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 ther
2、efrom, 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 2017 SAE International All rights reserved. No part of this
3、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 DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-49
4、70 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/AMS6481D AEROSPACE MATERIAL SPECIFICATION AMS6481 REV. D Issued 1998-10 Reaffirmed 2006-04 Rev
5、ised 2017-04 Superseding AMS6481C Steel Bars, Forgings, and Tubing, Nitriding 3Cr - 1Mo - 0.2V - (0.29 - 0.36C) Premium Aircraft-Quality for Bearing Applications Double Vacuum Melted (Composition similar to UNS K24340) RATIONALE AMS6481D results from a Five-Year Review and update of this specificati
6、on that revises micro-inclusion testing (3.4.2.1), the test procedure for decarburization (3.4.5.5), quality (3.5), and reporting (4.4). 1. SCOPE 1.1 Form This specification covers a nitriding grade of premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and fo
7、rging stock. 1.2 Application These products have been used typically for nitrided parts such as bearings, operating under heavy loads and high speeds at moderate temperatures, and subject to very rigid inspection standards, and requiring highest surface hardness, high core toughness, and less distor
8、tion than parts made from steel requiring quenching to case harden, but usage is not limited to such applications. 2. APPLICABLE DOCUMENTS The issue of the following documents in effect on the date of the purchase order forms a part of this specification to the extent specified herein. The supplier
9、may work to a subsequent revision of a document unless a specific document issue is specified. When the referenced document has been cancelled and no superseding document has been specified, the last published issue of that document shall apply. SAE INTERNATIONAL AMS6481D Page 2 of 9 2.1 SAE Publica
10、tions Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org. AMS2251 Tolerances Low-Alloy Steel Bars AMS2253 Tolerances Carbon and Alloy Steel Tubing AMS2259 Chemical Check Analysis
11、 Limits Wrought Low-Alloy and Carbon Steels AMS2300 Steel Cleanliness, Premium Aircraft-Quality Magnetic Particle Inspection Procedure AMS2370 Quality Assurance Sampling and Testing Carbon and Low-Alloy Steel Wrought Products and Forging Stock AMS2372 Quality Assurance Sampling and Testing Carbon an
12、d Low-Alloy Steel Forgings AMS2806 Identification Bars, Wire, Mechanical Tubing, and Extrusions Carbon and Alloy Steels and Corrosion and Heat-Resistant Steels and Alloys AMS2808 Identification Forgings ARP1917 Clarification of Terms Used in Aerospace Metals Specifications AS1182 Standard Stock Remo
13、val Allowance Aircraft-Quality and Premium Aircraft-Quality Steel Bars and Mechanical Tubing 2.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM A370 Mechanical Testing of Steel Product
14、s ASTM A604 Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets ASTM E45 Determining the Inclusion Content of Steels ASTM E112 Determining Average Grain Size ASTM E140 Hardness Conversion Tables for MetalsHardness Conversion Tables for Metals Relationship Among Brinell Hardness
15、, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness ASTM E350 Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wrought Iron ASTM E384 Microindentation Hardness of Materials SAE INTERNATIONAL
16、 AMS6481D Page 3 of 9 3. TECHNICAL REQUIREMENTS 3.1 Composition Shall conform to the following percentages by weight shown in Table 1, determined by wet chemical methods in accordance with ASTM E350 or by spectrochemical or other analytical methods acceptable to purchaser. Table 1 - Composition Elem
17、ent Min Max Carbon 0.29 0.36 Manganese 0.40 0.70 Silicon 0.10 0.40 Phosphorus - 0.015 Sulfur - 0.005 Chromium 2.80 3.30 Nickel - 0.30 Molybdenum 0.70 1.20 Vanadium 0.15 0.35 Copper - 0.10 3.1.1 Check Analysis Composition variations shall meet the applicable requirements of AMS2259. 3.2 Melting Pract
18、ice Steel shall be double vacuum melted, using vacuum induction melting followed by vacuum arc consumable electrode remelting. 3.3 Condition The product shall be supplied in the following condition; hardness and tensile strength shall be determined in accordance with ASTM A370: 3.3.1 Bars Bar shall
19、not be cut from plate (also see 4.4.2). 3.3.1.1 Bars 0.500 Inch (12.70 mm) and Under in Nominal Diameter or Least Distance Between Parallel Sides Cold finished having tensile strength not higher than 125 ksi (862 MPa) or equivalent hardness (see 8.2). 3.3.1.2 Bars over 0.500 Inch (12.70 mm) in Nomin
