1、AEROSPACE MATERIAL SPECIFICATION AMS6470 REV. N Issued 1939-12 Revised 2014-07 Superseding AMS6470M Steel, Nitriding, Bars, Forgings, and Tubing 1.6Cr - 0.35Mo - 1.13Al (0.38 - 0.43C) (135 Mod) (Composition similar to UNS K24065) RATIONALE AMS6470N results from a Five Year Review and update of this
2、specification that revises cutting restrictions macrostructure, decarburization, and reporting requirements. 1. SCOPE 1.1 Form This specification covers an aircraft-quality nitriding grade low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock. 1.2 Application These prod
3、ucts 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, but usage is not limited to such applications. This steel may be case hardened in dissociated ammonia gas to
4、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 specified herein. The supplier may work to a subsequent revision of a document unless a specific docume
5、nt 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 International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (i
6、nside 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 Steels AMS2301 Steel Cleanliness, Aircraft Quality, Magnetic Particle Insp
7、ection Procedure _ 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 infringem
8、ent 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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved.
9、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 DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Te
10、l: +1 724-776-4970 (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/AMS6470N SAE INTERNATIONAL AMS6470N Page 2 of 8 AMS2370 Quality
11、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, Mechanical Tubing, and Extrusions, Carbon and Alloy Steels and Corrosion and Heat-Resi
12、stant 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 International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-
13、2959, Tel: 610-832-9585, www.astm.org. ASTM A 255 Determining Hardenability of Steel ASTM A 370 Mechanical Testing of Steel Products 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
14、381 Macroetch Testing Steel Bars, Billets, Blooms, and Forgings ASTM E 384 Knoop and Vickers Hardness of Materials 3. TECHNICAL REQUIREMENTS 3.1 Composition Shall conform to the percentages by weight shown in Table 1, determined by wet chemical methods in accordance with ASTM E 350, by spectrochemic
15、al 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 - 0.025 Sulfur - 0.025 Chromium 1.40 1.80 Molybdenum 0.30 0.40 Aluminum 0.95 1.30 Nickel - 0.25 Copper - 0.35 3.1.1 Check Analys
16、is Composition variations shall meet the applicable requirements of AMS2259. SAE INTERNATIONAL AMS6470N Page 3 of 8 3.2 Condition The product shall be supplied in the following condition; hardness and tensile strength shall be determined in accordance with ASTM A 370: 3.2.1 Bars 3.2.1.1 Bars 0.500 I
17、nch (12.70 mm) and Under in Nominal Diameter or Least Distance Between Parallel Sides Cold finished having tensile strength not higher than 135 ksi (931 MPa), or equivalent hardness (See 8.2). 3.2.1.2 Bars Over 0.500 Inch (12.70 mm) in Nominal Diameter or Least Distance Between Parallel Sides Hot fi
18、nished and annealed, unless otherwise ordered, having hardness not higher than 229 HB, or equivalent (See 8.3). Bars ordered cold finished may have hardness as high as 269 HB, or equivalent (See 8.3). 3.2.1.3 Bar shall not be cut from plate (Also see 4.4.2). 3.2.2 Forgings As ordered. 3.2.3 Mechanic
19、al Tubing Cold finished, unless otherwise ordered, having hardness not higher than 25 HRC, or equivalent (See 8.3). Tubing ordered hot finished and annealed shall have hardness not higher than 99 HRB, or equivalent (See 8.3). 3.2.4 Forging Stock As ordered by the forging manufacturer. 3.3 Properties
20、 The product shall conform to the following requirements; hardness testing shall be performed in accordance with ASTM A 370: 3.3.1 Macrostructure Visual examination of transverse full cross-sections from bars, billets, tube rounds and forging stock, etched in hot hydrochloric acid in accordance with
21、 ASTM E 381, shall show no pipe or cracks. Porosity, segregation, inclusions, and other imperfections shall be no worse than the macrographs of ASTM E 381 shown in Table 2. TABLE 2 - MACROSTRUCTURE LIMITS Cross-Sectional Area Square Inches Cross-Sectional Area Square Centimeters Macrographs Up to 36
22、, incl Up to 232, incl S2 - R1 - C2 Over 36 to 133, incl Over 232 to 858, incl S2 - R2 - C3 Over 133 Over 858 Note 1 Note 1: Limits for larger sizes shall be agreed upon by purchaser and vendor. The purchaser shall have written approval from the cognizant engineering organization. 3.3.2 Average Grai
23、n Size of Bars, Forgings and Tubing Shall be ASTM No. 5 or finer determined in accordance with ASTM E 112. SAE INTERNATIONAL AMS6470N Page 4 of 8 3.3.3 Hardenability of Each Heat Shall be J8/16 inch (12.7 mm) = 50 HRC minimum and J12/16 inch (19 mm) = 45 HRC minimum, determined on the standard end-q
24、uench test specimen in accordance with ASTM A 255 except that the steel shall be normalized at 1800 F 10 (982 C 6) and the test specimen austenitized at 1700 F 10 (927 C 6). 3.3.4 Decarburization 3.3.4.1 Bars and tubing ordered ground, turned, or polished shall be free from decarburization on the gr
25、ound, turned, or polished surfaces. Decarburization on tubing ID shall not exceed the maximum depth specified in Table 4. 3.3.4.2 Allowable decarburization of bars, billets, and tube rounds ordered for redrawing or forging or to specified microstructural requirements shall be as agreed upon by purch
