Increase in Mechanical Properties and Damping Capacity of a Cast Mn-Cu Damping Alloy Welded Joint by Pulsed Current TIG Welding

This paper compared the mechanical properties and damping capacity of homogeneous welded joints of Mn-36Cu-3Al-2Zn-2Ni-2Fe (wt.%) cast damping alloy by pulsed and non-pulsed current TIG welding. The results show that the pulsed current makes the microstructure finer in the welded seam due to its rapid solidification of the welding pool and fragmentation of the rough dendrite arm. Tensile and impact tests show that pulsed current welded joints have better mechanical properties than non-pulsed current welded joints, as the strength and toughness of the joints increased by 6.6 and 25.2%, respectively. In addition, according to damping capacity test results, the larger Mn-rich regions in the pulsed current welded seam result in a larger f.c.c-f.c.t phase transformation and more fine martensitic twins. Thus, the damping capacity of the welded joint under pulsed current is 27.6% higher than that under non-pulsed current and far higher than that of the base metal. The addition of pulsed current significantly improves the mechanical properties and damping capacity of the alloy welded joint.