EFFECTS OF USING VEGETABLE OILS AS AUSTEMPERING QUENCHANTS ON THE MICROSTRUCTE AND MECHANICAL PROPERTIES OF LOW ALLOYED ST STEEL
Publication Date : 01/08/2008
The effect of using local vegetable oils as quenching media in the austempring process of low alloyed cast steel was investigated. Cottonseed, groundnut and shear butter oils were used as quenching- media instead of traditional molten salt bath for austempering process. Specimens were austenitized at 950 C and austempered in the selected hot vegetable oils at 250°C for 1-5hrs. Optical microscopy was used to study the morphology of structures formed at different austempering time. Mechanical properties Were determined by testing standard tensile, hardness and impact specimens. The results showed clear disparity in mechanical properties between these oils. Samples austempercd in shear butter oil recorded the highest tensile strength value of 954N/mm2 and impact strength value of 36J at Stirs. The lowest tensile strength and impact strength values were reported for the austempered samples in hot groundnut oil as 444N/mm2 and 161 respectively at Ihr.However, austempered. sample in hot groundnut oil recorded the highest hardness value of 298HV at lhr. The results showed that austempered samples were able to form a mixture of bainite, martensite and retained austenite at different time.
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