1、_ 6$(7HFKQLFDO6WDQGDUGV%RDUG5XOHVSURYLGHWKDW7KLVUHSRUWLVSXEOLVKH GE6$(WRDGYDQFHWKHVWDWHRIWHFKQLFDODQGHQJL neering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole res
2、ponsibility RIWKHXVHU 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 2016 SAE International All rights reserved. No part of this publication may be reprodu
3、ced, 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: 724-
4、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/AMS6278E AEROSPACE MATERIAL SPECIFICATION AMS6278 REV. E Issued 1985-10 Revised 2016-02 Superseding AMS627
5、8D 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 AMS6278E results from a Five-Year Review and update of this specification that revises microcleanlines
6、s and decarburization testing, sampling for response to heat treatment and reporting. 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. 1.2 Application These products have been used typically f
7、or critical carburized parts, such as bearings, operating under heavy loads and high speeds at moderate temperatures, 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 t
8、he 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 document issue is specified. When the referenced document has been cancelled and no superseding document has been specified, the last pu
9、blished 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 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org. AMS2251 Tolerances, Low-Alloy Steel Bars AMS2253 Tolerances,
10、Carbon and Alloy Steel Tubing AMS2259 Chemical Check Analysis Limits, Wrought Low-Alloy and Carbon Steels SAE INTERNATIONAL $06 E Page 2 of 9 AMS2300 Steel Cleanliness, Premium Aircraft-Quality Magnetic Particle Inspection Procedure AMS2370 Quality Assurance Sampling and Testing, Carbon and Low-Allo
11、y 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 Alloys AMS2808 Identification Forgin
12、gs 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: 610-832-9585, www.astm.org. ASTM A370 Mechan
13、ical Testing of Steel Products ASTM A604 Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets ASTM E45 Determining the Inclusion Content of Steel ASTM E112 Determining Average Grain Size ASTM E350 Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingo
14、t Iron, and Wrought Iron ASTM E384 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 E350, by spectrochemical methods, or by other analytical method
15、s acceptable to purchaser. Table 1 - Composition Element min max Carbon 0.11 0.15 Manganese 0.15 0.35 Silicon 0.10 0.25 Phosphorus - 0.015 Sulfur - 0.010 Chromium 4.00 4.25 Nickel 3.20 3.60 Molybdenum 4.00 4.50 Vanadium 1.13 1.33 Cobalt - 0.25 Tungsten - 0.15 Copper - 0.10 SAE INTERNATIONAL $06 E Pa
16、ge 3 of 9 3.1.1 Check Analysis Composition variations shall meet the applicable requirements of AMS2259. 3.2 Melting Practice Steel shall be double vacuum melted, using vacuum induction melting followed by vacuum consumable electrode remelting (VAR). 3.3 Condition The product shall be supplied in th
17、e following condition; hardness and tensile strength shall be determined in accordance with ASTM A370: 3.3.1 Bars Bar shall not be cut from plate (also see 4.4.2). 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
18、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 Diameter or Least Distance Between Parallel Sides Hot finished and annealed, unless otherwise ordered, having hardness not higher than 255 HB, or
19、 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 Tubing Cold finished, unless otherwise ordered, having hardness not higher than 272 HB, or equivalent (see 8.2). Tubing ordered hot finished and
20、 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 The product shall conform to the following requirements; hardness testing shall be performed in accordance with ASTM A370: SAE INTERNATIONAL $06 E
21、 Page 4 of 9 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 ASTM A604, shall show no pipe or cracks. Porosity, segregation, inclusions, and other imperfections shall be no
22、worse than the macrographs of ASTM A604 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 3.4.1.1 If tubes are produced directly from ingots or large blooms, transverse sections may be taken from tubes rath
23、er than tube rounds. Macrostructure standards for such tubes shall be as agreed upon by purchaser and producer. 3.4.2 Micro-Inclusion Rating of Each Heat No specimen shall exceed the limits shown in Table 3, determined in accordance with ASTM E45, Method D. Table 3 - Micro-inclusion rating limits A
24、Thin A Heavy B Thin B Heavy C Thin C Heavy D Thin D Heavy 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
25、more than 8 fields. 3.4.2.1 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 ASTM E45. 3.4.3 Average Grain Size of Bars, Forgings and Tubing Shall be ASTM No. 5 or finer, determined in accordance with ASTM E112. 3.
