pulsed gas metal arc welding (P-GMAW), the effects of welding heat input and pulses to the microstructures and the characteristics of AE signals were analyzed. The experiment results showed that the welding arc was the source of most vibration energy in GMAW. The increase of welding heat input caused the growth of grain in weld and the increase of average AE count. The mean grain size was increased with the average AE count increasing, which was attributable to the welding heat input. Both the welding arc and the pulses used in welding were the source of vibration energy in P-GMAW. The mean grain size decreased with the average AE count increasing, which was attributable to the pulses provide additional vibration energy to refine the grain structure. The welding heat input effect played a more important role than the pulses effect to the grain structure in P-GMAW.