Formability of Metal-Matrix Composite based on Aluminium Alloy 6061 - Reinforced with Silicon Carbide Particulars

Abstract

Aluminium alloy reinforced with hard ceramic materials has improved specific strength, specific modulus and wear resistance . Increasing amount of these reinforcing materials decreases ductility and CTE values . Many of these properties are desirable in aerospace , marine and automotive applications . There is no substantial data available as regards to forming characteristics of newly developed composite alloy.The present work has been undertaken with a view to assess quantitatively the forming behavior of 6061-Al/SiCPcomposites developed through conventional casting routes.The cast composites were upset tested and drawn during study of formability. Ring compression tests developed by Male and Cockcroft have been used for determining the friction factor during upsetting of rings . The reduction capacity test was modelled using Avitzur 's equations for forging of thin discs to estimate friction factor during upset forging a solid cylindrical disk under dry conditions . Friction factor has been estimated using a computer based on equation developed by Venugopal et al.Increasing silicon carbide content from 10 vol% to 20 vol% resulted in decreased formability based on upset test. Initially this decrease was of the order of 20% which later decreased by 25%. The rate of decrease of formability was more pronounced beyond 15 vol% of silicon carbide particulate addition . Paper reports the systematic investigation carried out with composite rings of geometry 6:3:2 (OD:ID:Height) under different lubricating conditions to estimate co-efficient of friction.Interfacial frictional value decreased on changing the lubricating conditions from dry to 220 grade lubricant, and this was of the order of 20-25%. Lubricant 220 and furnace oil were foun to have similar characteristics between 25-45% deformation in height. Paper also reports the results of reduction capacity test during upset forging of samples with aspect ratio of 2 and 2.5. It was revealed that the friction factor has strong dependence on deformation percentage. The friction factors determined by means of ring compression test and reduction capacity test with aspect ratio 2 are not in good agreement in cast Al 6061-SIC r composite, however, they are very close when aspect ratio was increased to 2.5. Further work on forming behaviour of the composite is in progress and it is expected that these will fill up the existing gap in the development of metal matrix composites.