International Journal of Advancements in Mechanical and Aeronautical Engineering
Author(s) : BIPIN KUMAR SRIVASTAVA, JYOTI PRAKASH , S. P. TEWARI
In AA6101 T6 aluminium alloy, the weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often causes inferior weld mechanical properties and poor resistance to hot cracking. But when Gas Metal Arc Welding(GMAW) process under oscillatory condition is used then enhancement in mechanical properties noticed. Total cooling rate increases due to weld pool oscillation. Stirring of the weld pool increases the effective value of the thermal conductivity of the liquid pool because heat transfer in the weld pool becomes more effective. This helps nuclei in the weld pool survive and hence promote the formation of equiaxed fine grains in the fusion zone. In the present work, tensile properties, micro hardness, microstructure of the GMAW joints have been evaluated, and the results are compared with oscillated GMAW joints. It is found that GMAW joints under oscillatory condition ( optimum at amplitude 5 micro metre, Frequency 400 hertz) of AA6101 T6 alloy showed superior tensile properties compared with stationary GMAW joints, and this is mainly due to the formation of very fine, equiaxed microstructure in the weld zone.