Материаловедение : механические свойства металлов. Термическая обработка металлов. Специальные стали и сплавы
Покупка
Тематика:
Металлообработка
Издательство:
Издательский Дом НИТУ «МИСиС»
Автор:
Турилина Вероника Юрьевна
Под ред.:
Никулин Сергей Анатольевич
Год издания: 2013
Кол-во страниц: 154
Дополнительно
Вид издания:
Учебное пособие
Уровень образования:
ВО - Бакалавриат
ISBN: 978-5-87623-680-7
Артикул: 751183.01.99
Пособие содержит материал, необходимый для самостоятельной подготовки иностранных студентов к лекциям и практическим занятиям по дисциплинам «Теория и технология термической обработки металлов», «Специальные стали и сплавы», «Механические свойства металлов», «Конструкционные материалы». Рассмотрены следующие разделы: деформация, разрушение и механические свойства, фазовые и структурные превращения при нагреве и охлаждении, основные виды термической обработки, подробно рассмотрены основные виды специальных сталей и сплавов и области их применения в технике. В каждом разделе пособия приведены вопросы для самопроверки освоения материала. Этот материал даст студентам целостное представление о процессах, происходящих в сталях при термическом и деформационном воздействии, о взаимосвязи структуры и свойств, об основных принципах легирования сталей и сплавов, о способах обеспечения требуемой структуры и комплекса свойств методами термической обработки в сталях и сплавах различного назначения. Пособие предназначено для бакалавров и магистров, обучающихся по направлениям 150100 «Материаловедение и технологии материалов», 150400 «Металлургия», 011200 «Физика».
Тематика:
ББК:
УДК:
ОКСО:
- ВО - Бакалавриат
- 22.03.01: Материаловедение и технологии материалов
- 22.03.02: Металлургия
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МИНИСТЕРСТВО ОБРАЗОВАНИЯ И НАУКИ РФ ФЕДЕРАЛЬНОЕ ГОСУДАРСТВЕННОЕ АВТОНОМНОЕ ОБРАЗОВАТЕЛЬНОЕ УЧРЕЖДЕНИЕ ВЫСШЕГО ПРОФЕССИОНАЛЬНОГО ОБРАЗОВАНИЯ «НАЦИОНАЛЬНЫЙ ИССЛЕДОВАТЕЛЬСКИЙ ТЕХНОЛОГИЧЕСКИЙ УНИВЕРСИТЕТ «МИСиС» № 2138 Кафедра металловедения и физики прочности В.Ю. Турилина Материаловедение Механические свойства металлов. Термическая обработка металлов. Специальные стали и сплавы Учебное пособие Под редакцией профессора С.А. Никулина Допущено учебно-методическим объединением по образованию в области металлургии в качестве учебного пособия для студентов высших учебных заведений, обучающихся по направлению Металлургия Москва 2013
УДК 669.017 Т86 Р е ц е н з е н т д-р техн. наук, проф. С.В. Добаткин (ИМЕТ им. А.А. Байкова РАН) Турилина, В.Ю. Т86 Материаловедение : механические свойства металлов. Термическая обработка металлов. Специальные стали и сплавы : учеб. пособие / В.Ю. Турилина ; под ред. С.А. Никулина. – М. : Изд. Дом МИСиС, 2013. – 154 с. ISBN 978-5-87623-680-7 Пособие содержит материал, необходимый для самостоятельной подготовки иностранных студентов к лекциям и практическим занятиям по дисциплинам «Теория и технология термической обработки металлов», «Специальные стали и сплавы», «Механические свойства металлов», «Конструкционные материалы». Рассмотрены следующие разделы: деформация, разрушение и механические свойства; фазовые и структурные превращения при нагреве и охлаждении; основные виды термической обработки; подробно рассмотрены основные виды специальных сталей и сплавов и области их применения в технике. В каждом разделе пособия приведены вопросы для самопроверки освоения материала. Этот материал даст студентам целостное представление о процессах, происходящих в сталях при термическом и деформационном воздействии, о взаимосвязи структуры и свойств, об основных принципах легирования сталей и сплавов, о способах обеспечения требуемой структуры и комплекса свойств методами термической обработки в сталях и сплавах различного назначения. Пособие предназначено для бакалавров и магистров, обучающихся по направлениям 150100 «Материаловедение и технологии материалов», 150400 «Металлургия», 011200 «Физика». УДК 669.017 ISBN 978-5-87623-680-7 © В.Ю. Турилина, 2013
THE MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY “MISiS” № 2138 Department of Physical Metallurgy and the Physics of Strength V.Yu. Turilina Material Science Mechanical properties of metals. Heat treatment of metals. Special steels and alloys Textbook Edited by professor S.A. Nikulin Moscow 2013 MISiS PUBLISHING HOUSE
