University of Windsor Scholarship at UWindsor Electronic Theses and Dissertations Theses, Dissertations, and Major Papers 2013 Comparison of Austempering and Quench-and-Tempering Processes for Carburized Automotive Steels Andrew Clark University of Windsor Follow this and additional works at: https://scholar.uwindsor.ca/etd Recommended Citation Clark, Andrew, "Comparison of Austempering and Quench-and-Tempering Processes for Carburized Automotive Steels" (2013). Electronic Theses and Dissertations. 4919. https://scholar.uwindsor.ca/etd/4919 This online database contains the full-text of PhD dissertations and Masters’ theses of University of Windsor students from 1954 forward. These documents are made available for personal study and research purposes only, in accordance with the Canadian Copyright Act and the Creative Commons license—CC BY-NC-ND (Attribution, Non-Commercial, No Derivative Works). Under this license, works must always be attributed to the copyright holder (original author), cannot be used for any commercial purposes, and may not be altered. Any other use would require the permission of the copyright holder. Students may inquire about withdrawing their dissertation and/or thesis from this database. For additional inquiries, please contact the repository administrator via email ([email protected]) or by telephone at 519-253-3000ext. 3208. Comparison of Austempering and Quench-and-Tempering Processes for Carburized Automotive Steels by Andrew Clark A Thesis Submitted to the Faculty of Graduate Studies through Engineering Materials in Partial Fulfilment of the Requirements for the Degree of Master of Applied Science at the University of Windsor Windsor, Ontario, Canada 2013 © 2013 Andrew Clark Comparison of Austempering and Quench-and-Tempering Processes for Carburized Automotive Steels by Andrew Clark APPROVED BY: Dr. W. Abdul-Kader Department of Industrial and Manufacturing Systems Engineering Dr. X. Sun Chrysler LLC. Dr. J. Sokolowski Department of Mechanical, Automotive, and Materials Engineering Dr. D.O. Northwood, Co-Advisor Department of Mechanical, Automotive, and Materials Engineering Dr. R.J. Bowers, Co-Advisor Department of Mechanical, Automotive, and Materials Engineering 13 June 2013 DECLARATION OF CO-AUTHORSHIP / PREVIOUS PUBLICATION 1. Co-Authorship Declaration I hereby declare that this thesis incorporates material that is the result of joint research with Xichen Sun and Peter Bauerle of the Chrysler Headquarters and Test Center, Michigan USA, and Derek O. Northwood and Randy J. Bowers of the University of Windsor, Ontario. The research collaboration is covered in Chapter 4 of the thesis. In all cases, the key ideas, primary contributions, data analysis, and interpretation were performed by the author, and the contribution of co-authors was in the capacity of the research in the form of technical advice and suggestions. I am aware of the University of Windsor Senate Policy on Authorship and I certify that I have properly acknowledged the contribution of other researchers to my thesis, and have obtained permission from each of the co-authors to include the above materials in my thesis. I certify that, with the above qualification, this thesis, and the research to which it refers, is the product of my own work. 2. Declaration of Previous Publication This thesis includes one original paper that has previously been published in peer reviewed conference proceedings, as follows: Thesis Publication title/full citation Publication Chapter status Chapter 3,4 Clark, A. D., D. O. Northwood, R. J. Bowers, X. Published Sun, and P. Bauerle. "Comparison of Austempering and Quench-and-Tempering Processes for Carburized Automotive Steels." SAE International Journal of Materials and Manufacturing 6 (2) (2013): 146-153. iii I certify that I have obtained permission from the copyright owners to include the above published material in my thesis, and that the above material describes work completed during my registration as a graduate student at the University of Windsor. I declare that, to the best of my knowledge, my thesis does not infringe upon anyone’s copyright, nor violate any proprietary rights and that any ideas, techniques, quotations, or any other material from the work of other people included in my thesis, published or otherwise, are fully acknowledged in accordance with the standard referencing practices. To the extent that I have included copyrighted material that surpasses the bounds of fair dealing within the meaning of the Canada Copyright Act, I certify that I have obtained permission from the copyright owners to include such materials in my thesis. I declare that this is a true copy of my thesis, including any final revisions, as approved by my thesis committee and the Graduate Studies office, and that this thesis has not been submitted for a higher degree to any other university or institution. iv ABSTRACT Austempering was examined as a replacement for the current quench-and- tempering process as a method of heat treating carburized low alloy steel automotive components. Three carburizing grade steels, SAE 8620, 4320, and 8822, were carburized and heat treated by both processes. Twelve austempering and three quench-and- tempering parameters were used. The effect of heat treatment on the case and core microstructures was examined. Distortion was characterized using Navy C-ring samples, which were measured before and after the carburizing and heat treatment process. X-ray diffraction was used to measure residual stress and retained austenite. Charpy impact and Rockwell C hardness testing were performed. Austempering produced improved distortion and residual stress characteristics over quench-and-tempering, while maintaining similar or improved mechanical properties. Full data sets for distortion and mechanical properties were developed. Wear and fatigue testing are identified as necessary next steps to fully examine the viability replacing the quench-and-tempering process with austempering. v This thesis is dedicated to George Henry Clark vi ACKNOWLEDGEMENTS First, I would like to thank my advisors Dr. Derek O. Northwood and Dr. Randy Bowers for their patience, support, and encouragement during the past two years. It is through their invaluable guidance that I was able to learn the skills I need to succeed in the workplace. I would also like to thank Dr. Xichen Sun and Peter Bauerle from Chrysler LLC, who provided both technical suggestions and coordinated the testing which took place at the Chrysler Headquarters and Technology Center in Auburn Hills, Michigan. Special thanks are also extended to Proto Manufacturing Ltd. in Oldcastle, Ontario, whose X-ray diffraction services were generously provided. Graciously acknowledged is the financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Ontario College-University Consortium Council. vii TABLE OF CONTENTS DECLARATION OF CO-AUTHORSHIP / PREVIOUS PUBLICATION .............. iii ABSTRACT ................................................................................................................... v DEDICATION..................................................................................................................vi ACKNOWLEDGEMENTS .........................................................................................vii LIST OF TABLES ......................................................................................................... x LIST OF FIGURES ...................................................................................................... xi LIST OF ABBREVIATIONS .................................................................................... xiii I. INTRODUCTION ...................................................................................................... 1 1.1 Driving Force for Research .................................................................................... 2 II. LITERATURE REVIEW ......................................................................................... 3 2.1 Steel Microstructure ............................................................................................... 3 2.2 Alloying Effect on the TTT Curve ........................................................................ 10 2.3 Case Hardening .................................................................................................... 11 2.4 Heat Treatment Processes ..................................................................................... 12 2.5 Distortion Effects ................................................................................................. 15 2.5.1 The Navy C-Ring ........................................................................................... 16 2.6 Residual Stress ..................................................................................................... 17 2.7 Retained Austenite ............................................................................................... 21 2.8 Mechanical Properties .......................................................................................... 22 2.8.1 Hardness ........................................................................................................ 22 2.8.2 Toughness...................................................................................................... 23 III. EXPERIMENTAL DETAILS .............................................................................. 24 3.1 Material Selection ...............................................................................................