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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2013 SAE InternationalAll rights reserved. No part of this publi
3、cation 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: +1 724-776-4970 (out
4、side USA)Fax: 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/AMS6498AAEROSPACE MATERIAL SPECIFICATIONAMS6498 REV. AIssued 2009-09Revised 2013-11Supersedin
5、g AMS6498Steel Bars, Forgings, and Tubing, Nitriding1.4Cr - 1.2Mo - 0.3V (0.29 - 0.36C)Double Vacuum MeltedPremium Aircraft-Quality for Bearing Applications(Composition similar to UNS K23280)RATIONALEAMS6498A results from a Five Year Review and update of this specification.1. SCOPE1.1 FormThis speci
6、fication covers a nitriding grade of premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock. AMS6496 and AMS6497 cover UNS K23280 with other quality levels.1.2 ApplicationThese products have been used typically for nitrided parts requiring high
7、minimum core hardness with a narrow range, reduced distortion and subject to stringent magnetic particle inspection standards, but 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 sp
8、ecification to the extent specified herein. The supplier 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 appl
9、y.2.1 SAE PublicationsAvailable from SAE International, 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 BarsAMS2253 Tolerances, Carbon and Alloy Steel TubingAMS2259 Chemical Ch
10、eck Analysis Limits, Wrought Low-Alloy and Carbon SteelsSAE INTERNATIONAL AMS6498A Page 2 of 8AMS2300 Steel Cleanliness, Premium Aircraft-Quality, Magnetic Particle Inspection ProcedureAMS2370 Quality Assurance Sampling and Testing, Carbon and Low-Alloy Steel Wrought Products and Forging StockAMS237
11、2 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-Resistant Steels and AlloysAMS2808 Identification, ForgingsAS1182 Standard Stock Removal Allowance, Airc
12、raft-Quality and Premium Aircraft-Quality Steel Bars and Mechanical Tubing2.2 ASTM PublicationsAvailable from ASTM International, 100 Barr Harbor Drive, P. O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org.ASTM E 45 Determining the Inclusion Content of SteelsASTM A 255 D
13、etermining Hardenability of SteelASTM A 370 Mechanical Testing of Steel ProductsASTM A 604 Macroetch Testing of Consumable Electrode Remelted Steel Bars and BilletsASTM E 112 Determining Average Grain SizeASTM E 350 Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel,Ingot I
14、ron, and Wrought IronASTM E 384 Knoop and Vickers Hardness of Materials3. TECHNICAL REQUIREMENTS3.1 CompositionShall conform to the following percentages by weight shown in Table 1, determined by wet chemical methods in accordance with ASTM E 350, by spectrochemical methods, or by other analytical m
15、ethods acceptable to purchaser.TABLE 1 COMPOSITIONElement min maxCarbon 0.29 0.36Manganese 0.70 1.20Silicon - 0.30Phosphorus - 0.015Sulfur - 0.005Chromium 1.10 1.60Nickel 0.50 1.00Molybdenum 0.90 1.40Aluminum 0.10 0.30Vanadium 0.20 0.403.1.1 Check AnalysisComposition variations shall meet the applic
16、able requirements of AMS2259.SAE INTERNATIONAL AMS6498A Page 3 of 83.2 Melting Practice Steel shall be double vacuum melted, using vacuum induction melting (VIM) followed by vacuum arc consumable electrode remelting (VAR).3.3 ConditionThe product shall be supplied in the following condition; hardnes
17、s, tensile, and impact testing shall be performed in accordance with ASTM A 370:3.3.1 Bars3.3.1.1 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 138 ksi (950 MPa) or hardness not higher than 285
18、HB or equivalent (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 285 HB or equivalent (See 8.2). Bars ordered cold finished may have hardness as high as
19、 310 HB or equivalent (See 8.2).3.3.1.3 Bars shall not be cut from plate.3.3.2 ForgingsAs ordered.3.3.3 Mechanical TubingCold finished, unless otherwise ordered, having hardness not higher than 285 HB, or equivalent (See 8.2). Tubing ordered hot finished and annealed or tempered shall have hardness
20、not higher than 285 HB or equivalent (See 8.2).3.3.4 Forging StockAs ordered by the forging manufacturer.3.4 PropertiesThe product shall conform to the following requirements; hardness, tensile, and impact testing shall be performed in accordance with ASTM A 370:3.4.1 MacrostructureVisual examinatio
21、n 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 imperfections shall be no worse than the macrographs of ASTM A 604 shown i
22、n Table 2.TABLE 2 MACROSTRUCTURE LIMITSClass Condition Severity1FrecklsA2 White Spots A3 Radial Segregation B4 Ring Pattern B3.4.2 Micro-Inclusion RatingNo specimen shall exceed the limits shown in Table 3, determined in accordance with ASTM E 45, Method D:SAE INTERNATIONAL AMS6498A Page 4 of 8TABLE
23、 3 MICRO-INCLUSIONS RATING LIMITSType AThinAHeavyBThinBHeavyCThinCHeavyDThinDHeavyWorst Field Severity 1.5 1.0 1.0 1.0 1.0 1.0 1.5 1.0Worst Field Frequency, maximum a 1 a 1 a131Total Rateable Fields, Frequency, maximumb1b1 b151a - Combined A+B+C, not more than 3 fieldsb - Combined A+B+C, not more th
24、an 8 fields3.4.2.1 A rateable field is defined as one that has type A, B, C or D inclusion rating of at least No. 1.0 thin or heavy in accordance with Jernkontoret chart, Plate ,r, ASTM E 45.3.4.3 Average Grain SizeShall be ASTM No. 6 or finer determined in accordance with ASTM E 112.3.4.4 Response
25、to Heat Treatment3.4.4.1 Bars, Forgings and Mechanical TubingSpecimens from product shall have the properties shown in Table 4 after being austenitized by heating to 1720 F 25 (938 C 14), holding at heat for a time commensurate with section thickness, heating equipment, and procedure used, oil quenc