20、al Diameter or Least Distance Between Parallel Sides Hot finished and annealed, unless otherwise ordered, having hardness not higher than 255 HBW, or equivalent (see 8.3). Bars ordered cold finished may have hardness as high as 269 HBW or equivalent (see 8.3). 3.3.2 Forgings As ordered. 3.3.3 Mechan
21、ical Tubing Cold finished, unless otherwise ordered, having hardness not higher than 272 HBW, or equivalent (see 8.3). Tubing ordered hot finished and annealed shall have hardness not higher than 248 HBW or equivalent (see 8.3). SAE INTERNATIONAL AMS6481D Page 4 of 9 3.3.4 Forging Stock As ordered b
22、y the forging manufacturer. 3.4 Properties The product shall conform to the following requirements; mechanical tests shall be performed in accordance with ASTM A370: 3.4.1 Macrostructure Visual examination of transverse full cross-sections from bars, billets, tube rounds (solid, not hollow), or forg
23、ing stock, etched in hot hydrochloric acid in accordance with ASTM A604, shall show no pipe or cracks. Porosity, segregation, inclusions, and other imperfections shall be no worse than the macrographs of ASTM A604 shown in Table 2. Table 2 - Macrostructure Class Condition Severity 1 Freckles A 2 Whi
24、te Spots A 3 Radial Segregation B 4 Ring Pattern B 3.4.1.1 Macrostructure examination is not required for hollow tubes that are produced directly from ingots or blooms unless specified by purchaser, in which case the purchaser shall specify standards to be used. 3.4.2 Micro-Inclusion Rating of Each
25、Heat No specimen shall exceed the limits shown in Table 3, determined in accordance with ASTM E45, Method D. Table 3 - Micro-inclusion rating limits Type A Thin A Heavy B Thin B Heavy C Thin C Heavy D Thin D Heavy Worst Field Severity 1.5 1.0 1.0 1.0 1.0 1.0 1.5 1.0 Worst Field Frequency, maximum a1
26、 a1 a1 3 1 Total Rateable Fields, Frequency, maximum b1 b1 b1 5 1 a -Combined A+B+C, not more than 3 fields b - Combined A+B+C, not more than 8 fields 3.4.2.1 A rateable field is defined as one which has a type A, B, C, or D inclusion rating of at least No. 1.0 thin or heavy in accordance ASTM E45.
27、3.4.3 Average Grain Size of Bars, Forgings, and Tubing Shall be ASTM No. 6 or finer determined in accordance with ASTM E112. 3.4.4 Response to Heat Treatment of Bars, Forgings, Tubing, and Forging Stock The product (see 4.3.3) shall have the properties shown in Table 4 after being austenitized by he
28、ating to 1690 F 15 F (921 C 10 C), holding 1 to 3 hours, and quenching in oil, followed by tempering for 2 hours minimum at not lower than 1110 F (599 C). SAE INTERNATIONAL AMS6481D Page 5 of 9 Table 4 - Longitudinal mechanical properties Property Value Tensile Strength, min 165 ksi (1138 MPa) Yield
29、 Strength 0.2%, min 138 ksi ( 951 MPa) Elongation in 4D, min 13% Charpy V-notch, min 50 ft-lb (68 J) Hardness 352 to 388 HBW, or equivalent (see 8.3) 3.4.5 Decarburization 3.4.5.1 Bars and tubing ordered ground, turned, or polished shall be free from decarburization on the ground, turned, or polishe
30、d surfaces. Decarburization on tubing ID shall not exceed the maximum depth specified in Table 6. 3.4.5.2 Allowable decarburization of bars, billets, and tube rounds ordered for redrawing or forging or to specified microstructural requirements shall be as agreed upon by purchaser and producer. 3.4.5
31、.3 Decarburization of bars that 3.4.5.1 or 3.4.5.2 is not applicable shall be not greater than shown in Table 5. Table 5 Table 5A - Maximum depth of decarburization, inch/pound units Nominal Diameter or Distance Between Parallel Sides Inches Total Depth of Decarburization Inch Up to 0.500, incl 0.01
32、5 Over 0.500 to 1.000, incl 0.030 Over 1.000 to 2.000, incl 0.040 Over 2.000 to 3.000, incl 0.050 Over 3.000 to 4.000, incl 0.065 Over 4.000 to 5.000, incl 0.095 Table 5B - Maximum depth of decarburization, SI units Nominal Diameter or Distance Between Parallel Sides Millimeters Total Depth of Decar
33、burization Millimeters Up to 12.70, incl 0.38 Over 12.70 to 25.40, incl 0.76 Over 25.40 to 50.80, incl 1.02 Over 50.80 to 75,20, incl 1.27 Over 75.20 to 101.60, incl 1.65 Over 101.60 to 127.00, incl 2.41 3.4.5.4 Decarburization of tubing that 3.4.5.1 or 3.4.5.2 is not applicable shall be not greater
34、 than shown in Table 6. Table 6 Table 6A - Maximum depth of decarburization, inch/pound units Nominal Outside Diameter Inches Total Depth of Decarburization Inch Up to 1.000, incl 0.025 Over 1.000 to 2.000, incl 0.035 Over 2.000 to 3.000, incl 0.045 Over 3.000 to 4.000, incl 0.055 Over 4.000 to 5.00
