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 there
2、from, 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 2011 SAE International All rights reserved. No part of this publication m
3、ay 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 (outside U
4、SA) 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/AMS6278DAEROSPACEMATERIALSPECIFICATIONAMS6278 REV. D Issued 1985-10 Revised 2011-06Supersedin
5、g AMS6278C Steel, Bars, Forgings, and Tubing 4.1Cr - 3.4Ni - 4.2Mo - 1.2V (0.11 - 0.15C) Premium Aircraft-Quality for Bearing Applications Double Vacuum Melted (Composition similar to UNS K91231) RATIONALE AMS6278D results from a Five-Year Review and update of this specification. 1. SCOPE 1.1 Form T
6、his specification covers a premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock. 1.2 Application These products have been used typically for critical carburized parts, such as bearings, operating under heavy loads and high speeds at moderate t
7、emperatures, and subject to very rigid inspection standards, 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 may wor
8、k 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 International, 400 Co
9、mmonwealth 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 Steels AMS
10、2300 Steel Cleanliness, Premium Aircraft-Quality Magnetic Particle Inspection Procedure Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AMS6278D Page 2 of 8 AMS2370 Quality Assurance Sampling and
11、 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-Resistant Steels and Alloy
12、s 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 19428-2959, Tel: 610-832-958
13、5, www.astm.org.ASTM A 370 Mechanical Testing of Steel Products ASTM A 604 Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets ASTM E 45 Determining the Inclusion Content of Steel ASTM E 112 Determining Average Grain Size ASTM E 350 Chemical Analysis of Carbon Steel, Low-Alloy
14、Steel, Silicon Electrical Steel, Ingot Iron, and Wrought Iron ASTM E 384 Microindentation 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 spectrochemical
15、methods, or by other analytical methods acceptable to purchaser. TABLE 1 - Composition Element min max Carbon 0.11 0.15 Manganese 0.15 0.35Silicon 0.10 0.25 Phosphorus - 0.015Sulfur - 0.010Chromium 4.00 4.25 Nickel 3.20 3.60Molybdenum 4.00 4.50Vanadium 1.13 1.33 Cobalt - 0.25Tungsten - 0.15Copper -
16、0.10Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AMS6278D Page 3 of 8 3.1.1 Check Analysis Composition variations shall meet the applicable requirements of AMS2259. 3.2 Melting Practice Steel
17、shall be double vacuum melted, using vacuum induction melting followed by vacuum 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 A 370: 3.3.1 Bars Bar shall not be cut fro
18、m plate. 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 hardness not higher than 27 HRC, or equivalent (See 8.2). 3.3.1.2 Bars Over 0.500 Inch (12.70 mm) in Nominal
19、Diameter or Least Distance Between Parallel Sides Hot finished and annealed, unless otherwise ordered, having hardness not higher than 255 HB, or equivalent (See 8.2). Bars ordered cold finished may have hardness as high as 269 HB, or equivalent (See 8.2). 3.3.2 Forgings As ordered. 3.3.3 Mechanical
20、 Tubing Cold finished, unless otherwise ordered, having hardness not higher than 272 HB, or equivalent (See 8.2). Tubing ordered hot finished and annealed shall have hardness not higher than 248 HB, or equivalent (See 8.2). 3.3.4 Forging Stock As ordered by the forging manufacturer. 3.4 Properties T
21、he product shall conform to the following requirements; hardness testing shall be performed in accordance with ASTM A 370: 3.4.1 Macrostructure Visual examination of transverse full cross-sections from bars, billets, tube rounds or forging stock, etched in hot hydrochloric acid in accordance with AS
22、TM 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 in Table 2. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without li
23、cense from IHS-,-,-SAE AMS6278D Page 4 of 8 TABLE 2 - Macrostructure Limits Class Condition Severity 1 Freckles A 2 White Spots A 3 Radial Segregation B 4 Ring Pattern B 3.4.1.1 If tubes are produced directly from ingots or large blooms, transverse sections may be taken from tubes rather than tube r
24、ounds. Macrostructure standards for such tubes shall be as agreed upon by purchaser and vendor. 3.4.2 Micro-Inclusion Rating of Each Heat No specimen shall exceed the limits shown in Table 3, determined in accordance with ASTM E 45, Method D. TABLE 3 - Micro-Inclusion Rating Limits AThin AHeavy BThi
25、n BHeavy CThin CHeavy DThin DHeavy Worst Field Severity 1.5 1.0 1.0 1.0 1.0 1.0 1.5 1.0 Worst Field Frequency, maximum (a) 1 (a) 1 (a) 1 3 1 Total Rateable Fields, Frequency, maximum (b) 1 (b) 1 (b) 1 8 1 (a) - Combined A+B+C; not more than 3 fields. (b) - Combined A+B+C; not more than 8 fields. 3.4
