1、AEROSPACE MATERIAL SPECIFICATION AMS6471 REV. H Issued 1965-02 Revised 2014-07 Superseding AMS6471G Steel, Nitriding, Bars, Forgings, and Tubing 1.6Cr - 0.35Mo - 1.13Al (0.38 - 0.43C) (135 Mod) Consumable Electrode Vacuum Melted (Composition similar to UNS K24065) RATIONALE AMS6471H results from a F
2、ive Year Review and update of this specification that revises cutting restrictions, macrostructure, decarburization, and reporting requirements. 1. SCOPE 1.1 Form This specification covers a premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock
3、. 1.2 Application These products have been used typically for nitrided parts requiring high surface hardness, resistance to heat, and less distortion than parts fabricated from steel requiring quenching to case harden and subject to very rigid inspection standards, but usage is not limited to such a
4、pplications. This steel may be case hardened in dissociated ammonia gas to provide a minimum case hardness of 900 HV. 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 supplied herein. The supplie
5、r 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. 2.1 SAE Publications Available from SAE Internationa
6、l, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 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 Limits, Wrought Low-Alloy and Carbon
7、Steels _ 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 arisin
8、g therefrom, 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 2014 SAE International All rights reserved. No part of
9、 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 DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-
10、776-4970 (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:/www.sae.org/technical/standards/AMS6471H SAE INTERNATIONAL AMS6471H Page 2 of 8 AMS2300 Steel Cleanliness,
11、 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 and Low-Alloy Steel Forgings AMS2806 Identification, Bars, Wire, Mech
12、anical Tubing, and Extrusions, Carbon and Alloy Steels and Corrosion and Heat-Resistant Steels and Alloys AMS2808 Identification, Forgings AS1182 Standard Stock Removal Allowance, Aircraft-Quality and Premium Aircraft Quality Steel Bars and Mechanical Tubing 2.2 ASTM Publications Available from ASTM
13、 International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM A 255 Determining Hardenability of Steel ASTM A 370 Mechanical Testing of Steel Products ASTM A 604 Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets
14、ASTM E 112 Determining Average Grain Size ASTM E 350 Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wrought Iron ASTM E 384 Knoop and Vickers Hardness of Materials 3. TECHNICAL REQUIREMENTS 3.1 Composition Shall conform to the percentages by weight show
15、n in Table 1, determined by wet chemical methods in accordance with ASTM E 350, by spectrochemical methods, or by other analytical methods acceptable to purchaser. TABLE 1 - COMPOSITION Element min max Carbon 0.38 0.43 Manganese 0.50 0.80 Silicon 0.20 0.40 Phosphorus - 0.015 Sulfur - 0.015 Chromium
16、1.40 1.80 Molybdenum 0.30 0.40 Aluminum 0.95 1.30 Nickel - 0.25 Copper - 0.35 3.1.1 Check Analysis Composition variations shall meet the applicable requirements of AMS2259. SAE INTERNATIONAL AMS6471H Page 3 of 8 3.2 Melting Practice Steel shall be multiple melted using vacuum consumable electrode pr
17、actice in the remelt cycle. 3.3 Condition The product shall be supplied in the following condition; hardness and tensile strength shall be determined in accordance with ASTM A 370: 3.3.1 Bars 3.3.1.1 Bars 0.500 Inch (12.70 mm) and Under in Nominal Diameter or Least Distance Between Parallel Sides Co
18、ld finished having tensile strength not higher than 135 ksi (931 MPa), or equivalent hardness (See 8.2). 3.3.1.2 Bars Over 0.500 Inch (12.70 mm) in Nominal Diameter or Least Distance Between Parallel Sides Hot finished and annealed, unless otherwise ordered, having hardness not higher than 229 HB, o
19、r equivalent (See 8.3). Bars ordered cold finished may have hardness as high as 269 HB, or equivalent (See 8.3). 3.3.1.3 Bar shall not be cut from plate (Also see 4.4.2). 3.3.2 Forgings As ordered. 3.3.3 Mechanical Tubing Cold finished unless otherwise ordered, having hardness not higher than 25 HRC