R e v i e w e r Dr. Sc., Professor S.V. Dobatkin (IMET RAN) Turilina, V.Yu. Material science : mechanical properties of metals. Heat treatment of metals. Special steels and alloys : textbook / V.Yu. Turilina ; edited S.A. Nikulin. – М. : Publishing House "MISiS", 2013. – 154 p. The textbook contains the material needed for self-training foreign students to lectures and practical classes on academic disciplines "Theory and technology of heat treatment of metals", Special Steels and Alloys", "Mechanical properties of metals", "Engineering Materials". It includes the following sections: deformation, fracture and mechanical properties, phase and structural transformations during heat treatment, the main types of heat treatment, the main types of special steels and alloys and their applications in engineering. Each section of the book contains questions for self-learning. This material will provide students with a complete picture of the processes occurring in the steel under thermal effect and deformation, the relationship of structure and properties, the basic principles of alloying steels and alloys, how to provide the required structure and properties by heat treatment in steels and alloys for various purposes. The textbook is intended for undergraduate and graduate students in areas of 150100 "Materials Science and Technology of Materials", 150400 "Metallurgy", 011200 "Physics".
CONTENTS Part 1 Mechanical properties of metals 6 1.1 Basic concepts and definitions 6 1.2 Deformation and fracture 9 1.2.1 Elastic deformation 9 1.2.2 Plastic deformation 14 1.2.3 Strengthening of metals 16 1.2.4 The fracture of materials 18 1.3 Mechanical testing of metals 28 1.3.1 Classification of mechanical tests 29 1.3.2 The main types of mechanical tests 29 Part 2 Management structure during heat treatment of steel 62 2.1 Basic concepts and definitions 62 2.2 Transformations in steel during heating and cooling 70 2.3 Heat treatment 87 2.3.1 Classification of heat treatment 87 2.3.2 First-order annealing 88 2.3.3 Second-order annealing 91 2.3.4 Hardening (quenching) 95 2.3.5 Tempering of steel 98 2.3.6 Precipitation hardening 101 2.3.7 Surface hardening 101 Part 3 Special steels and alloys 102 3.1 Ferrous alloys 105 3.1.1 General classification 106 3.1.2 Designation of steels 110 3.1.3 Constructional steels 110 3.1.4 Tool Steels 126 3.1.5 Steels with special physical properties 138 3.2 Non-ferrous alloys 147 References 153
Part 1 MECHANICAL PROPERTIES OF METALS 1.1 Basic concepts and definitions In the course of operation or use, all articles and structures are subject to the action of external forces which create internal stresses in the metal. And that is inevitably cause deformation. To keep these stresses, and, consequently, deformations within permissible limits (to prevent structural failure), it is necessary to select suitable materials for the components of various designs and to apply the most effective heat treatment. In the production of any product or design of metal is very important to know the basic characteristics of workpieces and fabricated metal product (strength, stiffness, hardness, toughness, and ductility). Mechanical properties – these are the characteristics that define the behavior of metal under the applied external forces. Mechanical properties of metals used in the manufacture of various products and designs, are determined by mechanical testing. Mechanical tests are those in which specially prepared specimens (test pieces) of standard form and size are tested on special machines. A result of mechanical testing is numerical values of mechanical properties, i.e. values of stress or strain, at which changes the physical and mechanical condition of the material. The mechanical properties are about the behavior of materials when subject to forces. When a material is subject to external forces, then internal forces are set up in the material, which oppose the external forces. The material can be considered to be rather like a spring. A spring, when stretched by external forces, sets up internal opposing forces which are readily apparent when the spring is released and they force it to contract. A material subject to external forces which stretch it is said to be in tension (Figure 1.l, a). A material subject to forces which squeeze it is said to be in compression (Figure 1.1, b). If a material is subject to forces which cause it to twist or one face slide relative to an opposite face then it is said to be in shear (Figure 1.1, c). An object, in some situations, can be subject to both tension and compression, e.g. a beam (Figure 1.2) which is being bent, the bending causing the upper surface to contract and so be in compression and the lower surface to extend and be in tension.
