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 reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.Copyright 2013 SAE InternationalAll rights reserved. No part of this publication may b
3、e 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 (outside USA)Fax
4、: 724-776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedbackon this Technical Report, please visithttp:/www.sae.org/technical/standards/AMS6475KAEROSPACEMATERIALSPECIFICATIONAMS6475 REV. KIssued 1945-07Revised 2013-06Superseding AMS6475JStee
5、l, Nitriding, Bars, Forgings, and Tubing1.1Cr 3.5Ni 0.25Mo 1.2Al (0.21 0.26C)(Composition similar to UNS K52355)RATIONALEAMS6475K is a five year review and update of this specification.1. SCOPE1.1 FormThis specification covers an age hardenable nitriding grade of aircraft-quality, low-alloy steel in
6、 the form of bars, forgings, mechanical tubing, and forging stock.1.2 ApplicationThese products have been used typically for nitrided parts requiring highest surface hardness, high core hardness, resistance to heat, and less distortion than parts made from steel requiring quenching to case harden, b
7、ut usage is not limited to such applications.2. APPLICABLE DOCUMENTSThe issue of the following documents in effect on the date of the purchase order forms a part of this document to the extent specified herein. The supplier may work to a subsequent revision of a document unless a specific document i
8、ssue 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 PublicationsAvailable from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside
9、USA and Canada) or 724-776-4970 (outside USA), www.sae.org.AMS2251 Tolerances, Low-Alloy Steel BarsAMS2253 Tolerances, Carbon and Alloy Steel TubingAMS2259 Chemical Check Analysis Limits, Wrought Low-Alloy and Carbon SteelsAMS2301 Steel Cleanliness, Aircraft-Quality, Magnetic Particle Inspection Pro
10、cedureSAE AMS6475K Page 2 of 8AMS2370 Quality Assurance Sampling and Testing, Carbon and Low-Alloy Steel Wrought Products and Forging StockAMS2372 Quality Assurance Sampling and Testing, Carbon and Low-Alloy Steel ForgingsAMS2806 Identification, Bars, Wire, Mechanical Tubing, and Extrusions, Carbon
11、and Alloy Steels and Corrosion and Heat-Resistant Steels and AlloysAMS2808 Identification, ForgingsAS1182 Standard Stock Removal Allowance, Aircraft-Quality and Premium-Aircraft Quality Steel Bars and Mechanical Tubing2.2 ASTM PublicationsAvailable from ASTM International, 100 Barr Harbor Drive, P.O
12、. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org.ASTM A 370 Mechanical Testing of Steel ProductsASTM E 112 Determining Average Grain SizeASTM E 350 Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wrought IronASTM E 381 Method
13、 of Macroetch Testing Steel Bars, Billets, Blooms, and ForgingsASTM E 384 Knoop and Vickers Hardness of Materials3. TECHNICAL REQUIREMENTS3.1 CompositionShall conform to the percentages by weight shown in Table 1, determined by wet chemical methods in accordance with ASTM E 350, by spectrochemical m
14、ethods, or by other analytical methods acceptable to purchaser.TABLE 1 - COMPOSITIONElement min maxCarbon 0.21 0.26Manganese 0.50 0.70Silicon 0.20 0.40Phosphorus - 0.025Sulfur - 0.025Chromium 1.00 1.25Nickel 3.25 3.75Molybdenum 0.20 0.30Aluminum 1.10 1.40Copper - 0.353.1.1 Check AnalysisComposition
15、variations shall meet the applicable requirements of AMS2259.3.2 ConditionThe product shall be supplied in the following condition; hardness and tensile strength shall be determined in accordance with ASTM A 370:SAE AMS6475K Page 3 of 83.2.1 Bars3.2.1.1 Bars 0.500 Inch (12.70 mm) and Under in Nomina
16、l Diameter or Least Distance Between Parallel SidesCold finished having tensile strength not higher than 125 ksi (862 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 SidesHot finished, unless otherwise ordered, havi
17、ng hardness not higher than 241 HB, or equivalent (See 8.3). Bars ordered cold finished may have hardness as high as 255 HB, or equivalent (See 8.3).3.2.1.3 Bars shall not be cut from plate.3.2.2 ForgingsAs ordered.3.2.3 Mechanical TubingCold finished, unless otherwise ordered, having hardness not h
18、igher 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 StockAs ordered by the forging manufacturer.3.3 PropertiesThe product shall conform to the following requirements; hardness and tensi