26、hed to below 90F (32C) followed by tempering for 2 hours minimum at no lower than 1110 F (599 C).TABLE 4 LONGITUDINAL MECHANICAL PROPERTIESPROPERTY VALUETensile Strength, min 181 ksi (1250 MPa)Yield Strength 0.2%, min 155 ksi (1070 MPa)Elongation in 4D, min 12%Charpy Vnotch, min 22 ft-lb (30 J)Hardn
27、ess 375 to 450 HB, or equivalent (See 8.2)3.4.4.2 Forging StockWhen a sample of stock is forged to a test coupon and heat treated as in 3.4.4.1, specimens taken from the heat treated coupon shall conform to the requirements of 3.4.4.1. If specimens taken from the stock after heat treatment as in 3.4
28、.4.1 conform to the requirements of 3.4.4.1, tests shall be accepted as equivalent to tests of a forged coupon.3.4.5 Decarburization3.4.5.1 Bars and tubing ordered ground, turned, or polished shall be free from decarburization on the ground, turned or polished surfaces. Decarburization on tubing ID
29、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 purchaser and vendor.3.4.5.3 Decarburization of bars to which 3.4.5.1 or 3
30、.4.5.2 is not applicable shall be not greater than shown in Table 5.SAE INTERNATIONAL AMS6498A Page 5 of 8TABLE 5A - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, BARS, INCH/POUND UNITSNominal Diameter or DistanceBetween Parallel SidesInchesTotal Depthof DecarburizationInchUp to 0.500, incl 0.030Over 0.50
31、0 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 0.070Over 3.000 0.080TABLE 5B - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, BARS, SI UNITSNominal Diameter or DistanceBetween Parallel SidesMillimetersTotal Deptho
32、f 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 1.78Over 76.20 2.043.4.5.4 Decarburization of tubing to which 3.4.5.1 or 3.4.5.2 is not applicable shall
33、 be not greater than shown in Table 6.TABLE 6A - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, TUBING, INCH/POUND UNITSNominal Wall ThicknessInchesTotal Depth of DecarburizationInchIDTotal Depth of DecarburizationInchODUp to 0.109, incl 0.008 0.015Over 0.109 to 0.203, incl 0.010 0.020Over 0.203 to 0.400,
34、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 0.040TABLE 6B - MAXIMUM TOTAL DEPTH OF DECARBURIZATION, TUBING, SI UNITSNominal Wall ThicknessMillimetersTotal Depth of DecarburizationMillimeterIDTotal Depth of DecarburizationMillimetersODUp
35、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 1.02SAE INTERNATIONAL AMS6498A Page 6 of 83.4.5.5 Decarburization shall be measured by the metallographic method or by a tra
36、verse 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 decarburization, when measured by the microhardness method,
37、 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 the adjacent surface. In case of dispute, the d
38、epth of decarburization determined using the microhardness traverse methodshall govern.3.4.5.5.1 When determining the depth of decarburization, it is permissible to disregard local areas provided the decarburization of such areas does not exceed the above limits by more than 0.005 inch (0.12 mm) and
39、 the width is 0.065 inch (1.65 mm) or less.3.5 QualityThe 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-quality conforming to AMS230
40、0.3.5.2 Product ordered hot finished or cold finished 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 machined, ground, turned, or polished surface.3.5.3 Grain flow of die f
41、orgings, except in areas that contain flash-line end grain, shall follow the general contour of the forgings showing no evidence of reentrant grain flow.3.6 Tolerances3.6.1 BarsIn accordance with AMS2251.3.6.2 Mechanical TubingIn accordance with AMS2253.4. QUALITY ASSURANCE PROVISIONS4.1 Responsibil
42、ity for inspectionThe 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 confirmatory testing deemed necessary to ensure that the product conforms to specified
43、requirements.4.2 Classification of Tests4.2.1 Acceptance Tests4.2.1.1 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 (3.4.4.1), and tolerances (3.6) are acceptance tests and shall be performed on each
44、 heat or lot as applicable.4.2.1.2 When specified, decarburization (3.4.5).4.2.2 Periodic TestsFrequency-severity cleanliness rating (3.5.1), grain flow of die forgings (3.5.3) and response to heat treatment of forging stock (3.4.4.2) are periodic tests and shall be performed at a frequency selected
45、 by the vendor unless frequency of testing is specified by purchaser.SAE INTERNATIONAL AMS6498A Page 7 of 84.3 Sampling and Testing4.3.1 Bars, Mechanical Tubing, and Forging Stock In accordance with AMS2370.4.3.2 ForgingsIn accordance with AMS2372.4.4 Reports4.4.1 The producer of bars, mechanical tu
46、bing and forgings shall furnish with each shipment a report showing the producer identity and country where the metal was melted (i.e., final melt in the case of metal processed by multiple melting operations) and the results of tests for composition, macrostructure, micro-inclusion rating of each h
47、eat, and for condition, average grain size, and response to heat treatment 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, AMS6498A, melt practice, product form and size or part number,
48、 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 (See 3.3.1.3).4.4.3 The producer of forging stock shall furnish with each sh
49、ipment a report showing the producer identity and country where the metal was melted (e. g., final melt in the case of metal processed by multiple melting operations) and the composition, macrostructure and micro-inclusion rating of each heat. This report shall include the purchase order number, heat number, AMS6498A, size and quantity.4.5 Resampling and Retesting4.5.1 Bars, Mechanical Tubing, and Forging StockIn accord
