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

• Main Authors: Jayashree PK, Gowrishankar MC, Sathyashankara Sharma, Raviraj Shetty, Manjunath Shettar, Pavan Hiremath
• Format: Article
• Language: English
• Published: Elsevier 2020-05-01
• Series: Journal of Materials Research and Technology
• Subjects: Al6061 alloy; Homogenization; Artificial aging; Microstructure; Intermetallics; Interdentritic segregation
• Online Access: http://www.sciencedirect.com/science/article/pii/S2238785420301083

The present work deals with fractograph analysis and enhancement of mechanical properties like hardness and tensile strength on Al6061-SiC reinforced composites during homogenization and artificial aging at 100, 150 and 200 °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 μm 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 β-AlFeSi and α-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 combination 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 structural 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 °C and 90% increase in UTS of composites aged at 100 °C is observed when compared with as weld condition after homogenizing and aging.