SAE AMS 6424G-2017 Steel Bars Forgings and Tubing 0 80Cr - 1 8Ni - 0 25Mo (0 49 - 0 55C) (UNS K22950).pdf

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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 ther

2、efrom, 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 2017 SAE International All rights reserved. No part of this

3、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) Tel: +1 724-776-49

4、70 (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:/standards.sae.org/AMS6424G AEROSPACE MATERIAL SPECIFICATION AMS6424 REV. G Issued 1973-05 Revised 2017-08 Supers

5、eding AMS6424F Steel Bars, Forgings, and Tubing 0.80Cr - 1.8Ni - 0.25Mo (0.49 - 0.55C) (Composition similar to UNS K22950) RATIONALE AMS6424G results from a Five-Year Review and update of this specification that revises grain size determination (3.1.1 and 3.3.2), decarburization determination (3.3.4

6、), surface quality (3.4.2), testing frequency (4.2), reporting (4.4) and identification (5.2). 1. SCOPE 1.1 Form This specification covers an aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock. 1.2 Application These products have been used primarily

7、 for parts 3.5 inches (90 mm) and under in nominal section-thickness at time of heat treatment requiring a through-hardening steel capable of developing hardness as high as 40 HRC and also for parts with thicker cross-section which require proportionately lower hardness, but usage is not limited to

8、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 work to a subsequent revision of a document unless a specific document issue is specified. W

9、hen 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 (inside USA and Canada) or

10、 +1 724-776-4970 (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 SAE INTERNATIONAL AMS6424G Page 2 of 9 AMS2301 Steel Cleanliness, Aircraft Quality Magnetic

11、 Particle Inspection Procedure AMS2370 Quality 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

12、and Alloy Steels and Corrosion and Heat-Resistant Steels and Alloys AMS2808 Identification, Forgings ARP1917 Clarification of Terms Used in Aerospace Metals Specifications AS1182 Standard Stock Removal Allowance, Aircraft-Quality and Premium Aircraft-Quality Steel, Bars and Mechanical Tubing 2.2 AST

13、M 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 A255 Determining Hardenability of Steel ASTM A370 Mechanical Testing of Steel Products ASTM E112 Determining Average Grain Size ASTM E140 Ha

14、rdness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness ASTM E350 Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wrought

15、Iron ASTM E381 Macroetch Testing Steel Bars, Billets, Blooms, and Forgings ASTM E384 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 E350, by spect

16、rochemical methods, or by other analytical methods acceptable to purchaser. Table 1 - Composition Element Min Max Carbon 0.49 0.55 Manganese 0.65 0.85 Silicon 0.15 0.35 Phosphorous - 0.025 Sulfur - 0.025 Chromium 0.70 0.90 Nickel 1.65 2.00 Molybdenum 0.20 0.30 Copper - 0.35 SAE INTERNATIONAL AMS6424

17、G Page 3 of 9 3.1.1 Aluminum, vanadium and columbium are optional grain refining elements and need not be determined or reported unless used to satisfy the average grain size requirements of 3.3.2.2. 3.1.2 Check Analysis Composition variations shall meet the applicable requirements of AMS2259, excep

18、t that variations for carbon shall apply to over max only. 3.2 Condition The product shall be supplied in the following condition; hardness and tensile strength shall be determined in accordance with ASTM A370: 3.2.1 Bars Bar shall not be cut from plate. (Also see 4.4.2.) 3.2.1.1 Bars 0.500 Inch (12

19、.50 mm) and Under in Nominal Diameter or Least Distance Between Parallel Sides Cold finished having tensile strength not higher than 135 ksi (930 MPa) or equivalent hardness (see 8.2). 3.2.1.2 Bars Over 0.500 Inch (12.50 mm) in Nominal Diameter or Least Distance Between Parallel Sides Hot finished a

20、nd annealed unless otherwise ordered, having hardness not higher than 255 HB, or equivalent (see 8.3). Bars ordered cold finished may have hardness as high as 277 HB, or equivalent (see 8.3). 3.2.2 Forgings As ordered. 3.2.3 Mechanical Tubing Cold finished, unless otherwise ordered, having hardness

21、not higher than 28 HRC, or equivalent (see 8.3). Tubing ordered hot finished and annealed shall have hardness not higher than 23 HRC, or equivalent (see 8.3). 3.2.4 Forging Stock As ordered by the forging manufacturer. 3.3 Properties The product shall conform to the following requirements; hardness

22、testing shall be performed in accordance with ASTM A370: SAE INTERNATIONAL AMS6424G Page 4 of 9 3.3.1 Macrostructure Visual examination of transverse full cross-sections from bars, billets, tube rounds (solid, not hollow), and forging stock, etched in hot hydrochloric acid in accordance with ASTM E3

23、81 for sufficient time to develop a well-defined macrostructure, shall show no pipe or cracks. Porosity, segregation, inclusions, and other imperfections shall be no worse than the macrographs of ASTM E381 shown in Table 2. Table 2 - Macrostructure limits Cross-Sectional Area Square Inches Cross-Sec

24、tional Area Square Centimeters Macrographs Up to 36, 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 producer. The purchaser shall have written approval of the agree

25、ment 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 the tubes rather than tube rounds. Macroetch standards for such tubes shall be agreed upon by purchaser and producer. 3.3.2 Average Grain Size o

26、f Bars, Forgings and Tubing Average grain size shall be determined by either 3.3.2.1 or 3.3.2.2 3.3.2.1 Shall be ASTM No. 5 or finer determined in accordance with ASTM E112. 3.3.2.2 The product of a heat shall be considered to have an ASTM No. 5 or finer austenitic grain size if one or more of the f

27、ollowing are determined by heat analysis (see 8.5): 3.3.2.2.1 A total aluminum content of 0.020 to 0.050%. 3.3.2.2.2 An acid soluble aluminum content of 0.015 to 0.050%. 3.3.2.2.3 A vanadium content of 0.02 to 0.08%. 3.3.2.2.4 A columbium content of 0.02 to 0.05%. 3.3.3 Hardenability of Each Heat Sh

28、all be J 2/16 inch (3.175 mm) = 62 HRC min and J 12/16 inch (19.050 mm) = 55 HRC min, determined on the standard end-quench test specimen in accordance with ASTM A 255 except that the steel shall be normalized at 1700 F 10 F (925 C 6 C) and the test specimen austenitized at 1525 F 10 F (830 C 6 C).