Figure 1.1 – Scheme of load application: a – tension; b – compression; c – shear Figure 1.2 – Scheme of load application: bending Stress and strain In discussing the application of forces to materials an important aspect is often not so much the size of the force as the force applied per unit area. Thus, for example, if we stretch a strip of material by a force P applied over its cross-sectional area F (Figure 1.3), then the force applied per unit area is F / A. Figure 1.3 – Scheme of the force applied per unit area The term stress, symbol σ, is used for the force per unit area: σ = P / F. (1.1)
Stress has the units of pascal (Pa), with 1 Pa being a force of 1 newton per square metre, i.e. 1 Pa = 1 N/m2. The stress is said to be direct stress when the area being stressed is at right angles to the line of action of the external forces, as when the material is in tension or compression. Shear stresses are not direct stresses since the forces being applied are in the same plane as the area being stressed. The area used in calculations of the stress is generally the original area that existed before the application of the forces. The stress is thus sometimes referred to as the engineering stress, the term true stress being used for the force divided by the actual area existing in the stressed state. When a material is subject to tensile or compressive forces, it changes in length (Figure 1.4). Figure 1.4 – Change in the length of the sample: a – tensile strain; b – compressive strain
The term strain, symbol ε, is used for: Strain = change in length / original length or ε = Δl / l0, (1.2) where Δl – change in length, mm; l0 – original length, mm. Since strain is a ratio of two lengths it has no units. Thus we might, for example, have a strain of 0.01. This would indicate that the change in length is 0.01 × the original length. However, strain is frequently expressed as a percentage: Strain as ε % = (change in length / original length) · 100 %. Thus the strain of 0.01 as a percentage is 1 %, i.e. this is when the change in length is 1 % of the original length. 1.2 Deformation and fracture 1.2.1 Elastic deformation Elasticity modulus Deformation is the ability of a material to change its shape and size under stress-loading. Elastic deformation is the material ability to return to its shape and size after loading is removed. If the material changes its shape after removal of loading then this kind of deformation is called plastic. Material response at elastic deformation is well described by Hooke law that determines direct proportion of stress and elastic deformation. Figure 1.5 shows elastic range of dependence “strain – stress” for such different types of deformation as tension, torsion (shear) and hydrostatic compression. Slopes of these lines characterize the E, G, K, respectively. So E is called Young’s module, G – shear module, and K – bulk (volume elasticity) module. Elasticity modules define increasing stress intensity in the process of elastic deformation. Figure 1.5 – Elasticity modulus
Elasticity modules are related with stress and strain by following equations: E = S / e, (1.3) G = t / g, (1.4) K = P / χ, (1.5) where S and t corresponds to normal and tangent stresses respectively; P – hydrostatic pressure; e and g corresponds to strains; χ – relative reduction of volume. If we consider atomic conception of elastic deformation then its mechanism is implemented in atoms reversible movements from equilibrium position in crystal lattice. An increase in atomic displacement leads to elastic deformation growth. Normally elastic deformation in metals can not be large (for example less then 0.1 % of relative elongation) because atoms are able to move reversibly just for a very small distance. Physically, elasticity module characterizes the material resistance to atoms displacement from equilibrium positions and as a result to elastic deformation, elasticity modules define stiffness of the materials. In no stress condition metal atoms oscillate near equilibrium positions in crystal lattice. Transaction forces between adjacent atoms on the one hand are made up of attraction forces between positive ions and electrons and on the other hand – repulsion forces between ions due to the electron covers deformation. Figure 1.6 shows the curves which characterize transaction forces dependence on a distance between atoms. Curve 1 corresponds to repulsion forces, curve 2 – attraction forces and 3 – outcome curve. This shows that the repulsion forces grow with the approach of atoms to each other. Naturally attraction forces smoothly decrease with the increase in the distance between atoms. Figure 1.6 – Transaction forces dependence on a distance between atoms