Date of Award

2012

Degree Type

Thesis

Degree Name

Master of Engineering Science

School

School of Engineering

Faculty

Computing, Health and Science

First Advisor

Associate Professor Laichang Zhang

Second Advisor

Dr Zonghan Xie

Abstract

Cold drawn eutectoid steel wires have been widely used for a variety of applications, such as suspension bridges, steel cords for automobile tires, and springs. Much research has been done to increase their mechanical strength. With advances in modern production technology, both the drawing speed and the quality of drawn steels have been enhanced. After a careful literature survey, it is obvious that some issues are still controversial. As Y.S. Yang, J.G. Bae and C.G. Park mentioned, the lamellar spacing, thickness and volume fraction of cementites have all reached the nanometer regime, and the conventional theory is not enough to explain it. Besides, the cementite dissolution is a huge problem to the performance, according to Y.S. Yang and C.G. Park. To address the above issues, a systematic study has been taken on the wire drawing process under the conditions of the industrial production. Through the morphology, microscopic, mechanical and comprehensive analysis, a clear understanding of the microstructures and associated professing conditions of the high-strength carbon steel wires has been obtained. This project aims to clarify why the mechanical properties improve with the increasing strain. The project will be carried out in four stages: 1) characterisation of the microstructure of the cold drawn steel wires; 2) measurements of the modulus, hardness and toughness of steel wires; 3) modelling the deformation behaviour of the cold drawn steels. The techniques involved in the project include X-ray diffraction (XRD), focus ion beam (FIB), scan electron spectrum (SEM), Nanoindentation. A deep understanding of the relationship between composition, structure and performance will be achieved in this project. The results may provide the basis for improving cold-drawn steel wire designs.

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