Enhancing hardness in SMAW welded joints with low-frequency vibration assistance: an experimental and analytical study

Vibration assisted welding has gained popularity over the years for creating high quality welds and achieving better mechanical properties. The main objective of this research is to use low frequency vibration-assisted welding to optimise the process parameters. This study uses a novel vibratory technique to vibrate the workpiece during shielded metal arc welding at frequencies ranging from 0 to 100 Hz in order to examine the hardness of mild steel plates butt-welded to a thickness of 5 mm. Taguchi Methodology has been applied to optimise the hardness of welded specimens by varying the input variables viz. Current, vibration duration, and vibration frequency. Additionally, the microstructure of welded mild steel plates has been studied using SEM, optical micrographs, and XRD analysis. Results indicated that a low heat input of 80 Amp frequency of vibration of 100 Hz, and duration of vibration of 100 sec demonstrated optimum performance in terms of hardness of welded MS plates. Frequency of vibration has been found to be the most important parameter determining the hardness of the welded joint. Maximum hardness of 97.1643RHN has been found at optimal parameters. As the weld pool is being excited, vibration-assisted welded butt joints exhibit a finer grain structure, suggesting higher hardness values.