Influence of homogenization and aging on tensile strength and fracture behavior of TIG welded Al6061-SiC composites

The present work deals with fractograph analysis and enhancement of mechanical prop- erties like hardness and tensile strength on Al6061-SiC reinforced composites during homogenization and artificial aging at 100, 150 and 200 degrees C. Scanning Electron Microscope, followed by high end metallography testing techniques like, SEM, XRD, EDS etc. are used in the present study for characterization analysis. Metal matrix composites having 0, 8, 10 and 12 wt.% fractions of silicon carbide grits of average 25 mu m size, are TIG welded using the filler material ER5356. Mechanical tests showed higher hardness and lower tensile strength for Al6061-12 wt.% SiC composite under non-homogenized and artificially aged condition owing to the presence of coarse micro-segregation of beta-AlFeSi and alpha-Al(Fe, Mn) Si phase. Microstructure confirms dendritic segregation in non-homogenized specimen and after homogenizing, dendritic segregations are minimized leading to an improvement in hardness and tensile strength. Fracture surfaces of non-homogenized and artificially aged samples indicated the existence of shrinkage porosity and accordingly failure along the interdendritic regions. Homogenized and age hardened composites failed under combi- nation of brittle and ductile mode as evident by the presence of equiaxial fine dimples. Amongst different kinds of the recently developed composites, particle reinforced metal matrix composites have a great demand and has led to the emergence of numerous struc- tural composite materials as candidates for a wide variety of industrial applications like in marine, aerospace and automobile. Property enhancement is witnessed due to the combined effect of homogenizing and lower temperature aging. 60% escalation in ultimate tensile strength of composites aged at 200 degrees C and 90% increase in UTS of composites aged at 100 degrees C is observed when compared with as weld condition after homogenizing and aging. (c) 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).