26、aser and vendor. 3.3.4.3 Decarburization of bars to which 3.3.4.1 or 3.3.4.2 is not applicable shall be not greater than shown in Table 3. TABLE 3A - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, INCH/POUND UNITS Nominal Diameter or Distance Between Parallel Sides Inches Total Depth of Decarburization Inc
27、h Up to 0.500, incl 0.030 Over 0.500 to 1.000, incl 0.035 Over 1.000 to 1.500, incl 0.040 Over 1.500 to 2.000, incl 0.050 Over 2.000 to 2.500, incl 0.060 Over 2.500 to 3.000, incl 0.070 TABLE 3B - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, SI UNITS Nominal Diameter or Distance Between Parallel Sides Mi
28、llimeters Total Depth of Decarburization Millimeters Up to 12.70, incl 0.76 Over 12.70 to 25.40, incl 0.89 Over 25.40 to 38.10, incl 1.02 Over 38.10 to 50.80, incl 1.27 Over 50.80 to 63.50, incl 1.52 Over 63.50 to 76.20, incl 1.78 3.3.4.4 Decarburization of tubing to which 3.3.4.1 or 3.3.4.2 is not
29、applicable shall be not greater than shown in Table 4. TABLE 4A - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, INCH/POUND UNITS Nominal Wall Thickness Inches Total Depth of Decarburization Inch ID Total Depth of Decarburization Inch OD Up to 0.109, incl 0.008 0.015 Over 0.109 to 0.203, incl 0.010 0.020 O
30、ver 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 1.000 0.020 0.040 SAE INTERNATIONAL AMS6470N Page 5 of 8 TABLE 4B - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, SI UNITS Nominal Wall Thickness Millimeters Total Depth of Decarburization
31、 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 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 3.3.4.5 Decarburization shall be measured by the m
32、etallographic method or by the microhardness traverse method using microhardness testing in accordance with ASTM E 384. The microhardness method shall be conducted on a hardened but untempered specimen protected during heat treatment to prevent changes in surface carbon content. Depth of decarburiza
33、tion, when measured by a microhardness method, is defined as the perpendicular distance from the surface to the depth under that surface where there is no further increase in hardness. Such measurements shall be far enough away from any adjacent surface to be uninfluenced by any decarburization on t
34、he adjacent surface. In case of dispute, the depth of decarburization determined using the microhardness traverse method shall govern. 3.3.4.5.1 When determining the depth of decarburization, it is permissible to disregard local areas provided the decarburization of such areas does not exceed the li
35、mits of Tables 3 and 4 by more than 0.005 inch (0.12 mm) and the width is 0.065 inch (1.65 mm) or less. 3.4 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. 3.4
36、.1 Steel shall be aircraft quality conforming to AMS2301. 3.4.2 Bars and mechanical tubing ordered hot rolled or cold drawn or ground, turned, or 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 m
37、achined, ground, turned, or polished surface. 3.4.3 Grain flow of die forgings, except in areas that contain flash-line end grain, shall follow the general contour of the forgings showing no evidence of reentrant grain flow. 3.5 Tolerances 3.5.1 Bars In accordance with AMS2251. 3.5.2 Mechanical Tubi
38、ng In accordance with AMS2253. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection The vendor 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 confirma
39、tory testing deemed necessary to ensure that the product conforms to specified requirements. SAE INTERNATIONAL AMS6470N Page 6 of 8 4.2 Classification of Tests 4.2.1 Acceptance Tests Composition (3.1), condition (3.2), macrostructure (3.3.1), average grain size (3.3.2), hardenability (3.3.3), decarb
40、urization (3.3.4), frequency-severity cleanliness rating (3.4.1), and tolerances (3.5) are acceptance tests and shall be performed on each heat or lot as applicable. 4.2.2 Periodic Tests Grain flow of die forgings (3.4.3) is a periodic test and shall be performed at a frequency selected by the vendo
41、r unless frequency of testing is specified by purchaser. 4.3 Sampling and Testing 4.3.1 Bars, Mechanical Tubing, and Forging Stock In accordance 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 rep
42、ort showing the producer identity, country where the metal was melted (e. g., final melt in the case of metal processed by multiple melting operations), the results of tests for composition, macrostructure, hardenability, and frequency-severity cleanliness rating of each heat and for condition and a
43、verage 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, AMS6470N, product form and size (and/or part number, if applicable), and quantity. If forgings are supplied, the size a
44、nd 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 3.2.1.3). 4.4.3 The producer of forging stock shall furnish with each shipment a report showing the producer identit
45、y, 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, hardenability, and frequency-severity cleanliness rating of each heat. This report shall include the purchase order number
46、, heat number, AMS6470N, size and quantity 4.5 Resampling and Retesting 4.5.1 Bars, Mechanical Tubing, and Forging Stock In accordance with AMS2370. 4.5.2 Forgings In accordance with AMS2372. 5. PREPARATION FOR DELIVERY 5.1 Sizes Except when exact lengths or multiples of exact lengths are ordered, s
47、traight 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). SAE INTERNATIONAL AMS6470N Page 7 of 8 5.2 Identification 5.2.1 Bars and Mechanical Tubing In accordance with AMS28
48、06. 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 from corrosion prior to shipment. 5.4 Packaging The product shall be pre
49、pared 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 quotations and when acknowledging purchase orders. 7. REJECTIONS Product not conforming to
