1、 SURFACE VEHICLE STANDARD Automotive Austempered Ductile (Nodular) Iron Castings (ADI) 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 an
2、d suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions
3、. Copyright 2004 SAE International All rights reserved. No part of this publication 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 DOCU
4、MENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS: http:/www.sae.org J2477 REV. MAY2004 Issued 2003-03 Revised 2004-05 Superseding J2477 MAR2003 1. Scope This SAE Standard covers the mechanical and physical p
5、roperty requirements for Austempered Ductile Iron (ADI) castings used in automotive and allied industries. Specifically covered are: a. Hardness b. Tensile Strength c. Yield Strength d. Elongation e. Modulus of Elasticity f. Impact Energy g. Microstructure In this document SI units are primary and i
6、n-lb units are derived. Appendix A provides general information and related resources on the microstructural, chemical and heat treatment requirements to meet the mechanical properties needed for ADI in particular service conditions and applications. 2. References 2.1 Applicable Publications The fol
7、lowing publications form a part of this specification to the extent specified herein. 2.1.1 ASTM PUBLICATIONS Available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. ASTM A 247Standard Test Method for Evaluating the Microstructure of Graphite in Iron Castings ASTM A 536Standard
8、 Specification for Ductile Iron Castings ASTM E 10Standard Test Method for Brinell Hardness of Metallic Materials ASTM E 23Standard Test Methods for Notched Bar Impact Testing of Metallic Materials ASTM E 111Standard Test Method for Youngs Modulus, Tangent Modulus and Chord Modulus SAE J2477 Revised
9、 MAY2004 - 2 - 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this specification. 2.2.1 ASM PUBLICATIONS ATTN: MSC/Book Order, ASM International, PO Box 473, Novelty, OH 44072-9901. ASM Metals Handbook, Vol. 1 Properties
10、and Selection. Iron and Steel. Ninth Edition, ASM International 1996 Materials Park, OH 44073-0002. ASM Specialty Handbook, Cast Irons. ASM International 1996 Materials Park, OH 44073-0002. 2.2.2 OTHER PUBLICATIONS 1st International Conference on Austempered Ductile Iron: Your Means to Improved Perf
11、ormance, Productivity and Cost. American Society for Metals Highway/Off-Highway Vehicles Committee Materials systems and Design Division. April 2-4, 1984 Chicago, IL. ASM International, Materials Park, OH 44073-0002. 2nd International Conference on Austempered Ductile Iron: Your Means to Improved Pe
12、rformance, Productivity and Cost. Sponsored by ASME Gear Research Institute, ASME Design Division, AMAX, Inc. March 17-19, 1986, Ann Arbor, MI. ASME Gear Research Institute c/o Pennsylvania State Univeristy, Applied Research Laboratory, P.O. Box 30, State College, PA 16804-0030. www.ductile.org/dida
13、ta Chapter IV- Austempered Ductile Iron (Ductile Iron Society (US) website) 3. Grades The specified grades, hardness and mechanical properties are shown in Table 1. TABLE 1MINIMUM MECHANICAL PROPERTIES FOR AUSTEMPERED DUCTILE IRON Grade Hardness HBN (dia. in mm) (MPa) Tensile Strength (1) (2)MPa Ten
14、sile Strength(1)(2)ksi Yield Strength(1)(2)MPa Yield Stength (1)(2)ksi % ElongationElasticity(1)(2)Modulus ofElasticity(1)(2)(3)GPa Modulus of Elasticity (1)(2)(3)psi ImpactEnergy(4)Joules ImpactEnergy(4)ft-lb AD 750 241-302 (3.90-3.50) (2360-2960) 750 110 500 70 11 148 21.5 x 106110 80 AD 900 269-3
15、41 (3.70-3.30) (2640-3340) 900 130 650 90 9 148 21.5 x 106100 75 AD1050 302-375 (3.50-3.15) (2960 -3680) 1050 150 750 110 7 148 21.5 x 10680 60 AD1200 341-444 (3.30-2.90) (3340-4350) 1200 175 850 125 4 148 21.5 x 10660 45 AD1400 388-477 (3.10-2.80) (3800-4680) 1400 200 1100 155 2 148 21.5 x 10635 25
16、 AD1600 402-512 (3.05-2.70) (3940-5020) 1600 230 1300 185 1 148 21.5 x 10620 15 1. Applied to equivalent thickness of up to 64 mm (2.5 in). For equivalent thickness greater than 64 mm (2.5 in), the mechanical properties will be mutually agreed upon by the manufacturer and the purchaser. 2. The prope
17、rty requirements in this standard are based on separately cast test bars. Casting properties and microstructure may vary due to chemistry, section size, cooling rates and other parameters. It is desired that the test bars be designed to reflect the properties of the castings they represent. The cast
18、ing process for the test bars shall be agreed upon between the manufacturer and purchaser. Refer to ASTM A 536. 3. The Youngs Modulus (E) was determined by the procedure defined in ASTM E 111. 4. Values obtained using unnotched Charpy bars tested at 22 C 2 C (72 F 4 F). The values in the table are t