20、, or equivalent (See 8.3). Tubing ordered hot finished and annealed shall have hardness not higher than 99 HRB, or equivalent (See 8.3). 3.3.4 Forging Stock As ordered by the forging manufacturer. 3.4 Properties The product shall conform to the following requirements; hardness testing shall be perfo
21、rmed in accordance with ASTM A 370: 3.4.1 Macrostructure Visual examination of transverse full cross sections from bars, billets, tube rounds, and forging stock, etched in hot hydrochloric acid in accordance with ASTM A 604, shall show no pipe or cracks. Porosity, segregation, inclusions, and other
22、imperfections shall be no worse than the macrographs of ASTM A 604 shown in Table 2. TABLE 2 - MACROSTRUCTURE LIMITS Class Condition Severity 1 Freckles A 2 White Spots A 3 Radial Segregation B 4 Ring Pattern B 3.4.2 Average Grain Size of Bars, Forgings and Tubing Shall be ASTM No. 5 or finer determ
23、ined in accordance with ASTM E 112. SAE INTERNATIONAL AMS6471H Page 4 of 8 3.4.3 Hardenability of Each Heat Shall be J 12/16 inch (19 mm) = 50 HRC minimum and J 16/16 inch (25.4 mm) = 46 HRC minimum, determined on the standard end-quench test specimen in accordance with ASTM A 255 except that the st
24、eel shall be normalized at 1800 F 10 (982 C 6) and the test specimen austenitized at 1700 F 10 (927 C 6). 3.4.4 Decarburization 3.4.4.1 Bars and tubing ordered ground, turned, or polished shall be free from decarburization on the ground, turned, or polished surfaces. Decarburization on tubing ID sha
25、ll not exceed the maximum depth specified in Table 4. 3.4.4.2 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 vendor. 3.4.4.3 Decarburization of bars to which 3.4.4.1 or
26、 3.4.4.2 is not applicable shall be not greater than shown in Table 3. TABLE 3A - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, BARS, INCH/POUND UNITS Nominal Diameter or Distance Between Parallel Sides Inches Total Depth of Decarburization Inch Up to 0.375, incl 0.015 Over 0.375 to 0.500, incl 0.017 Over
27、 0.500 to 0.625, incl 0.019 Over 0.625 to 1.000, incl 0.022 Over 1.000 to 1.500, incl 0.025 Over 1.500 to 2.000, incl 0.030 Over 2.000 to 2.500, incl 0.035 Over 2.500 to 3.000, incl 0.040 Over 3.000 to 4.000, incl 0.045 TABLE 3B - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, BARS, SI UNITS Nominal Diamet
28、er or Distance Between Parallel Sides Millimeters Total Depth of Decarburization Millimeters Up to 9.52, incl 0.38 Over 9.52 to 12.70, incl 0.43 Over 12.70 to 15.88, incl 0.48 Over 15.88 to 25.40, incl 0.56 Over 25.40 to 38.10, incl 0.64 Over 38.10 to 50.80, incl 0.76 Over 50.80 to 63.50, incl 0.89
29、Over 63.50 to 76.20, incl 1.02 Over 76.20 to 101.60, incl 1.14 3.4.4.4 Decarburization of tubing to which 3.4.4.1 or 3.4.4.2 is not applicable shall be not greater than shown in Table 4. SAE INTERNATIONAL AMS6471H Page 5 of 8 TABLE 4A MAXIMUM TOTAL DEPTH OF DECARBURIZATION, TUBING, INCH/POUND UNITS
30、Nominal Wall Thickness Inches Total Depth of Decarburization Inches ID Total Depth of Decarburization Inches OD Up to 0.109, incl 0.008 0.015 Over 0.109 to 0.203, incl 0.010 0.020 Over 0.203 to 0.400, incl 0.012 0.025 Over 0.400 to 0.600, incl 0.015 0.030 Over 0.600 to 1.000, incl 0.017 0.035 Over 1
31、.000 0.020 0.040 TABLE 4B MAXIMUM TOTAL DEPTH OF DECARBURIZATION, TUBING, SI UNITS Nominal Wall Thickness Millimeters Total Depth of Decarburization Millimeter ID Total Depth of Decarburization Millimeters OD Up to 2.77, incl 0.20 0.38 Over 2.77 to 5.16, incl 0.25 0.51 Over 5.16 to 10.16, incl 0.30
32、0.64 Over 10.16 to 15.24, incl 0.38 0.76 Over 15.24 to 25.40, incl 0.43 0.89 Over 25.40 0.51 1.02 3.4.4.5 Decarburization shall be measured by the metallographic method or by the microhardness traverse method using microhardness testing in accordance with ASTM E 384. The microhardness method shall b
33、e conducted on a hardened but untempered specimen protected during heat treatment to prevent changes in surface carbon content. Depth of decarburization, when measured by a microhardness method, is defined as the perpendicular distance from the surface to the depth under that surface where there is
