1、Automotive Lightweighting Using Advanced High- Strength SteelsOther SAE books of interest: Dictionary of Materials and Testing, Second Edition By Joan Tomsic (Product Code: R-257) Mechanics Modeling of Sheet Metal Forming By Jwo Pan and Sing C. Tang (Product Code: R-321) Lightweight Magnesium Techno
2、logy 20012005 By Thomas Ruden (Product Code: PT-131) For more information or to order a book, contact: SAE INTERNATIONAL 400 Commonwealth Drive Warrendale, PA 15096 Phone: +1.877.606.7323 (U.S. and Canada only) or +1.724.776.4970 (outside U.S. and Canada) Fax: +1.724.776.0790 Email: CustomerServices
3、ae.org Website: books.sae.orgAutomotive Lightweighting Using Advanced High- Strength Steels By Paul Geck Warrendale, Pennsylvania USA Copyright 2014 SAE International eISBN: 978-0-7680-8129-9 400 Commonwealth Drive Warrendale, PA 15096-0001 USA E-mail: CustomerServicesae.org Phone: +1-877-606-7323 (
4、inside USA and Canada) +1-724-776-4970 (outside USA) Fax: +1-724-776-0790 Copyright 2014 SAE International. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, distributed, or transmitted, in any form or by any means without the prior written permission
5、of SAE International. For permission and licensing requests, contact SAE Permissions, 400 Commonwealth Drive, Warrendale, PA 15096-0001 USA; email: copyrightsae.org; phone: 1-724-772-4028; fax: 1-724-772-9765. SAE Order Number R-431 DOI 10.4271/R-431 Library of Congress Cataloging-in-Publication Dat
6、a Geck, Paul, 1982 Automotive lightweighting using advanced high-strength steels / by Paul Geck. pages cm Includes bibliographical references and index. ISBN 978-0-7680-7978-4 1. Steel, Automobile. 2. Lightweight steel. 3. AutomobilesMaterialsResearch. 4. AutomobilesWeight. I. Title. TL240.5.S74G43
7、2014 629.232dc23 2014006347 Information contained in this work has been obtained by SAE International from sources believed to be reliable. However, neither SAE International nor its authors guarantee the accuracy or completeness of any information published herein and neither SAE International nor
8、its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that SAE International and its authors are supplying information, but are not attempting to render engineering or other professional services.
9、If such services are required, the assistance of an appropriate professional should be sought. ISBN-Print 978-0-7680-7978-4 ISBN-PDF 978-0-7680-8129-9 ISBN-ePub 978-0-7680-8131-2 ISBN-prc 978-0-7680-8130-5 To purchase bulk quantities, please contact: SAE Customer Service Email: CustomerServicesae.or
10、g Phone: +1-877-606-7323 (inside USA and Canada) +1-724-776-4970 (outside USA) Fax: +1-724-776-0790 Visit the SAE International Bookstore at BOOKS.SAE.ORGTable of Contents Preface .vii Acknowledgments .ix Introduction .xi I.1 Scope .xi I.2 History of Advanced High-Strength Steel xi I.3 Steel Technol
11、ogy Studies . xii Chapter 1 Advanced High-Strength Steel Technology 1 1.1 Characteristics and Metallurgy .1 1.2 Drivers for Advanced High-Strength Steels7 1.3 Growth in Advanced High-Strength Steel Usage 11 1.4 Making Advanced High-Strength Steels .15 1.5 Coatings for Advanced High-Strength Steels .
12、26 1.6 References .29 Chapter 2 Impediments and Enablers for Advanced High-Strength Steels 31 2.1 Forming Advanced High-Strength Steels 31 2.2 Welding Advanced High-Strength Steels 47 2.3 Fatigue Life with Advanced High-Strength Steels .52 2.4 Stiffness Retention When Using Advanced High-Strength St
13、eels .54 2.5 Computer-Aided Engineering and Advanced High-Strength Steels 56 2.6 Variability of Advanced High-Strength Steels 58 2.7 Service and Repair of Advanced High-Strength Steels .59 2.8 References .61 Chapter 3 Example Applications of Advanced High-Strength Steels 63 3.1 Architectural Enabler
14、s for Advanced High-Strength Steels .63 3.2 IMPACT Applications 74 3.3 Body Structure Safety Application .86 3.4 Auto/Steel Partnership Closure Application 97 3.5 Reference 105 Chapter 4 Comparison of Advanced High-Strength Steels with Alternative Materials 107 4.1 Material Comparison Overview .107
15、4.2 Elementary Structural Mechanics .108 v 4.3 Generalization of Elementary Theory 111 4.4 Recent Comparisons of Advanced High-Strength Steels and Aluminum 120 4.5 Relative Costing of AHSS and Alternative Materials 134 4.6 References .143 Chapter 5 Future Direction of Advanced High-Strength Steels .
