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Cold and Hot Forgings: Fundamentals and Applications (#05104G) © 2005 ASM International. All Rights Reserved. www.asminternational.org Cold and Hot Forgings: Fundamentals and Applications (#05104G) Cold and Hot Forging Fundamentals and Applications Edited by Taylan Altan, ERC/NSM, Ohio State University Gracious Ngaile, North Carolina State University Gangshu Shen, Ladish Company, Inc. Materials Park, Ohio 44073-0002 www.asminternational.org © 2005 ASM International. All Rights Reserved. www.asminternational.org Cold and Hot Forgings: Fundamentals and Applications (#05104G) Copyright ᭧ 2004 by ASM International௡ All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the written permission of the copyright owner. First printing, February 2005 Great care is taken in the compilation and production of this book, but it should be made clear that NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE GIVEN IN CONNECTION WITH THIS PUBLICATION. Although this information is believed to be accurate by ASM, ASM cannot guarantee that favorable results will be obtained from the use of this publication alone. This publication is intended for use by persons having technical skill, at their sole discretion and risk. Since the conditions of product or material use are outside of ASM’s control, ASM assumes no liability or obligation in connection with any use of this information. No claim of any kind, whether as to products or information in this publication, and whether or not based on negligence, shall be greater in amount than the purchase price of this product or publication in respect of which damages are claimed. THE REMEDY HEREBY PROVIDED SHALL BE THE EXCLUSIVE AND SOLE REMEDY OF BUYER, AND IN NO EVENT SHALL EITHER PARTY BE LIABLE FOR SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES WHETHER OR NOT CAUSED BY OR RESULTING FROM THE NEGLIGENCE OF SUCH PARTY. As with any material, evaluation of the material under end-use conditions prior to specification is essential. Therefore, specific testing under actual conditions is recommended. Nothing contained in this book shall be construed as a grant of any right of manufacture, sale, use, or reproduction, in connection with any method, process, apparatus, product, composition, or system, whether or not covered by letters patent, copyright, or trademark, and nothing con- tained in this book shall be construed as a defense against any alleged infringement of letters patent, copyright, or trademark, or as a defense against liability for such infringement. Comments, criticisms, and suggestions are invited, and should be forwarded to ASM Interna- tional. Prepared under the direction of the ASM International Technical Books Committee (2004–2005), Yip-Wah Chung, FASM, Chair. ASM International staff who worked on this project include Scott Henry, Senior Manager of Product and Service Development; Bonnie Sanders, Manager of Production; Carol Polakowski, Production Supervisor; and Pattie Pace, Production Coordinator. Library of Congress Cataloging-in-Publication Data Cold and hot forging : fundamentals and applications / edited by Taylan Altan, Gracious Ngaile, Gangshu Shen. p. cm. Includes bibliographical references and index. ISBN: 0-87170-805-1 1. Forging. I. Altan, Taylan. II. Ngaile, Gracious. III. Shen, Gangshu. TS225.C63 2004 671.3Ј32—dc22 2004055439 SAN: 204-7586 ASM International௡ Materials Park, OH 44073-0002 www.asminternational.org Printed in the United States of America © 2005 ASM International. All Rights Reserved. www.asminternational.org Cold and Hot Forgings: Fundamentals and Applications (#05104G) Contents Preface ..............................................................................................viii Chapter 1 Metal Forming Processes in Manufacturing ...........................1 1.1 Classification of Manufacturing Processes .......................................1 1.2 Characteristics of Manufacturing Processes ......................................2 1.3 Metal Forming Processes in Manufacturing ......................................4 Chapter 2 Forging Processes: Variables and Descriptions .......................7 2.1 Introduction ...............................................................................7 2.2 Forging Operation as a System ......................................................7 2.3 Types of Forging Processes ...........................................................9 Chapter 3 Plastic Deformation: Strain and Strain Rate ........................ 17 3.1 Introduction ............................................................................. 17 3.2 Stress Tensor ............................................................................ 17 3.3 Properties of the Stress Tensor ..................................................... 18 3.4 Plane Stress or Biaxial Stress Condition ........................................ 19 3.5 Local Deformations and the Velocity Field .................................... 20 3.6 Strains ..................................................................................... 20 3.7 Velocities and Strain Rates .......................................................... 21 3.8 Homogeneous Deformation ......................................................... 21 3.9 Plastic (True) Strain and Engineering Strain ................................... 23 Chapter 4 Flow Stress and Forgeability .............................................. 25 4.1 Introduction ............................................................................. 25 4.2 Tensile Test .............................................................................. 27 4.3 Compression Test ...................................................................... 29 4.4 Ring Test ................................................................................. 35 4.5 Torsion Test ............................................................................. 36 4.6 Representation of Flow Stress Data .............................................. 36 Appendices (CD-ROM only) 4.1 Determination of Flow Stress by Compression Test at Room Temperature 4.2 Determination of Flow Stress at High Temperature 4.3 Forgeability and Damage Factor in Cold Forging © 2005 ASM International. All Rights Reserved. www.asminternational.org Cold and Hot Forgings: Fundamentals and Applications (#05104G) iv / Cold and Hot Forging: Fundamentals and Applications Chapter 5 Plastic Deformation: Complex State of Stress and Flow Rules ....................................................................... 51 5.1 State of Stress ........................................................................... 51 5.2 Yield Criteria ............................................................................ 52 5.3 Flow Rules .............................................................................. 55 5.4 Power and Energy of Deformation ............................................... 56 5.5 Effective Strain and Effective Strain Rate ...................................... 57 Chapter 6 Temperatures and Heat Transfer ........................................ 59 6.1 Introduction ............................................................................. 59 6.2 Heat Generation and Heat Transfer in Metal Forming Processes ........ 59 6.3 Temperatures in Forging Operations ............................................. 60 6.4 Measurement of Temperatures at the Die/Material Interface .............. 60 6.5 Measurement of Interface Heat Transfer Coefficient ........................ 62 6.6 Influence of Press Speed and Contact Time on Heat Transfer ............ 64 Appendices (CD-ROM only) 6.1 Upset Forging of Cylinders Chapter 7 Friction and Lubrication ................................................... 67 7.1 Introduction ............................................................................. 67 7.2 Lubrication Mechanisms in Metal Forming .................................... 68 7.3 Friction Laws and Their Validity in Forging ................................... 69 7.4 Parameters Influencing Friction and Lubrication ............................. 69 7.5 Characteristics of Lubricants Used ............................................... 70 7.6 Lubrication Systems for Cold Forging .......................................... 70 7.7 Lubrication Systems for Warm and Hot Forging ............................. 73 7.8 Methods for Evaluation of Lubricants ........................................... 74 Appendices (CD-ROM only) 7.1 Ring Compression Test 7.2 Double Cup Extrusion Test Chapter 8 Inverse Analysis for Simultaneous Determination of Flow Stress and Friction .................................................... 83 8.1 Introduction ............................................................................. 83 8.2 Inverse Analysis in Metal Forming ............................................... 83 8.3 Flow Stress Determination in Forging by Inverse Analysis ............... 85 8.4 Inverse Analysis for Simultaneous Determination of Flow Stress and Friction .............................................................................. 86 8.5 Example of Inverse Analysis ....................................................... 86 Chapter 9 Methods of Analysis for Forging Operations ........................ 91 9.1 Introduction ............................................................................. 91 9.2 Slab Method of Analysis ...........................................................
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