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Accurate Measurement of Hydrogen in Steel University of Calgary PRISM: University of Calgary's Digital Repository Graduate Studies The Vault: Electronic Theses and Dissertations 2013-04-29 Accurate Measurement of Hydrogen in Steel Senadheera, Thushanthi D.A.A. Senadheera, T. D. (2013). Accurate Measurement of Hydrogen in Steel (Unpublished doctoral thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/24654 http://hdl.handle.net/11023/629 doctoral thesis University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. Downloaded from PRISM: https://prism.ucalgary.ca THE UNIVERSITY OF CALGARY Accurate Measurement of Hydrogen in Steel by Thushanthi D.A.A.Senadheera A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERING CALGARY, ALBERTA April, 2013 c Thushanthi D.A.A.Senadheera 2013 UNIVERSITY OF CALGARY FACULTY OF GRADUATE STUDIES The undersigned certify that they have read, and recommend to the Faculty of Grad- uate Studies for acceptance, a thesis entitled \Accurate Measurement of Hydrogen in Steel" submitted by Thushanthi D.A.A.Senadheera in partial fulfillment of the requirements for the degree of Doctor of Philosophy. ii Abstract Accurate measurement of hydrogen in steels is one of the greatest challenges in the field of applied science. Even though research on hydrogen in steels has been carried out over the last ten decades, very little progress has been made in fundamental areas because of the lack of a reliable method for measuring hydrogen within a steel. The hydrogen atom's small size and its one atomic orbit have caused difficulties in applying readily established measuring techniques to measure the simplest atom. The small size of the hydrogen atom has also made leak proofing the hydrogen mea- suring systems extremely difficult; thus, most apparatus are vulnerable to leaking. Additionally, the need to measure extremely small quantities and the high degree of statistical variation in the measured quantities have made the measured hydrogen quantities uncertain. The main task of this research study was to design and construct a new, di- rect hydrogen measuring device called the Temperature Vacuum Hydrogen System (TVHS) and to explore some higher temperature measurements of hydrogen in steel using this new device. This thesis provides a study of the direct hydrogen measuring methods available, the improvements implemented on the standard eudiometer method to improve the method's accuracy and the users' safety, a discussion of the problems faced during the construction and operation of the TVHS, and the solutions applied to mitigate them. The hydrogen volumes measured using the TVHS at 50o, 150o, 250o, and 350o C in hydrogen charged AISI 1020 steel samples; and temperature-time relationships for measured hydrogen quantities; an equation to correlate the measured amounts iii from the TVHS method with the amounts measured using the standard eudiometer method are also provided in this thesis. Key findings of the tests carried out using the TVHS were that a significantly higher amount of hydrogen egressed at 350o C compared to the amounts that egressed at lower test temperatures and the time durations took longer than expected for stabilizing the egressed hydrogen amounts. Equations to predict hydrogen amounts egress from steel samples that are charged with low hydrogen concentrations were also derived. In addition, a chemical analysis on a steel sample immersed in mercury at low-elevated temperatures for an extended period showed a possibility for hot mercury to dissolute carbon from the pearlite structure of the steel, leaving the iron in the structure. iv Acknowledgements It is with immense gratitude that I acknowledge my thesis supervisor Professor W.J.D. (Bill) Shaw for teaching me Design & Materials for the last twelve years, supporting me while I explored my research interests, and holding me to the highest academic standard. It has been a great privilege to spend several years in the Department of Mechan- ical & Manufacturing Engineering at the University of Calgary and its academic, technical, and administrative staff, and my colleagues will always remain dear to me. The support of the technical staff at the Engineering Workshop, the Engineer- ing Store and the Microscope & Imaging facility at the Health Science Center is etched in my mind. I also grateful to the Teaching Assistantships from the Univer- sity of Calgary, the Province