16、145 5.1 Press-Hardened Steel Applications 145 5.2 Second Generation Advanced High-Strength Steels .148 5.3 Third Generation Advanced High-Strength Steels 149 5.4 Ultimate Weight Benefits of Advanced High-Strength Steels 156 5.5 References .174 Chapter 6 Conclusions and Recommendations . 175 Index 17
17、9 About the Author 184 vi Preface In the early 1990s, as a technical specialist at Ford Motor Company, I had a small support staff working for me to put together and solve large vehicle system computer-aided engi- neering (CAE) models. Though my work was primarily focused on steel, I also did some i
18、nvestigations on alternative materials (e.g., aluminum and magnesium). It was around this period that Al Gore spearheaded the Program for Next Generation Vehicles (PNGV) during the early years of the Clinton administration. Materials research played a big part in that program, and aluminum came to t
19、he forefront as the material of the future for automobiles. Most of the material focus was on the structural body of the vehicle, and the claim was made at that time that 50% of the weight could be saved by converting steel to aluminum; mid-sized concept vehicles were built by General Motors and For
20、d to prove that claim. During the early PNGV days, through my own personal research, I came to believe that the claims for aluminum weight reduction were probably being exaggerated, but may not have been that far off, in that cars of that era had somewhat unoptimized architectures and were built out
21、 of fairly low-strength steels. The American Iron and Steel Institute (AISI) countered PNGV by building the Ultralight Steel Auto Body (ULSAB), which demonstrated that weight reductions close to what was claimed by PNGV could be achieved by extensive application of high-strength steels and accommoda
22、ting architectures. This program also introduced advanced high-strength Steels (AHSS), primarily dual-phase steels, which were used to replace some of the previous generation mild steels and conventional high-strength steel (CHSS). Though Corporate Average Fuel Economy (CAFE) requirements remained t
23、he same, during this period, the National Highway Traffic and Safety Administration (NHTSA) along with the Insurance Institute of Highway Safety (IIHS) were busy introducing new safety require- ments along with test procedures, which became de facto requirements. This, along with pending fuel econom
24、y regulations in the United States and high fuel prices in other parts of the world, prompted a number of material initiatives by the International Iron & Steel Institute (IISI) (e.g., ULSAB-AVC and Future Steel Vehicle) and by PNGV , which morphed into Freedom Car under the Bush administration. Als
25、o, by this time, Freedom Car had become more material neutral and supported some amount of steel research. Steel research was also supported by the Auto/Steel Partnership (A/SP) in the United States and internally at the auto and steel companies. Throughout this period, leading up to my retirement a
26、t the end of 2006, many materials engineers throughout the automotive industry still considered aluminum the material of the future for automobiles and still believed the weight reduction potential for aluminum to be about 45%, despite all of the steel research to the contrary. For this reason, I st
27、arted to teach a seminar at the Society of Automotive Engineers on AHSS that would lay out the true technical case for how much weight could really be taken out of automobiles, using the different material alternatives. However, I believe that the course Im teaching has hardly moved the needle for b
28、oth the alternative materials engineer and the steel engineers. As evidence of this, AHSS account for less than 10% of the steel sheet metal volume used prior vii to the time of this writing (2013). However, the automobile industry is faced with the greatest hurdle, in terms of regulation, that it h
29、as ever faced. The Environmental Protection Agency (EPA) is now requiring that automobiles achieve a fleetwide average of 54.5 MPG by 2025 through a very aggressive fuel economy phase-in program. To meet this requirement, the auto industry is taking a very hard look at alternative materials, primari
30、ly aluminum, and is accelerating the application of AHSS. Meanwhile, the steel industry is starting to market second and third generation AHHS. In support of the latest automotive challenges in terms of weight reduction, I wrote this book in an attempt to lay out the true opportunities for alternati
31、ve material utility in automo- biles and to offer the most up-to-date design guidance in efficient architectures supported with the application of AHSS while exploring weight savings and resulting fuel economy advantages of this strategy. Realistic comparisons with other alternative materials are ma
32、de through detailed analysis. Many projects that I have been part of will be explored to demon- strate how AHSS technology has developed and to get us to the foothills of the mountain that we, as automobile design people, now must climb. Paul Geck viii PrefaceAcknowledgments This was a difficult boo
