Weldability Study of Tungsten Inert Gas Welded Al-8%SiC Metal Matrix Composite Using Response Surface Methodology

Abstract - Over the years Metal Matix Composite (MMC) has developed into a very essential material for modern manufacturing processes. Particularly aluminium based MMCs have a widespread importance due to their physical and chemical properties which make them applicable for aviation and aerospace industries. Manufacturing and processing in these industries involve joining procedures, wherein welding plays a primary role. This paper investigates on the weldability of Al-8%SiC MMC by using Tungsten Inert Gas (TIG) welding process. Autogeneous bead on plate TIG welding was performed using argon (99.99% pure) as shielding gas. The factors of Heat Input (kJ/mm), Gas flow rate (lt/min) and Weld Torch Angle (degree) were considered as the input parameters with three levels each. These parameters have considerable effect on the weldability of the base material. In welding, the Bead Geometry (depth of penetration, height of reinforcement and bead width) of the weld bead is a salient feature in welded components. It has a considerable effect on mechanical properties of the weld. The effects of heat input, gas flow rate and weld torch angle on bead geometry were investigated. Central Composite Design of Response Surface Methodology was used as the Design of Experiment for formation of the experimental array. Experimental plots for each bead geometry entities were performed using Minitab 16 software. Also, the effect of individual factors on responses was examined by Analysis of Variance (ANOVA). Optimal weld condition was obtained at heat input of 0.510 kJ/mm, gas flow rate of 14 l/min and weld torch angle of 45º. The corresponding depth of penetration being 1.768 mm, bead width of 3.013 mm and height of reinforcement of 0.114 mm. Key Words: Weldability, Metal matrix composite, Aluminium, Bead geometry, Response Surface Methodology