19、le testing shall be performed in accordance with ASTM A 370:3.3.1 MacrostructureVisual examination of transverse full cross-sections from bars, billets, tube rounds (not hollows) or forging stock, etched in hot hydrochloric acid in accordance with ASTM E 381, shall show no pipe or cracks. Porosity,
20、segregation, inclusions, and other imperfections shall be no worse than the macrographs of ASTM E 381 shown in Table 2.TABLE 2 - MACROSTRUCTURESection SizeSquare InchesSection SizeSquare CentimetersMacrographsUp to 36, incl Up to 232, incl S2 - R1 - C2Over 36 to 133, incl Over 232 to 858, incl S2 -
21、R2 - C3Over 133 Over 858 Note 1Note 1 Limits for larger sizes shall be agreed upon by purchaser and vendor. The purchaser shall have written approval from the cognizant engineering organization.3.3.1.1 If tubes are produced directly from ingots or large blooms, transverse sections may be taken from
22、the tubes rather than tube rounds. Macroetch standards for such tubes shall be as agreed upon by purchaser and vendor3.3.2 Average Grain Size of Bars, Forgings and TubingShall be ASTM No. 5 or finer determined in accordance with ASTM E 112.SAE AMS6475K Page 4 of 83.3.3 Decarburization3.3.3.1 Bars an
23、d tubing ordered ground, turned, or polished shall be free from decarburization on the ground, turned, or polished surfaces. Decarburization on tubing ID shall not exceed the maximum depth specified in 3.3.3.4.3.3.3.2 Allowable decarburization of bars, billets, and tube rounds or tubing ordered for
24、redrawing or forging or to specified microstructural requirements shall be as agreed upon by purchaser and vendor.3.3.3.3 Decarburization of bars to which 3.3.3.1 or 3.3.3.2 is not applicable shall be not greater than shown in Table 3.TABLE 3A - MAXIMUM DEPTH OF DECARBURIZATION, BARS, INCH/POUND UNI
25、TSNominal Diameter or DistanceBetween Parallel SidesInchesTotal Depthof DecarburizationInchUp to 0.500, incl 0.030Over 0.500 to 1.000, incl 0.035Over 1.000 to 1.500, incl 0.040Over 1.500 to 2.000, incl 0.050Over 2.000 to 2.500, incl 0.060Over 2.500 to 3.000, incl 0.070TABLE 3B MAXIMUM DEPTH OF DECAR
26、BURIZATION, BARS, SI UNITSNominal Diameter or DistanceBetween Parallel SidesMillimetersTotal Depthof DecarburizationMillimetersUp to 12.70, incl 0.76Over 12.70 to 25.40, incl 0.89Over 25.40 to 38.10, incl 1.02Over 38.10 to 50.80, incl 1.27Over 50.80 to 63.50, incl 1.52Over 63.50 to 76.20, incl 1.783
27、.3.3.4 Decarburization of tubing to which 3.3.3.1 or 3.3.3.2 is not applicable shall be not greater than shown in Table 4.TABLE 4A - MAXIMUM DEPTH OF DECARBURIZATION, TUBING, INCH/POUND UNITSNominal Wall ThicknessInchesTotal Depth of DecarburizationInchIDTotal Depth of DecarburizationInchODUp to 0.1
28、09, incl 0.008 0.015Over 0.109 to 0.203, incl 0.010 0.020Over 0.203 to 0.400, incl 0.012 0.025Over 0.400 to 0.600, incl 0.015 0.030Over 0.600 to 1.000, incl 0.017 0.035Over 1.000 0.020 0.040SAE AMS6475K Page 5 of 8TABLE 4B - MAXIMUM DEPTH OF DECARBURIZATION, TUBING, SI UNITSNominal Wall ThicknessMil
29、limetersTotal Depth of DecarburizationMillimetersIDTotal Depth of DecarburizationMillimetersODUp to 2.77, incl 0.20 0.38Over 2.77 to 5.16, incl 0.25 0.51Over 5.16 to 10.16, incl 0.30 0.64Over 10.16 to 15.24, incl 0.38 0.76Over 15.24 to 25.40, incl 0.43 0.89Over 25.40 0.51 1.023.3.3.5 Decarburization
30、 shall be measured by the metallographic method, by the HR30N scale hardness testing method, or by a traverse method using microhardness testing in accordance with ASTM E 384. The hardness method(s) shall be conducted on a hardened but untempered specimen protected during heat treatment to prevent c
31、hanges in surface carbon content. Depth of decarburization, when measured by a hardness method, is defined as the perpendicular distance from the surface to the depth under that surface below which there is no further increase in hardness. Such measurements shall be far enough away from any adjacent
32、 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.3.3.3.5.1 When determining the depth of decarburization, it is permissible to disregard local areas provided th
33、e decarburization of such areas does not exceed the limits by more than 0.005 inch (0.13 mm) and the width is 0.065 inch (1.65 mm) or less.3.3.4 Response to Heat Treatment 3.3.4.1 Hardness After Hardening and Tempering of Each LotSpecimens having full sections, except that bars over 3 inches (76 mm)