33、k to write in that it covers several disciplines (e.g., automotive design engineering, computer-aided engineering, vehicle attribute engineering, metallurgy, automotive manufacturing engineering, book editing, and so on). I have strengths in some of these areas but would not be considered an expert
34、in many, especially not in metallurgy or in book editing. Therefore, I had to draw on the strengths of several colleagues. First, I would have to recognize Martha Swiss and Heather Slater of the SAE for their encouragement and editing skills. Then I would have to thank Rich Cover, who is my co-instr
35、uctor for the SAEs Advanced High-Strength Steels for Vehicle Weight Reduction class and who helped fill my metallurgy and steel-making knowledge gaps. I would also like to thank Ron Krupitzer, the vice president of automotive applications at the American Iron & Steel Institute, who helped pick a cou
36、ple of steel-automotive experts to review my manuscript as it was being developed and guided me through some of the more difficult passages. Those experts were Blake Zuidema, ArcelorMittals director of product applications, and Dean Kanelos, automotive development metallurgist at Nucor Steel. In ter
37、ms of contributions to specific sections of this book, I drew significant portions of Chapters 4 and 5 from Harjinder Singhs work as the project manager for the National Highway and Traffic Safety Administration/EDAG Inc. lightweight vehicle (LWV) study and the NanoSteel project, which was an outgro
38、wth of the LWV study. I also drew material from Jody Shaws 2013 Great Designs in Steel talk to support Chapter 4. Jody is the director of technical marketing and product research at United States Steel Corporation. I received support for many of the figures I used from Deanna Lorincz, who is the sen
39、ior director of communications for the Steel Market Development Institute. Finally, I have to thank the personnel of the NanoSteel Company (including Ellen Bossert, chief marketing officer) for supplying much of the material for Chapter 5, which points to the future of advanced high-strength steels.
40、 ix Introduction I.1 Scope This book is written with the original equipment manufacturer (OEM), Tier 1, and Tier 2 automotive design engineers in mind. However, it is hoped that many of the support people (e.g., metallurgists in both automotive and steel companies, test engineers, computer- aided en
41、gineering CAE people, materials purchasing personnel, product planners, and management) will also find this information useful. The focus will be on body and chassis structures and the sheet metal, of which these systems are primarily comprised of. More of the material addresses the automotive body,
42、 as this is where most of the advanced high- strength steels (AHSS) are being applied today. The fundamental purpose of this book is to provide information that will be useful when engineers embark on the designs of their next generation of vehicles, so that they can make informed decisions on what
43、basic materials to use and how to optimize those materials to achieve cost-effective weight reduction. Of course, in this book the emphasis will be on steels in general and AHSS in particular. However, there is much information on comparisons of steel with alternative materials for different subsyst
44、ems of the vehicle. The past, present, and future of advanced high-strength steels (AHSS) will be covered in this text as well as competing technologies such as aluminum sheet metal. Most of the material is concerned with North American applications of AHSS, because this is more familiar territory f
45、or the author, though applications of AHSS in Japan and Europe actually predated North American (NA) applications, driven by the higher fuel costs there. Given that, I have included some information on AHSS applications and studies from other parts of the world. For this book, advanced high-strength
46、 steels are defined as follows: AHSS is a family of steels having higher strength than most steels but with better form- ability than todays conventional high-strength steels. AHSS are typically multiphase steels with some percentage of martensite (the strongest of the steel phases). For our purpose
47、s, the martensitic and the hot forming steels will also be considered AHSS. For the most part, we will consider all ultra-high-strength steel as being a subset of the AHSS. I.2 History of Advanced High-Strength Steel At present, most automobiles and light trucks are approximately 70% ferrous by weig
48、ht for the whole vehicle, depending on segment. The percent of alternative material utilization has leveled off over the last few years, as it has become increasingly difficult to find new, cost-effective, alternative material applications. At the same time, new U.S. safety and fuel economy regulati
49、ons have intensified pressures at all the OEMs to seek more aggressive measures for weight reduction. These pressures are causing auto companies to rethink alter- native material applications and to look for remaining steel opportunities. In the early-1980s, the major automotive OEMs were on par in terms of weight reduction/ avoidance technologies. In the mid-1980s, some of the auto companies started to introduce xi high-strength steels (e.g., high-strength low-alloy HSLA and bake hardenable BH steels). For example, the 1986 Ford Taurus had approximately 80% mild ste
