CHARACTERISATION OF COLD ROLLED SPRAY FORMED Al-Pb ALLOYS

Abstract

Spray forming is a process of producing net shape preibrin having less number of processing steps. It is also called spray casting or spray deposition, which is the inert gas atomization of a liquid metal stream into variously sited droplets. lhese droplets are interrupted by a substrate on which dense preform collects and solidifies. In present study a convergentdivergent nozzle is used to atomize the melt ofAl-Pb alloy. Al-2OPb alloy is produced by this technique. Spray formed samples are rolled at room temperature on two high rolling mills. The porosity, hardness, wear, and micro structural features of Al-Pb spray formed alloy are .1 analyzed from top to bottom and centre to periphery of the deposit after the cold rolling process. Optical micrographs are taken for samples of spray formed Al-Pb alloy before & alter the cold rolling process. In micrographs. the grain boundaries are shown with uniformly distributed Pb content with the distance from centre to periphery. It remains constant with thickness of the spray formed deposit. Porosity decreases with reduction in thickness of samples due to cold rolling process. I'retorm hardness increased from centre to periphery of the samples and it remains constant with increase in distance from bottom to top of the deposit. Hardness is increased due to difl rent percentage reduction in thickness during cold rolling process. Wear testing of spray Formed Al-Pb alloy is conducted using a pin on disc type wear testing machine. Wear rate behavior is observed with applied load which is categorized into three stages for samples before & after cold rolling process for different thickness reduction. Wear rate was lowest in second stage & highest in final stage