34、 in nominal diameter or distance between parallel sides may be reduced to 3 inches (76 mm) in nominal diameter, shall have hardness not lower than 285 HB, or equivalent (See 8.3) after normalizing at 1700 to 1750 F ( to C), air cool, hardening at 1650 F ( C), oil quench, and tempering at not lower t
35、han 1100 F (593 C). For purpose of the test of 3.3.4.2, the tempering temperature shall be adjusted above 1100 F (593 C) to produce a hardness not higher than 302 HB, or equivalent (See 8.3).3.3.4.2 After Simulated Nitriding of Each HeatTensile specimens conforming to ASTM A 370, prepared from the s
36、pecimens used for determining hardness after hardening and tempering shall meet the requirements shown in Table 5 and 3.3.4.2.1 after being heated to 975 F 10 (524 C 6), held at heat for 20 hours 0.5, and cooled in air. Sampling for this requirement and 3.3.4.2.1 shall be at least one per heat. TABL
37、E 5 - LONGITUDINAL MINIMUM TENSILE PROPERTIESRequirement ValueTensile Strength 165 ksi (1138 MPa)Yield Strength at 0.2% Offset 120 ksi ( 827 MPa)Elongation in 4D 13%Reduction of Area 40%3.3.4.2.1 HardnessShall be 352 to 401 HB, or equivalent (See 8.3).SAE AMS6475K Page 6 of 83.4 QualityThe product,
38、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.3.4.1 Steel shall be aircraft-quality conforming to AMS2301.3.4.2 Bars and mechanical tubing ordered hot rolled or cold drawn, ground
39、, 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 machined, ground, turned, or polished surface.3.4.3 Grain flow of die forgings, except in areas which contain flash-line end grain, sh
40、all follow the general contour of the forgings showing no evidence of reentrant grain flow.3.5 Tolerances3.5.1 BarsIn accordance with AMS2251.3.5.2 Mechanical TubingIn accordance with AMS2253.4. QUALITY ASSURANCE PROVISIONS4.1 Responsibility for InspectionThe vendor of the product shall supply all s
41、amples 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 product conforms to specified requirements.4.2 Classification of Tests4.2.1 Acceptance TestsComp
42、osition (3.1), condition (3.2), macrostructure (3.3.1), average grain size (3.3.2), decarburization (3.3.3), response to heat treatment (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 Per
43、iodic TestsGrain flow of die forgings (3.4.3) is a periodic test and shall be performed at a frequency selected by the vendor unless frequency of testing is specified by purchaser.4.3 Sampling and Testing4.3.1 Bars, Tubing, and Forging StockIn accordance with AMS2370.4.3.2 ForgingsIn accordance with
44、 AMS2372.SAE AMS6475K Page 7 of 84.4 Reports4.4.1 The vendor bars, forgings and tubing shall furnish with each shipment a report showing the results of tests for composition, macrostructure, frequency-severity cleanliness rating, and tensile properties and hardness after simulated nitriding of each
45、heat and for average grain size, and hardness after hardening and tempering of each lot, and stating that the product conforms to all other technical requirements. This report shall include the purchase order number, heat and lot numbers, AMS6475K, product form and size (and/or part number, if appli
46、cable), 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 If the ship size/shape is cut from a larger cross section, report the nominal metallurgically worked size (See 3.3.1).4.4.3 The vendor of forging stock shall furni
47、sh with each shipment a report showing the results of tests for composition, macrostructure, frequency-severity cleanliness rating and tensile properties and hardness after simulated nitriding of each heat. This report shall include the purchase order number, heat number, AMS6475K, size and quantity
48、.4.5 Resampling and Retesting4.5.1 Bars, Mechanical Tubing, and Forging StockIn accordance with AMS2370.4.5.2 ForgingsIn accordance with AMS2372.5. PREPARATION FOR DELIVERY5.1 SizesExcept when exact lengths or multiples of exact lengths are ordered, straight bars and tubing will be acceptable in mil
49、l 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 Identification5.2.1 Bars and Mechanical TubingIn accordance with AMS2806.5.2.2 ForgingsIn accordance with AMS2808.5.2.3 Forging StockAs agreed upon by purchaser and vendor.5.3 Protective TreatmentBars and mechanical tubing ordered cold drawn, cold rolled, ground, turned, or polish