19、he average of the three highest of four tested samples. For details of Charpy test refer to ASTM Impact Test (ASTM E 23). SAE J2477 Revised MAY2004 - 3 - 4. Hardness 4.1 The area or areas on the castings where hardness is to be checked shall be established by agreement between the manufacturer and p
20、urchaser. 4.2 The foundry shall exercise the necessary controls and inspection techniques to insure compliance with the specified hardness range for the application. Brinell hardness shall be determined according to ASTM E 10 Test for Brinell Hardness of Metallic Materials, after sufficient material
21、 has been removed from the casting surface to insure representative hardness readings. The 10 mm ball and 3000 kg load shall be used unless otherwise specified and agreed upon. 5. Heat treatment 5.1 Castings produced in accordance with this document shall be heat treated by an austempering process c
22、onsisting of heating the castings to a fully austenitic condition, then holding for a time sufficient to saturate the austenite with carbon, then cooling (at a rate sufficient to avoid the formation of pearlite) to a temperature above the martensite start temperature (Ms), and isothermally transform
23、ing the matrix structure for a time sufficient to produce the desired properties. This process shall produce a microstructure that is substantially ausferrite (acicular ferrite and austenite). 5.1.1 The exception to the process outlined in 5.1 is for grade AD 750. Components processed to this grade
24、may be austenitized between the upper and lower critical temperatures prior to austempering. ADI processed to this grade will exhibit a microstructure containing some pro-eutectoid ferrite with the balance being ausferrite. 5.2 Appropriate heat treatment for removal of residual stresses, or to impro
25、ve machinability shall be specified by agreement between the manufacturer and the purchaser. 5.3 Re-austempering of components or any deviation from the established heat treating process is permissible only with the expressed approval of the casting purchaser. 6. Microstructure 6.1 The graphite comp
26、onent of the microstructure shall consist of at least 85% spheroidal graphite conforming to Types I and II per ASTM A 247. 6.2 The cooling rate within some sections may not be sufficient to avoid the formation of pearlite or other high temperature transformation products. In such cases, the maximum
27、acceptable quantities of these microconstituents and the location(s) within the casting may be established by agreement between the heat treater, the manufacturer and the purchaser. 6.3 Minor amounts of martensite may be present in the microstructure of Grades 1400 and 1600. Acceptable quantities of
28、 martensite may be established by agreement between the heat treater, the manufacturer and the purchaser. 6.4 The microstructure shall be substantially free of undesirable microconstituents, the details of which are agreed upon between the heat treater, the manufacturer and the purchaser. SAE J2477
29、Revised MAY2004 - 4 - 7. Quality Assurance It is the responsibility of the manufacturer to demonstrate process capability. The specimen(s) used to do so shall be of a configuration and from a location agreed upon between the manufacturer and the purchaser. Sampling plans shall be agreed upon between
30、 the heat treater, the manufacturer and the purchaser. The manufacturer shall employ adequate controls to ensure that the parts conform to the agreed upon requirements. 8. General 8.1 Castings furnished to this standard shall be representative of good foundry practice and shall conform to dimensions
31、 and tolerances specified on the casting drawing. 8.2 Minor surface discontinuities usually not associated with the structural functioning may occur in castings. These imperfections are often repairable; however, repairs should be made only in areas and by methods approved by the purchaser. Welding
32、repair is not acceptable after Austempering. 8.3 Additional casting requirements, such as vendor identification, other casting information, and special testing, may be agreed upon by the purchaser and the supplier. These should appear as additional product requirements on the casting drawing. 9. Not
33、es 9.1 Marginal Indicia The change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions have been made to the previous issue of the report. An (R) symbol to the left of the document title indicates a complete revision of the report. PREPAR
34、ED BY THE SAE METALS TECHNICAL COMMITTEE DIVISION 9 AUTOMOTIVE IRON AND STEEL CASTINGS SAE J2477 Revised MAY2004 - 5 - APPENDIX A AUSTEMPERED DUCTILE (NODULAR) IRON (A MATERIAL DESCRIPTION NOT A PART OF THE DOCUMENT) A.1 Definition and Classification Austempered Ductile Iron (ADI) is produced by hea
