4th Asia Conference on Mechanical and Materials Engineering

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Authors: S.R. Harisha, Sathya Shankar Sharma, U. Achutha Kini
Abstract: The high temperature phase austenite in steel has the property to transform into a variety of room temperature phases like coarse pearlite, bainite & martensite depending upon the cooling cycle. The machinability and toughness depend upon the shape and distribution of pro eutectoid harder phases. The spherical or oval shapes give lesser resistance for machining process. So it is required to design the heat treatment to tailor the property as required by the application. In this view, it is proposed to study the mechanical and micro structural properties of EN47 steel undergoing Spheroidization. The aim of this work is to test the hardness, toughness and wear property of the steel in spheroidised condition. Hardening treatment improves hardness of the material, a marginal decrease in hardness value with improved ductility is observed in tempering. Hardening and longer duration tempering show better wear resistance compared to other heat treatments. Both mild and severe wear regions are observed. Generally mild wear region is observed above five hours of continuous running of the specimen. Micro structural analysis shows the existence of pearlitic structure in as bought & normalized specimen, lath martensitic structure in hardened specimen.
Authors: Sathya Shankar Sharma, K. Jagannath, P.R. Prabhu, Shankar M.C. Gowri, S.R. Harisha, U. Achutha Kini
Abstract: Present investigation focusses on combined effect of B4C and SiC on the improvement in hardness with an average size of 35-40μm on Al6061 hybrid composite. Composites are produced by stir casting process. The effect of artificial aging treatment with different aging temperatures of 100, 150 and 200OC on the improvement in hardness is also investigated. Optical micrographs and Brinell hardness number have been discussed. An attempt is made to find out the intermetallic phase responsible for strengthening by Transmission Electron Microscopy. Due to positive response to age hardening treatment there is an improvement in the mechanical properties of Al6061 alloy & its hybrid composite. The aging kinetics is more accelerated in case of hybrid composites as compared to unreinforced Al6061 alloy because of presence of reinforcement particulate, which act as nucleation site for precipitation. Artificially aged at 100OC shows improvement in hardness by 120-220% due to the precipitation of secondary solute rich phase of alloying elements as compared Al6061 alloy.

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