34、no 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. In case of dispute, the depth of decarburization determined using the microhardness traverse method shall govern. 3.4.4.5.1 When de
35、termining the depth of decarburization, it is permissible to disregard local areas provided the decarburization of such areas does not exceed the limits of Tables 3 and 4 by more than 0.005 inch (0.13 mm) and the width is 0.065 inch (1.65 mm) or less. 3.5 Quality The product, as received by purchase
36、r, 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-quality conforming to AMS2300. 3.5.2 Bars and mechanical tubing ordered hot rolled or cold drawn or ground, turned, o
37、r polished shall, after removal of the standard stock removal allowance in accordance with AS1182, be free from seams, laps, tears, and cracks open to the machined, ground, turned, or polished surface. 3.5.3 Grain flow of die forgings, except in areas that contain flash-line end grain, shall follow
38、the general contour of the forgings showing no evidence of reentrant grain flow. 3.6 Tolerances 3.6.1 Bars In accordance with AMS2251. SAE INTERNATIONAL AMS6471H Page 6 of 8 3.6.2 Mechanical Tubing In accordance with AMS2253. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection The vend
39、or of the product shall supply all samples for vendors 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 the product conforms to specified requirements. 4.2 Classifi
40、cation of Tests 4.2.1 Acceptance Tests Composition (3.1), condition (3.3), macrostructure (3.4.1), average grain size (3.4.2), hardenability (3.4.3), decarburization (3.4.4), and tolerances (3.6) are acceptance tests and shall be performed on each heat or lot as applicable. 4.2.2 Periodic Tests Freq
41、uency-severity cleanliness rating (3.5.1) and grain flow of die forgings (3.5.3) are periodic tests and shall be performed at a frequency selected by the vendor unless frequency of testing is specified by purchaser. 4.3 Sampling and Testing 4.3.1 Bars, Mechanical Tubing, and Forging Stock In accorda
42、nce with AMS2370. 4.3.2 Forgings In accordance with AMS2372. 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 melting o
43、perations), the results of composition, macrostructure, and hardenability for each heat, and for condition and average grain size 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, AMS6471
44、H, product form and size (and/or part number, if applicable) and quantity. If forgings are supplied, the size and melt source of stock used to make the forgings shall also be included. 4.4.2 Report the nominal metallurgically worked cross sectional size and the cut size, if different (Also see 3.3.1
45、.3). 4.4.3 The producer of forging stock 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 melting operations) and the results of tests for composition, macrostructure, and hardena
46、bility of each heat. This report shall include the purchase order number, heat number, AMS6471H, size and quantity. 4.5 Resampling and Retesting 4.5.1 Bars, Mechanical Tubing, and Forging Stock In accordance with AMS2370. SAE INTERNATIONAL AMS6471H Page 7 of 8 4.5.2 Forgings In accordance with AMS23
47、72. 5. PREPARATION FOR DELIVERY 5.1 Sizes Except when exact lengths or multiples of exact lengths are ordered, straight bars and tubing will be acceptable in mill lengths of 6 to 20 feet (1.8 to 6.1 m) but not more than 10% of any shipment shall be supplied in lengths shorter than 10 feet (3 m). 5.2
48、 Identification 5.2.1 Bars and Mechanical Tubing In accordance with AMS2806. 5.2.2 Forgings In accordance with AMS2808. 5.2.3 Forging Stock As agreed upon by purchaser and vendor. 5.3 Protective Treatment Bars and tubing ordered cold drawn, cold rolled, ground, turned, or polished shall be protected
49、 from corrosion prior to shipment. 5.4 Packaging The product shall be prepared for shipment in accordance with commercial practice and in compliance with applicable rules and regulations pertaining to the handling, packaging, and transportation of the product to ensure carrier acceptance and safe delivery. 6. ACKNOWLEDGMENT A vendor shall include this specification number and its revision letter in all quotati
