Abstract

Solidification process of grey cast iron largely determines the resultant carbon precipitates in form of graphite or carbides. Microstructure and hardness properties of grey iron were therefore studied. Aggregate scraps were melted with varying inoculants composition of 0.1 wt%, 0.2 wt% and 0.3 wt%. Cast produced was shaken out of the mould at various timing. Microstructures of the samples were determined and analyzed. Hardness properties were equally evaluated. It was observed that the occurrence of carbides was more with 0.25 hrs shakeout time than other varying timing. Increasing shakeout time was found to decrease hardness and increase the carbide grain size. When the ferrosilicon content increases, there is a gradual decrease in the hardness properties from 59.6 HRC to 53.2 HRC for 0.25 hrs shakeout time cast sample. Similar decreases were observed for various timing analyzed.

Highlights

  • Cast iron is an alloy that has been used extensively for so many years because of its price, excellent cast ability and good mechanical properties

  • The cast ability of the alloy is as a result of carbon precipitates as graphite during solidification

  • Solidification process by which a metal freezes in the mould plays a vital role in determining the properties of the as cast alloy. This is as a result of: the initial uniform composition in liquid becomes non-uniform as the liquid transform to solid; different solidification gives rise to different microstructures of the solid and some casting defects depend on the manner in which the alloy is solidified in a mould [2]

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Summary

Introduction

Cast iron is an alloy that has been used extensively for so many years because of its price, excellent cast ability and good mechanical properties. The cast ability of the alloy is as a result of carbon precipitates as graphite during solidification. Due to the precipitate of carbon as graphite, there will be an expansion which counteracts the general shrinkage of the metal during solidification [1]. Solidification process by which a metal freezes in the mould plays a vital role in determining the properties of the as cast alloy. This is as a result of: the initial uniform composition in liquid becomes non-uniform as the liquid transform to solid; different solidification gives rise to different microstructures of the solid and some casting defects depend on the manner in which the alloy is solidified in a mould [2]. Solidification structure of any casting has the obvious influence on the final microstructure and properties

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