Effects of Thermal Frequency on Microstructures, Mechanical and Corrosion Properties of AA6061 Joints

Abstract

Three thermal frequencies that were designated as 3, 4, and 5 Hz were used to reveal the microstructural evolution, mechanical, and corrosion properties of AA6061-T6 sheets that were welded by double pulsed gas metal arc welding (DP-GMAW) using microstructural observations, microhardness tests, tensile tests, bend tests, impact tests, and corrosion tests. A self-developed welding system consisted of a digital multifunctional welder and an arc dynamic waveform wavelet analyzer was chosen to perform welding operations and to record electrical signal waveforms during the welding process. The results show that the process of DP-GMAW was stable, and the weld beads exhibited aesthetic ripples. The ripple distance, the grain size, and porosity of the fusion zone decreased with an increasing thermal frequency. Microhardness and corrosion properties of the weld joint improved when the thermal frequency increased. In addition, all of the joints exhibited excellent bending properties. However, the impact property of the weld joint was lower than that of the BM. It indicated that the low impact energy results of the welded AA6061-T6 sheet were mainly due to the formation of micro-cracks in the fusion zone.

Stability and Heat Input Controllability of Two Different Modulations for Double-Pulse MIG Welding

“…Strong and weak pulse trains are continuously alternated during this process, which forces gases formed by the welding processes out of the weld. Therefore, double-pulse MIG welding reduces the effects of weld pores, reduces the sensitivity of the joint to cracks, and improves the finish and mechanical properties of the weld [18].…”

Double pulse gas metal arc welding process parameter optimization and weld performance analysis based on response surface method

“…Xue et al [17] used the RSM combined with the grey wolf algorithm to optimize the process parameters and improve the weld profile and performance. In summary, optimizing welding process parameters using RSM is already common, but there is still a lack of optimization for DP-GMAW process parameters [18][19][20].…”

Effect of low heat-input double-pulse gas metal arc welding on weld formation and microstructure of 6061 aluminium alloy

“…Wu et al [18] introduced a dual-wire DP-GMAW with a median current waveform based on the conventional rectangular pulse and found that changed the median current, the average welding current also changed. The research on increasing the stirring effect of the molten pool mainly includes low-frequency [19, 20], current amplitude [21], and additional technology [22]. Liu et al [23] observed the change of the molten pool profile during the DP-GMAW welding process and found that the molten pool profile changes periodically with the change of low-frequency.…”