26、.2.1 A rateable field is defined as one that has a type A, B, C, or D inclusion rating of at least No. 1.0 thin or heavy in accordance with the Jernkontoret chart, Plate -r, ASTM E 45. 3.4.3 Average Grain Size of Bars, Forgings and Tubing Shall be ASTM No. 5 or finer, determined in accordance with A
27、STM E 112. 3.4.4 Response to Heat Treatment of Bars, Forgings and Tubing Specimens (See 4.3.3) protected by suitable means or treated in a neutral atmosphere or neutral salt to minimize scaling and prevent either carburization or decarburization, shall have average hardness not lower than 35 HRC aft
28、er being heated to 2000 to 2025 F (1093 to 1107 C) by any convenient means, held to equalize at temperature, and either quenched into salt bath at 1100 to 1150 F (593 to 621 C), held in salt bath for 2 minutes 0.2, and air cooled to room temperature or directly cooled to room temperature at a rate e
29、quivalent to air cooling, and tempered for 2 hours 0.25 at 975 to 1025 F (521 to 552 C). 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 polished surfaces. Decarburization on tubing ID shall not exceed the
30、 maximum depth specified in Table 5. 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 vendor. 3.4.5.3 Decarburization of bars to which 3.4.5.1 or 3.4.5.2 is not a
31、pplicable shall be not greater than shown in Table 4. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AMS6278D Page 5 of 8 TABLE 4A - Maximum Decarburization, Inch/Pound Units Nominal Diameter or
32、 Distance Between Parallel Sides Inches Total Depth of DecarburizationInch Up to 0.500, incl 0.015 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 4B - Maximum Decarburization, SI Un
33、its Nominal Diameter or Distance Between Parallel Sides MillimetersTotal Depth of DecarburizationMillimetersUp 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 76.20, incl 1.27 Over 76.20 to 101.60, incl 1.65 Over 101.60 to 127.00, incl 2.41 3.4.5.4 Dec
34、arburization of tubing to which 3.4.5.1 or 3.4.5.2 is not applicable shall be not greater than shown in Table 5. TABLE 5A - Maximum Decarburization, Inch/Pound Units Nominal Outside Diameter Inches Total Depth of DecarburizationInch Up to 1.000, incl 0.025 Over 1.000 to 2.000, incl 0.035 Over 2.000
35、to 3.000, incl 0.045 Over 3.000 to 4.000, incl 0.055 Over 4.000 to 5.000, incl 0.080 TABLE 5B - Maximum Decarburization, SI Units Nominal Outside Diameter MillimetersTotal Depth of DecarburizationMillimetersUp to 25.40, incl 0.64 Over 25.40 to 50.80, incl 0.89 Over 50.80 to 76.20, incl 1.14 Over 76.
36、20 to 101.60, incl 1.40 Over 101.60 to 127.00, incl 2.03 3.4.5.5 Decarburization 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
37、 a hardened but untempered specimen protected during heat treatment to prevent changes 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 in
38、crease 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. Copyright SAE International Pr
39、ovided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AMS6278D Page 6 of 8 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 exce
40、ed the above limits by more than 0.005 inch (0.13 mm) and the width is 0.065 inch (1.65 mm) or less. 3.5 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
41、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, or polished, shall, after removal of the standard stock removal allowance in accordance with AS1182, be free from seams, laps, tears, and cracks open t
42、o the ground, turned, or polished surface. 3.5.3 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. 3.6 Tolerances 3.6.1 Bars In accordance with AMS2251. 3.6.2 Mechanical Tubing
43、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 perform any confirmatory t
44、esting deemed necessary to ensure that the product conforms to specified requirements. 4.2 Classification of Tests 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), decarb
45、urization (3.4.5), and tolerances (3.6) are acceptance tests and shall be performed on each heat or lot as applicable. 4.2.2 Periodic Tests Frequency-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 ve
46、ndor 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. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license fr
47、om IHS-,-,-SAE AMS6278D Page 7 of 8 4.3.2 Forgings In accordance with AMS2372. 4.3.3 Samples for response to heat treatment (See 3.4.4) shall be as follows: 4.3.3.1 Specimens from bars shall be full cross-sections of the bar, ground or machined on both faces normal to the axis so that length is 0.50
48、0 inch 0.010 (12.70 mm 0.25). 4.3.3.2 Specimens from mechanical tubing shall be full cross-sections of the tubing, shall have wall thickness not over 0.625 inch (15.88 mm) with wall thicknesses over 0.625 inch (15.88 mm) being turned to 0.625 inch 0.010 (15.88 mm 0.25), and shall be ground or machined on both faces so that length is 0.500 inch 0.010 (12.70 mm 0.25). 4.4 Reports 4.4.1 The vendor of bars, forgings or tubing shall furnish with each shipment a report showing the results of tests for composition, macrostructure and mi