29、3.3.4 Decarburization 3.3.4.1 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 maximum depth specified in Table 4. 3.3.4.2 Allowable decarburization of bars, billets,

30、and tube rounds ordered for redrawing or forging or to specified microstructural requirements shall be as agreed upon by purchaser and producer. SAE INTERNATIONAL AMS6424G Page 5 of 9 3.3.4.3 Decarburization of bars that 3.3.4.1 or 3.3.4.2 is not applicable shall be not greater than shown in Table 3

31、. Table 3 Table 3A - Maximum depth of decarburization, inch/pound units Nominal Diameter or Distance Between Parallel Sides Inches Total Depth of Decarburization Inch Up to 0.375, incl 0.010 Over 0.375 to 0.500, incl 0.012 Over 0.500 to 0.625, incl 0.014 Over 0.625 to 1.000, incl 0.017 Over 1.000 to

32、 1.500, incl 0.020 Over 1.500 to 2.000, incl 0.025 Over 2.000 to 2.500, incl 0.030 Over 2.500 to 3.000, incl 0.035 Over 3.000 to 4.000, incl 0.045 Table 3B - Maximum depth of decarburization, SI units Nominal Diameter or Distance Between Parallel Sides Millimeters Total Depth of Decarburization Mill

33、imeters Up to 9.50, incl 0.25 Over 9.50 to 12.50, incl 0.30 Over 12.50 to 15.50, incl 0.36 Over 15.50 to 25.00, incl 0.43 Over 25.00 to 37.50, incl 0.51 Over 37.50 to 50.00, incl 0.64 Over 50.00 to 62.50, incl 0.76 Over 62.50 to 75.00, incl 0.89 Over 75.00 to 100.00, incl 1.14 3.3.4.4 Decarburizatio

34、n of tubing that 3.3.4.1 or 3.3.4.2 is not applicable shall be not greater than shown in Table 4. Table 4 Table 4A - Maximum 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

35、0.015 Over 0.109 to 0.203, incl 0.010 0.020 Over 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 AMS6424G Page 6 of 9 Table 4B - Maximum depth of decarburization, SI units Nominal Wall Thickness Mil

36、limeters Total Depth of Decarburization Millimeter ID Total Depth of Decarburization Millimeter OD Up to 2.75, incl 0.20 0.38 Over 2.75 to 5.00, incl 0.25 0.51 Over 5.00 to 10.00, incl 0.30 0.64 Over 10.00 to 15.00, incl 0.38 0.76 Over 15.00 to 25.00, incl 0.43 0.89 Over 25.00 0.51 1.02 3.3.4.5 Deca

37、rburization shall be evaluated by one of the two methods of 3.3.4.5.1 or 3.3.4.5.2, selected at the discretion of the producer. 3.3.4.5.1 Metallographic Method A cross section taken perpendicular to the surface shall be prepared, etched, and visually examined metallographically at a magnification no

38、t to exceed 100X. The product shall not show a layer of complete (ferrite) or partial decarburization exceeding the limits of Tables 3 and 4. 3.3.4.5.2 Hardness Traverse Method The total depth of decarburization shall be determined by a traverse method using microindentation hardness testing in acco

39、rdance with 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 sur

40、face where there 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 3 and 4. 3.3.4.5.3 When determining the depth of decarburization, it i

41、s 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 the width is 0.065 inch (1.65 mm) or less. 3.3.4.5.4 In case of dispute, the total depth of decarburization determined using the microindentation h

42、ardness traverse method shall govern. 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. 3.4.1 Steel shall be aircraft quality conforming to AMS2301. 3.4.2 Ba

43、rs and mechanical tubing shall be free from seams, laps, tears, and cracks after removal of the standard stock removal allowance in accordance with AS1182. 3.4.3 Grain flow of die forgings, except in areas which contain flash-line end grain, shall follow the general contour of the forgings, showing

44、no evidence of reentrant grain flow. SAE INTERNATIONAL AMS6424G Page 7 of 9 3.5 Tolerances 3.5.1 Bars Shall conform to the applicable requirements of AMS2251. 3.5.2 Mechanical Tubing Shall conform to the applicable requirements of AMS2253. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspe

45、ction The producer of the product shall supply all samples for producers 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 requirem

46、ents. 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), decarburization (3.3.4), frequency-severity cleanliness rating (3.4.1), and tolerances (3.5) are acceptance tests and shall be perfo

47、rmed on each heat or lot as applicable. If grain refining elements (3.3.2.2) are not present, the ASTM E112 grain size test (3.3.2.1) shall be conducted on each lot. 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 produ

48、cer unless frequency of testing is specified by purchaser. If grain refining elements (3.3.2.2) are present, the ASTM E112 grain size test (3.3.2.1) shall be conducted on a periodic basis and shall be performed at a frequency selected by the producer (not to exceed one year) unless frequency of test

49、ing 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 report showing producer identity, country where the metal was melted (e.g., final melt in the case of metal processed by multiple melt