Stable and metastable solidification of cast iron

Jones, Stephen Bruce (1971). Stable and metastable solidification of cast iron. University of Birmingham. Ph.D.

Preview

Jones1971PhD.pdf
Text - Accepted Version
Available under License All rights reserved.
Download (18MB) | Preview

Abstract

The stable to metastable eutectic transition was studied in three cast •irons with carbon equivalents of 4.0 and silicon contents of 1.00$, 2.04$ and 2.43$. Castings were produced in sand moulds containing a solid steel chill as well as in heated and unheated ceramic moulds* cooled at one end by a water cooled copper chill. Structural variations obtained were analysed with reference to physical conditions of cooling within the castings and compositional differences between the alloys.
Transformations in white and mottled structures during freezing or near the freezing temperature were studied by rapid solidification and isothermal treatments in heated metal moulds. Castings produced in a polished copper chill mould had plane surfaces enabling study of nucleation and growth processes under chill conditions. The 2.04$ Si alloy was used as a base for the addition of a range of pure elements to study structural variations in heated ceramic mould castings.
Thermal analysis, macrostructures and microstructural examinations indicate that metastable eutectic may partly or fully decompose during the cooling of a casting. Microstructural examinations by optical and scanning electron microscopes provide evidence of such decomposition. Etching in alkaline sodium picrate or bromine solution was found valuable for this purpose.
Amounts of carbide decomposition increased with increasing silicon content and transformation temperature, and decreased as post-solidification cooling rates increased. Solidification of hypoeutectic alloys at chill surfaces may produce areas containing primary cementite needles.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):