Title page for ETD etd-07032009-120615


Document Type Master's Dissertation
Author Raseroka, Mantsaye Sophie
Email mantsaye.raseroka@eskom.co.za
URN etd-07032009-120615
Document Title Controlled chloride cracking of austenitic stainless steel
Degree MSc
Department Materials Science and Metallurgical Engineering
Supervisor
Advisor Name Title
Prof P C Pistorius Supervisor
Keywords
  • temperature
  • scc
  • chloride stress corrosion cracking
  • austenitic stainless steel
  • strain
  • corrosion fatigue
  • Type 304L stainless steel
  • crack density
Date 2009-04-28
Availability unrestricted
Abstract

Type 304 stainless steel is used in various applications where corrosion resistance is required. This material is selected for weldability and corrosion resistance, but it can suffer stress corrosion cracking (scc), corrosion fatigue, pitting and crevice corrosion in chloride environments. The aim of this project was to produce Type 304 containers with intentional stress corrosion cracks, to serve as test samples for future weld repair trials.

A test rig was constructed which used thermal stress to crack Type 304 tube samples; a central Type 310 stainless steel bar contained a heating element, so that the bar serve as a heat source and a stressing element. The rig was filled or half filled with magnesium chloride solution. The elastic strain in the tube sample was directly related to the temperature difference between the central bar and the sample. The thermal stress was sufficient to cause stress corrosion cracking. The tests were terminated when the first crack extended through the wall thickness of the 304 tube sample. The distribution and depth of cracks were determined after the tests. The test procedure caused the formation of multiple cracks in the tube sample.

The temperature controller caused cyclical variation in the bar temperature and hence in the thermal stress. However, the temperature variation did not have an effect on cracking; corrosion fatigue did not contribute to cracking, and the cracks had the classic branched transgranular morphology of chloride cracking.

Copyright 2008, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria

Please cite as follows:

Raseroka, MS 2008, Controlled chloride cracking of austenitic stainless steel, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07032009-120615/ >

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