1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2012 SAE International All rights reserved. No part of this pub
3、lication 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 prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970
4、(outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J401_201203SURFACEVEHICLEINFORMATIONREPORTJ401 MAR2012 Issued 1911-06Revised 2012-03
5、Superseding J401 APR2000 Selection and Use of Steels RATIONALEA five year review has uncovered several references to obsolete specifications. Those defects are rectified by this revision.1. SCOPE The SAE system of designating steels, described in SAE J402, classifies and numbers them according to ch
6、emical composition. In the case of the dent resistant, high strength and ultra high strength steels in SAE J2340, advanced high strength steels described in SAE J2745, and the high strength steels in SAE J1442 and the high-strength carbon and alloy die drawn steels in SAE J935, minimum mechanical pr
7、operty requirements have been included in the designations. In addition, hardenability data on most of the alloy steels and some of the carbon steels will be found in SAE J1268. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this specification to the extent specifie
8、d herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE J402 New Steel
9、Designation System for Wrought or Rolled Steel SAE J412 General Characteristics and Heat Treatments of Steels SAE J935 High-Strength Carbon and Alloy Die Drawn Steels SAE J1099 Technical Report on Low Cycle Fatigue Properties Ferrous and Non-Ferrous Materials SAE J1268 Hardenability Bands for Carbon
10、 and Alloy H Steels SAE J1442 High-Strength, Hot-Rolled Steel Bars SAE J401 Revised MAR2012 Page 2 of 5 SAE J2340 Categorization of Properties of Dent Resistant, High Strength, and Ultra High Strength Automotive Sheet SteelSAE J2745 Categorization and Properties of Advanced High Strength Automotive
11、Sheet Steels SAE AE-4 Fatigue Design Handbook 2.1.2 ASM Publications Available from ASM, 9639 Kinsman Road, Materials Park, OH 44073-0002, Tel: 440-338-5151, www.asminternational.org.The Selection of Steel for Metal Toughness, ASM Handbook, 9th Edition, Vol. 1, p. 403 Toughness and Fracture Mechanic
12、s, ASM Handbook, 8th Edition, Vol. 10, p. 30 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this SAE Technical Report.More detailed information on the characteristics, application and heat treatment of SAE steels is given
13、 in the SAE Information Report J412 in the SAE Handbook. References 14, 7, 8, and 10 are representative of meaningful articles that have appeared in other publications. References 5 and 9 deal with the various tests for toughness and their significance. Reference 6 details the application of linear
14、elastic fracture mechanics. Reference 11 fatigue strength and design.a. Kern, R. F., “Selection of Steels for Heat Treated Parts.” Metal Progress, Vol. 94, No. 5, November, 1968, p. 60 and No. 6, December, 1968, p. 71. b. Weymueller, C. F., “Selecting Steels for Heat Treated Auto and Truck Parts.” M
15、etal Progress, Vol. 94, No. 4, October, 1968, p. 125. c. Fox, M. M., “Saving by Substituting for Alloy Steels.” Metal Progress, Vol. 96, No. 6, December, 1969, p. 95. d. Kern, R. F., “Selecting Steels for Carburized Gears.” Metal Progress, Vol. 102, No. 1, July, 1972, p. 53. e. “The Variations in Ch
16、arpy V-notch Impact Properties in Plates.” American Iron and Steel Institute, Washington, DC, 1989.f. Barsom, J. M. and Rolfe, S. T., “Fracture and Fatigue Control in StructuresApplications of Fracture Mechanics.” 2nd Edition, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1987. g. Nagaraja Rao, N. R.,
17、Lohmann, M., and Tall, L., “Effect of Strain Rate on the Yield Stress of Structural Steels.” Journal of Materials, March, 1966. h. Barsom, J. M., “Material Considerations in Structural Steel Design.” Engineering Journal, American Institute of Steel Construction, Chicago, IL, Vol. 24, No. 3, 1987. i.
18、 Barsom, J. M., “Properties of Bridge Steels.” Vol. I, Chap. 3, Highway Structures Design Handbooks, American Institute of Steel Construction, Chicago, IL, May, 1991. SAE J401 Revised MAR2012 Page 3 of 5 j. “Commentary on Highly Restrained Welded Connections.” Engineering Journal, American Institute
19、 of Steel Construction, Third quarter, 1973. k. Signes, E. G., et al, “Factors Affecting Fatigue Strength of Welded High Strength Steels.” British Welding Journal,Vol. 14, No. 3, 1967. 3. STEEL DESIGNATION The steels so designated have been developed cooperatively by producers and users and have bee
20、n found through long experience to cover most of the wrought ferrous materials used in automotive vehicles and related equipment. Because the SAE designations provide a convenient way for engineers to state briefly but clearly the chemical composition, and in some instances, some of the properties d
21、esired, they are widely recognized and used throughout the United States and in many other countries. It should be recognized that the many technological variations of the steel-making process, coupled with the diverse requirements of the numerous processes used in the manufacture of components, mak
22、e it impossible for these brief SAE designations to completely describe any steel. A specification consists of a designation and whatever supplementary information may be necessary to describe the product desired. For this reason these designations should never be referred to as specifications, nor
23、should they be used for purchasing unless accompanied by the necessary supplementary information to describe commercially the product desired. 4. SELECTION A material for any particular use is properly selected when a part made from it satisfies the engineering and service requirements at the lowest
24、 final cost. Many factors enter into such a selection, the principal ones being: the mechanical and physical properties required to satisfy the engineering and service requirements; the cost and availability of the material; the cost of processing, such as machining, welding, or heat-treating; and t
25、he suitability of available processing equipment or the cost of new equipment that must be purchased. These considerations require input from the designer, the test engineer, the metallurgist, the manufacturing or process engineer, and the buyer. Since the pertinent factors vary widely, the correct
26、choice of material for any set of conditions is the one that provides the best balance among all the factors. Thus, a categorical selection for a given part is impractical. The successful use of different steels for similar parts is ample evidence of the complexity of the problem. 5. STATIC LOADING
27、Selection of materials is least complicated when the loading is static or the frequency of application of load during the expected life is so low that the possibility of fatigue may be neglected. In such cases, yield strength or the more precisely determined proportional limit is the strength criter