35、t-treating Ductile (Nodular) Iron using the austempering Process, (as exemplified in A.5), a specialized, isothermal heat treatment. When compared to conventional ductile iron, ADI can have over twice the strength for a given level of ductility. ADI can have fatigue strength comparable to that of ca
36、st and forged steels and that strength can be greatly enhanced by subsequent grinding, fillet rolling or shot peening. Although the first commercial application of ADI did not occur until 1972, the material has found applications in virtually every industrial market segment. Its principal attribute
37、is its ability to replace steel forgings, castings and weldments at equal or lesser weight and at a reduced cost. It is also typically much less costly than aluminum and, with its high strength-to-weight ratio it has replaced cast aluminum parts at equal weight in some automotive applications. The a
38、usferrite matrix in ADI undergoes a strain transformation hardening when exposed to a high normal force. That effect makes machining of ADI challenging, but knowledge of this effect allows the machinist to adjust the feeds, speeds and tool angles to adequately compensate. This same strain transforma
39、tion hardening is what gives ADI wear resistance better than its bulk hardness would indicate. Other attributes of the material include, good noise dampening, fracture toughness and low temperature properties, and reasonable stiffness. A.2 Suggested Foundry Requirements for Ductile Iron that is to b
40、e Austempered ADI can be produced successfully from ductile iron castings with a wide range of chemistries and configurations. Although there is no optimum recipe for ADI castings, those produced to the following parameters have been shown to yield excellent results. A.2.1 Casting Quality The castin
41、gs should be free of non-metallic inclusions, carbides, shrink and dross. Proper purchasing, storage and use of charge materials will minimize the occurrence of carbides and gas defects. Proper molding control will minimize surface defects and other sub-surface discontinuities. The castings should b
42、e properly gated and poured using consistent and effective treatment and inoculation techniques to yield shrink free castings. Any of the aforementioned non-conforming conditions will reduce the “toughness” of an ADI component (even if adequate for conventional ductile). The following are recommende
43、d as a minimum: Nodule Count 100/mm2Nodularity 85% A.2.2 Carbon Equivalent The carbon equivalent (CE) can be approximated by the relationship: CE = %C + 1/3 (%Si). It should be controlled as follows in Table A1. SAE J2477 Revised MAY2004 - 6 - TABLE A1SUGGESTED CARBON EQUIVALENT RANGES FOR VARIOUS S
44、ECTION SIZES Section Size CE Range 0-13 mm (0-1/2 in) 4.4 4.6 13-51 mm ( in-2 in) 4.3 4.6 Over 51 mm (2 in) 4.3 4.5 A.2.3 Chemistry Control Good ductile iron practice should prevail for ductile iron that is to be austempered. Alloying elements such as Mo, Cu and Ni should be added only when addition
45、al hardenability is required for heavier sections. This increased “hardenability” is required only to avoid the formation of pearlite during quenching. Ultimately the amount of alloying required, (if any), will be a function of the alloys in ones base metal, the part configuration and the austemperi
46、ng process used. The proper alloy configuration should be determined jointly by the foundry and the heat-treating source. Addition of the aforementioned alloys when not required does not enhance the properties of ADI but merely adds to the cost of the iron. Composition guidelines are recommended bel
47、ow in Tables A2 and A3: TABLE A2SUGGESTED TARGETS AND CONTROL RANGES FOR INTENTIONALLY ADDED ELEMENTS Intentionally Added Elements Suggested Target Typical Control Range C Carbon 3.6% 0.20% Si Silicon 2.5% 0.20% Mg Magnesium (%S x 0.76) + 0.025% 0.005% Mn Manganese(1)0.30% 0.05% Cu Copper 0.80% maxi
48、mum (only as needed) 0.05% Ni Nickel 2.00% maximum (only as needed) 0.10% Mo Molybdenum 0.30% max. (only as needed) 0.03% 1. Up to a section size of approximately 13 mm (0.51 in), Mn targets as high as 0.60% can be used successfully. In section sizes over 13 mm (0.51 in) (or in the presence of Mo or
49、 other carbide formers) the Mn target should be reduced to 0.35% or less to minimize the formation of cell boundary carbides which may negatively affect component machinability and ductility. TABLE A3SUGGESTED MAXIMUMS AND CONTROL RANGES FOR TRACE AND TRAMP ELEMENTS Trace or Tramp Elements Suggested Target (or maximum) Typical Control Range Sn Tin 0.02% maximum 0.003% Sb Antimony 0.002% maximum 0.0003% P Phosphorus 0.04% maximum S Sulfur 0.02% maximum O Oxygen 50 ppm maximum Cr Chromium 0.10% maximum Ti Titanium 0.040
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