Lecture

Steel Heat Treatment: Transformation Diagrams

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In course

MSE-234: Mechanical behaviour of materials

Ce cours est une introduction au comportement mécanique, à l'élaboration, à la structure et au cycle de vie des grandes classes de matériaux de structure (métaux, polymères, céramiques et composites) ...

Description

This lecture covers the transformation diagrams of steel, focusing on the TTT diagram for eutectoid and hypoeutectoid steels, the concept of austenitization, the formation of martensite, bainite, and perlite, and the effects of alloying elements on the transformation process. It also discusses the hardenability of steels, the tempering of martensite, and the secondary hardening phenomenon. Additionally, it explores the importance of isothermal treatments, surface treatments like carburization and nitriding, and the challenges of temper embrittlement. The lecture concludes with a detailed explanation of the tempering process of martensite and the critical role of carbon migration in stabilizing the microstructure.

Instructors (3)

Andreas Mortensen

Andreas Mortensen is currently Professor and Director of the Institute of Materials at the Swiss Federal Institute of Technology in Lausanne (EPFL), where he heads the Laboratory for Mechanical Metallurgy. He joined the faculty of EPFL 1997 after ten years, from 1986 to 1996, as a member of the faculty of the Department of Materials Science and Engineering at the Massachusetts Institute of Technology, where he held the successive titles of ALCOA Assistant Professor, Associate Professor, and Professor. His research is focussed on the processing, microstructural development and mechanical behavior of advanced metallic materials with particular focus on metal matrix composites and metal foams, on infiltration processing and capillarity, and on damage and fracture in metallic materials. He is author or co-author of two monographs, around one hundred and eighty scientific or technical publications and twelve patents. Born in San Francisco in 1957, of dual (Danish and US) nationality, Andreas Mortensen graduated in 1980 from the Ecole Nationale Supérieure des Mines de Paris with a Diplôme dIngénieur Civil, and earned his Ph.D. in the Department of Materials Science and Engineering at MIT in 1986. Besides his academic employment, he was a postdoctoral researcher at Nippon Steel during part of 1986, and was invited professor at the Ecole des Mines in Paris during the academic year 1995 to 1996. He is a member of the editorial committee of International Materials Reviews and has co-edited four books. He is a Fellow of ASM, a recipient of the Howe Medal and the Grossman Award of the American Society of Metals, was awarded the Péchiney Prize by the French Academy of Sciences and the Res Metallica Chair from the Katholieke Universiteit Leuven, received three EPFL teaching awards, is one of ISIs Highly Cited authors for Materials Science since 2002 and was awarded an ERC advanced grant in 2012.

David Hernandez Escobar

Expertise Physical metallurgy, ceramics, micro-mechanical testing Education Ph.D. Materials Science and Engineering | 2016 – 2021 Michigan State University B.S. Materials Engineering | 2012 – 2016 Universidad Politécnica de Madrid

Julie Nathalie S Gheysen

Professionals experiences PhD student 2018–2022 Université Catholique de Louvain Teaching & PhD Courses Materials MSE-171 Introduction course of material science applied to usual building materials, especially concrete and metals. Description of their fabrication, mechanical and thermal properties and use in construction. Mechanical behaviour of materials MSE-234 This course provides an introduction to the mechanical behaviour, the processing, the structure and life-cycle o

Official source

Ontological neighbourhood

Chemical engineering

Materials science: Alloys

Related concepts (32)

Tempering (metallurgy)

Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product.

Carbon steel

Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: no minimum content is specified or required for chromium, cobalt, molybdenum, nickel, niobium, titanium, tungsten, vanadium, zirconium, or any other element to be added to obtain a desired alloying effect; the specified minimum for copper does not exceed 0.40%; or the specified maximum for any of the following elements does not exceed the percentages noted: manganese 1.

Steel

Steel is an alloy of iron and carbon with improved strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels, which are resistant to corrosion and oxidation, typically need an additional 11% chromium. Because of its high tensile strength and low cost, steel is used in buildings, infrastructure, tools, ships, trains, cars, bicycles, machines, electrical appliances, furniture, and weapons. Iron is the base metal of steel.

Stainless steel

Stainless steel, also known as inox or corrosion-resistant steel (CRES), is an alloy of iron that is resistant to rusting and corrosion. It contains at least 10.5% chromium and usually nickel, and may also contain other elements, such as carbon, to obtain the desired properties. Stainless steel's resistance to corrosion results from the chromium, which forms a passive film that can protect the material and self-heal in the presence of oxygen. The alloy's properties, such as luster and resistance to corrosion, are useful in many applications.

Bainite

Bainite is a plate-like microstructure that forms in steels at temperatures of 125–550 °C (depending on alloy content). First described by E. S. Davenport and Edgar Bain, it is one of the products that may form when austenite (the face-centered cubic crystal structure of iron) is cooled past a temperature where it is no longer thermodynamically stable with respect to ferrite, cementite, or ferrite and cementite. Davenport and Bain originally described the microstructure as being similar in appearance to tempered martensite.

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