26、4.4 Response to Heat Treatment of Bars, Forgings, Tubing and Forging Stock 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 a
27、fter 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 minutes, and air cooled to room temperature or directly cooled to room temperature a
28、t a rate equivalent to air cooling, and tempered for 2 hours 0.25 hours 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 shal
29、l not exceed the 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 producer. SAE INTERNATIONAL $06 E Page 5 of 9 3.4.5.3 Decarb
30、urization of bars that 3.4.5.1 or 3.4.5.2 is not applicable shall be not greater than shown in Table 4. Table 4A - Maximum total depth of decarburization, inch/pound units Nominal Diameter or Distance Between Parallel Sides Inches Total Depth of Decarburization Inch Up to 0.500, incl 0.015 Over 0.50
31、0 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 total depth of decarburization, SI units Nominal Diameter or Distance Between Parallel Sides Millimeters Total Depth of Decarburiz
32、ation Millimeters Up 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 Decarburization of tubing that 3.4.5.1 or 3.4.5.2 is not applicable shall be not greater than
33、 shown in Table 5. Table 5A - Maximum total depth of decarburization, inch/pound units Nominal Outside Diameter Inches Total Depth of Decarburization Inch Up to 1.000, incl 0.025 Over 1.000 to 2.000, incl 0.035 Over 2.000 to 3.000, incl 0.045 Over 3.000 to 4.000, incl 0.055 Over 4.000 to 5.000, incl
34、 0.080 Table 5B - Maximum total depth of decarburization, SI units Nominal Outside Diameter Millimeters Total Depth of Decarburization Millimeters Up 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 76.20 to 101.60, incl 1.40 Over 101.60 to 127.00, incl 2.03 3.4
35、.5.5 Decarburization shall be evaluated by one of the two methods of 3.4.5.5.1 or 3.4.5.5.2. 3.4.5.5.1 Metallographic Method A cross section taken perpendicular to the surface shall be prepared, etched, and visually examined metallographically at a magnification not to exceed 100X. The product shall
36、 not show a layer of complete (ferrite) or partial decarburization exceeding the limits of Tables 4 and 5. SAE INTERNATIONAL $06 E Page 6 of 9 3.4.5.5.2 Hardness Traverse Method The total depth of decarburization shall be determined by a traverse method using microhardness testing in accordance with
37、 ASTM E384, at a magnification not exceeding 100X, conducted on a hardened but untempered specimen protected during heat treatment to prevent changes in surface carbon content. Depth of decarburization is defined as the perpendicular distance from the surface to the depth under that surface where th
38、ere is not 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. Acceptance shall be as listed in Tables 4 and 5. 3.4.5.5.3 When determining the depth of decarburization, it is permissible
39、 to disregard local areas provided the decarburization of such areas does not exceed the above limits by more than 0.005 inch (0.13 mm) and the width is 0.065 inch (1.65 mm) or less. 3.4.5.5.4 In case of dispute, the total depth of decarburization determined using the microhardness traverse method s
40、hall govern. 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 Steel shall be premium aircraft-quality conforming to AMS2300. 3.5.2 Bars and mechanical
41、 tubing ordered hot rolled or cold drawn, or machined, 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
42、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 Tolerances 3.6.1 Bars In accordance with AMS2251. 3.6.2 Mechanical Tubing In accordance with AMS2253. 4. QUALITY ASSURANCE PROVISIONS 4.1 Resp
43、onsibility for Inspection The producer of the product shall supply all samples for producerVWHVWVDQGVKDOOEHUHVSRQVLEOHIRUWKHSHUIRUPDQFHRIall required tests. Purchaser reserves the right to sample and perform any confirmatory testing deemed necessary to ensure that the product conforms to specified r
44、equirements. 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), decarburization (3.4.5), and tolerances (3.6) are acceptance tests and shall be
45、performed on each heat or lot as applicable. SAE INTERNATIONAL $06 E Page 7 of 9 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 producer unless frequency of testing is
46、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. 4.3.3 Samples for response to heat treatment (see 3.4.4) shall be as follows: Specimens for response to heat treatment shall be tak
47、en from semi-finished product representing the top and bottom of each remelted ingot or from finished product (see 4.3.3.2 for sampling of finished tubing). 4.3.3.1 Specimens shall be approximately inch (12.7 mm) thick taken midway between surface and center of the samples, and the surface to be tes
48、ted shall be ground sufficiently to remove any surface condition, scale, carburization, or decarburization that might affect readings. 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 inch (15.88 mm 0.25 mm), and shall be ground