of Alberta Graduate Scholarship fund and Dr. Shaw's research grants for providing financial assistance for me during the initial years of the thesis. This thesis would have remained a dream had it not been for the continuous sup- ports of the management and my colleagues at the National Energy Board, Canada; particularly, I am thankful to Sandy Lapointe, Patrick Smyth, Dr. Iain Colquhoun, Dr. Alan Murray (former professional leader) and the team leaders of the Operation Business Unit. I greatly appreciate my husband Roh (Rohitha) Senadheera for all his support and encouragement, and my children (Lavindu & Chenaya Senadheera) for keeping me oriented and waiting patiently until I completed the thesis, which I have been working on since the days they were born. Their love was my driving force. Last but v not least, I thank my parents (A.A. Alfred & Nanda Dissanayake) and little niece, Sanole Wickramasooriya, for their encouraging words over the phone even being 14,000 kilometers away from me and for my grandmother (Kumarihami Ratnayake) for showing me \who you are is what you dreamed of." T.D.A.A.S. vi To my first teachers -my parents- and the other dedicated teachers I have met who have inspired and shaped me. vii Table of Contents Approval Page ii Abstract iii Acknowledgements v Table of Contents viii Nomenclature xxii 1 Introduction 1 1.1 Background . 1 1.2 Challenges in Hydrogen Measurements . 2 1.3 State of Present Hydrogen Measuring Systems . 5 1.4 Research Objective . 7 1.5 Thesis Structure . 7 2 Literature Review (Part 1): Hydrogen in Steels 8 2.1 Entry of Hydrogen into BCC Steels . 8 2.1.1 Natural Methods . 8 2.1.2 Artificial Methods . 13 2.2 Egress of Hydrogen from BCC Steels . 14 2.2.1 Natural Room Temperature . 15 2.2.2 High Temperatures . 15 2.2.3 Vacuum . 16 2.3 Classification of Hydrogen in steels . 16 2.3.1 Based on Moving Ability . 17 2.3.2 Based on Types of the Traps . 18 2.4 Hydrogen Measuring Techniques . 20 2.4.1 Overview . 20 2.5 Direct Hydrogen Measuring Techniques . 21 2.5.1 Overview . 21 2.6 Methods of Measuring Easily Mobile Hydrogen . 23 2.6.1 Overview . 23 2.6.2 Eudiometer Method . 24 2.6.3 Vacuum Foil Method . 25 2.6.4 Discussion . 25 2.7 Methods of Measuring Progressively Mobile Hydrogen . 27 2.7.1 Overview . 27 viii 2.7.2 Furnace Control Method . 27 2.7.3 Hot-Vacuum Extraction Method . 32 2.7.4 Discussion . 34 2.8 Methods of Measuring Total Hydrogen . 36 2.8.1 Overview . 36 2.8.2 Vacuum Fusion Method . 36 2.8.3 Inert Gas Fusion Method . 36 2.8.4 Tin Fusion Method . 39 2.8.5 Discussion . 42 2.9 Hydrogen Amounts in Literature . 43 2.9.1 Overview . 43 2.9.2 Amounts from Eudiometer Method . 44 2.9.3 Amounts from Hot Extraction Method . 46 3 Literature Review (Part 2): Interaction of Steels with Mercury 52 3.1 Introduction . 52 3.2 Mechanism . 53 3.3 Evidence from Industry . 54 3.4 Depth Profiles of Mercury Adsorption . 55 3.4.1 In Steel . 55 3.4.2 In Pure Iron . 56 3.5 Chemical Analysis on Contaminants . 57 3.6 Summary . 59 4 Equipment Development 62 4.1 Introduction . 62 4.2 Concept . 62 4.2.1 Selection of a Technique . 62 4.2.2 Use of Elevated Temperature . 63 4.2.3 Use of Vacuum . 64 4.3 Equipment Design . 64 4.3.1 Design Considerations . 64 4.3.2 Design Overview . 65 4.4 Materials Selection . 66 4.4.1 Overview . 66 4.4.2 Hydrogen in Stainless Steel . 69 4.4.3 Hydrogen Diffusivity . 69 4.4.4 Stainless Steel for Vacuum System . 70 4.5 Equipment Construction . 71 4.6 Stage 1: Construction of Main Components . 72 4.6.1 Vacuum Chamber . 72 4.6.2 Gaskets . 75 ix 4.6.3 Calibration Volumes . 78 4.6.4 Vacuum Pump . 80 4.6.5 Heating Mantel . 80 4.6.6 Temperature Controller . 81 4.6.7 Temperature Indicator . 81 4.6.8 Thermocouples . 82 4.6.9 Valves, Connectors and Capillaries . 82 4.6.10 Pressure Gauges . 83 4.6.11 Leak Detection System . 84 4.7 Stage 2: Initial Test Assembly . 87 4.8 Stage 3: Assembly of All Components . 89 4.8.1 Capillary Lengths . 91 4.8.2 Check for Leaks . 91 4.9 Stage 4: User Interface Panel Design and TVHS Construction . 92 4.9.1 Objective . 92 4.9.2 Panel Box Frame . 92 4.9.3 Side Panels . 92 4.9.4 Front User Interface Panel . 93 4.9.5 Final Assembly . 94 4.9.6 Wiring . 94 5 Problems Encountered and their Solutions 97 5.1 Introduction . 97 5.2 Leaking . 98 5.2.1 Issue . 98 5.2.2 Prevention of Leaks . 98 5.2.3 Preventing Vacuum Chamber Leaks . 100 5.2.4 Vacuum Leak Sealant . 102 5.2.5 Issues with Leak Detection .
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