Modification and Fabrication of Quenching Machine: Influence of Agitation and Temperature Gradient on Hardness of Al 6050 Alloy

The QTS 124 agitation quench tank manufactured by L&L Special furnace Co. Inc to be used for uniform quenching of hot metals was redesigned, modified and developed for the purpose of this research. After modification the equipment can be used with different quenching media such as water, oil, light polymer and brine. Other distinguishing features introduced in the machine are electric heater and thermostat so that quenchant can be pre-heated to different temperatures to determine the effect of temperature gradient on hardness of metals and also obtain the optimum initial quenching temperature of quenchant for the desired mechanical property of any metal during heat treatment. Performance evaluation of the machine was carried out with as-cast Al 6050 alloy heated to 350C and was quenched in water and oil from 20C at 10C interval to 80C with and without agitation of the quenchant. The results showed that for both water and oil hardness decreases as quenchant temperature increases with and without agitation. Uniform and steady rate of cooling was achieved by agitation of samples in the quenching media. Also from hardness values obtained, water has greater effect on hardness of Al 6050 alloy when compared to oil for dimension of the specimen used.