Effect of Porosity on Tensile Behaviour of Welded AA6061-T6 Aluminium Alloy

Abstract

Effect of porosity distribution in the weld metal of AA 6061-T6 with 6 mm thickness plate using two dissimilar filler metals in the gas metal arc welding (GMAW) process was investigated. This paper provides a characterization of the porosity in term of the distribution, location and size of the pores in the weldment region. The porosity characterization was made by using 3D X-Ray Computed Tomography and Scanning Electron microscope. The existing pores resulting from the cause of the filler metal in welded alloy used ER4043 (Al-5Si) was compared with the weldement used ER5356 (Al-5Mg). From this investigation, it is exhibited that the pores only distributed and located mainly at the edges and at the root of the weldment with ER5356 weld metal, however, for weldment with ER4043, the pores were mainly scattered in the centre region. The distribution and location of pores in weld metal is believed due to the effect of convections in the molten metal, solidification rate and also from the gases induced during the weld process. Apart from that, results of tensile test indicated the weldment has affected the strength and ductility of the two different fillers selected. AA6061 with ER5356 are dropped 50% in ultimate tensile strength (UTS) and 40 % in elongation; meanwhile AA6061 with ER 4043 was dropped 70% in UTS and 90% in elongation. The different principle alloying element of these two filler metals have play significant role in the distribution of porosity in AA6061 weldment and had influence the strength and ductility of the weld joint.