28、ion, together with a determination of the section modulus (stiffness) required to keep the stress within the elastic range. The finished structure is designed to operate only within the elastic range of its members; no part is intended to deform plastically under any reasonably expected overload. Th
29、e opposite is true in those cases where the structure is intended to provide maximum protection with minimum weight for only one major load application as in roll-over or falling object protection structures (ROPS and FOPS). Here the maximum yield strength and the section modulus are so controlled t
30、hat the structure will plastically deform under load; that is, it is the major energy absorber in the system and is an expendable item. 6. DYNAMIC LOADING When the loading is primarily dynamic (cyclic) as is the case in many automotive applications, resistance to fatigue becomes the foremost conside
31、ration. When tested as a rotating beam (R. R. Moore) specimen with a surface finish of 0.2 m (10 in) or less, the fatigue resistance of any steel, regardless of composition or condition, is more closely related to tensile strength than to any other property. For material up to about 1210 MPa (175 00
32、0 psi) the fatigue strength is about 50% of the tensile strength. For higher strength materials, this percentage decreases somewhat and the test results show increased scatter. See also SAE AE-4. SAE J401 Revised MAR2012 Page 4 of 5 The fatigue limits thus determined are seldom realized in practice
33、because few actual components are so highly finished, that is, free from surface imperfections in critical areas. If the surface of a critically stressed area is as-cast, as-forged,turned only, or decarburized, the fatigue strength may be reduced. Because they concentrate stress, undersize fillets,
34、undercuts, notches, grooves, tool marks, weld cracks, and the like are highly detrimental. Since the effect increases as tensile strength rises, an attempt to increase fatigue strength by increasing tensile strength may actually decrease component life. The remedy lies in improving the design to rem
35、ove the cause of the damaging stress concentration. If the stress concentration is caused by excessive elastic deflection under load then the best and, usually, the least expensive way to remedy the difficulty is to either increase the section modulus of the affected area or decrease that of the adj
36、acent areas, or both, the effect in either case being to reduce the deflection and the unit stress in the troubled area.This is because the elastic modulus (Youngs modulus) is, for all practical purposes, the same for all steels regardless of composition or condition. It is well established that the
37、 fatigue strength of a component can often be substantially increased by inducing compressive stresses into the outer layer in critical areas in such a way that a significant portion of the induced stress is retained after processing. In service the algebraic sum of this residual compressive stress
38、and the applied stress (usually a tensile stress from a bending or a torsional load) results in a net decrease in the stress on the component, thus increasing fatigue life. Processes commonly used to induce residual compressive stresses are shot peening, cold rolling of radii, induction hardening, s
39、hell hardening, nitriding, carbonitriding, and, sometimes, carburizing and hardening. The corollary of the previous is that any process or condition that leaves a residual tensile stress in the outer layer of a component is usually detrimental to fatigue life. SAE J1099 gives some basic information
40、on the approach to fatigue problems. The fact remains, however, that the surest guide to satisfactory fatigue resistance of a part or a structure is life testing either in actual service or under conditions thatclosely simulate it. The method is expensive, but the alternative can be a disappointing
41、lack of product reliability. 7. BRITTLE FRACTURE When improved resistance to failure by brittle fracture is of concern, toughness becomes an important additional consideration. The principal factors in determining if a material behaves in a tough or brittle manner are: (a) the type of load, static o
42、r dynamic, and its magnitude; (b) the rate of loading; (c) the stress pattern, uniaxial, biaxial, or triaxial; (d) the minimum service temperature; (e) the metallurgical history of the material, rimmed, semikilled or killed, and its microstructure, including grain size; (f) the tensile strength; and
43、 (g) the section size, rolling direction, and surface condition. In the structure in which the material is used, the presence of stress raisers of any kind from any cause will affect the behavior of the material. A detailed discussion of these factors and their interrelationship is beyond the scope
44、of this document. See 2.1.2. 8. NOTCH TOUGHNESS The most commonly used measure of toughness is the charpy V-notch (CVN) test, a single-blow impact test employing a sharply notched test bar and a high strain rate. The results are reported in footpounds (joules) absorbed in breaking the specimen or by
45、 measuring the lateral expansion at the fracture site. The test has two serious limitations: first, it is not applicable to material less than 2.5 mm (0.10 in) thick and, second, because the strain rate employed is considerably higher than that normally encountered in commercial applications of stee
46、l, the results cannot be used directly in design calculations, and it is often impossible to correlate them with service. The test is of value in two areas: first, many times, it is successfully used to compare the relative toughness of different conditions of the same steel or of different steels i
47、n any desired condition; second, it is used to determine the temperature at which the ductile-brittle transition occurs. This measure of behavior is used to provide some degree of insurance against unexpected catastrophic failure when selecting steels for low-temperature applications, provided the c
48、harpy values are related to a particular design which has been tested at the service temperature. This correlation is, perhaps, the most important use of the test, and it should, wherever and whenever possible, precede the addition of CVN requirements to a specification. SAE J401 Revised MAR2012 Pag
49、e 5 of 5 The fact remains that many machines and structures operate successfully at low temperatures without any consideration of the notch-toughness level of the material used simply because the test is so much more severe than the application that the added protection is not needed. Since the addition of a notch-toughness requirement to the material specification increases cost, failure to carefully consider the need for it can mean unne