35、0, incl 0.080 SAE INTERNATIONAL AMS6481D Page 6 of 9 Table 6B - Maximum depth of decarburization, SI units Nominal Outside Diameter Millimeters Total Depth of Decarburization Millimeters Up to 25.40, incl 0.64 Over 25.40 to 50.80, incl 0.89 Over 50.80 to 75.20, incl 1.14 Over 75.20 to 101.60, incl 1
36、.40 Over 101.60 to 127.00, incl 2.03 3.4.5.5 Decarburization shall be evaluated by one of the two methods of 3.4.5.5.1 or 3.4.5.5.2. 3.4.5.5.1 Metallographic Method A cross section taken perpendicular to the surface shall be prepared, etched, and visually examined metallographically at a magnificati
37、on not to exceed 100X. Optical indications of decarburiztion shall not show a layer of complete (ferrite) or partial decarburization exceeding the limits of Tables 5 or 6. 3.4.5.5.2 Hardness Traverse Method The total depth of decarburization shall be determined by a traverse method using microindent
38、ation hardness testing in accordance with ASTM E384, at a magnification not exceeding 100X, conducted on a hardened, but untempered specimen, protected during heat treatment to prevent changes in surface carbon content. Depth of decarburization is defined as the perpendicular distance from the surfa
39、ce to the depth under that surface where there is not further increase in hardness. Such measurements shall be far enough away from any adjacent surface to be uninfluenced by any decarburization on the adjacent surface. Acceptance shall be as listed in Tables 5 or 6. 3.4.5.6 When determining the dep
40、th of decarburization, it is permissible to disregard local areas provided the decarburization of such areas does not exceed the above limits by more than 0.005 inch (0.13 mm) and the width is 0.065 inch (1.65 mm) or less. 3.4.5.7 In case of dispute, the total depth of decarburization determined usi
41、ng the microindentation hardness traverse method shall govern. 3.5 Quality The product, as received by purchaser, shall be uniform in quality and condition, sound, and free from foreign materials and from imperfections detrimental to usage of the product. 3.5.1 Steel shall be premium aircraft-qualit
42、y conforming to AMS2300. 3.5.2 Bars and mechanical tubing shall be free from seams, laps, tears, and cracks after removal of the standard machining allowance in accordance with AS1182. 3.5.3 Grain flow of die forgings, except in areas which contain flash-line end grain, shall follow the general cont
43、our of the forgings showing no evidence of reentrant grain flow. 3.6 Tolerances 3.6.1 Bars In accordance with AMS2251. 3.6.2 Mechanical Tubing In accordance with AMS2253. SAE INTERNATIONAL AMS6481D Page 7 of 9 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection The producer of the prod
44、uct shall supply all samples for producers tests and shall be responsible for the performance of all required tests. Purchaser reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that product conforms to specified requirements. 4.2 Classification of Tests
45、4.2.1 Acceptance Tests Composition (3.1), condition (3.3), macrostructure (3.4.1), micro-inclusion rating (3.4.2), average grain size (3.4.3), response to heat treatment (3.4.4), decarburization (3.4.5) and tolerances (3.6) are acceptance tests and shall be performed on each heat or lot as applicabl
46、e. 4.2.2 Periodic Tests Frequency severity rating (3.5.1) and grain flow of die forgings (3.5.2) are periodic tests and shall be performed at a frequency selected by the producer unless frequency of testing is specified by purchaser. 4.3 Sampling and Testing 4.3.1 Bars, Mechanical Tubing, and Forgin
47、g Stock In accordance with AMS2370. 4.3.2 Forgings In accordance with AMS2372. 4.3.3 Samples for Response to Heat Treatment Samples shall be extracted from the full cross section of the product, except that product over 2 inches (50.8 mm) in nominal diameter, or least distance between parallel sides
48、 may be forged or machined to 2 inches (50.8 mm) before testing. 4.4 Reports 4.4.1 The producer of bars, forgings, and tubing shall furnish with each shipment a report showing the producer identity, country where the metal was melted (e.g., final melt in the case of metal processed by multiple melti
49、ng operations), results of tests for composition, macrostructure, and micro-inclusion rating of each heat and for average grain size and response to heat treatment, including the tempering temperature used, of each lot, and stating that the product conforms to the other technical requirements. This report shall include the purchase order number, heat and lot numbers, AMS6481D, product form and size (and/or
