SAE AMS 6421G-2016 Steel Bars Forgings and Tubing 0 80Cr - 0 85Ni - 0 20Mo - 0 003B (0 35 - 0 40C) (Modified 98B37).pdf

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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2016 SAE International All rights reserved. No part of this p

3、ublication 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: +1 724-776-497

4、0 (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:/www.sae.org/technical/standards/AMS6421G AEROSPACE MATERIAL SPECIFICATION AMS6421 REV. G Issued 1951-11 Revised 2

5、016-04Superseding AMS6421F Steel, Bars, Forgings, and Tubing 0.80Cr - 0.85Ni - 0.20Mo - 0.003B (0.35 - 0.40C) (Modified 98B37) (Composition similar to UNS K13777)RATIONALE AMS6421G is a Five Year Review and update of this specification that revises macrostructure limits, decarburization testing, and

6、 reporting and adds a UNS Number. 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 typically for parts, 0.875 inch (22.22 mm) and under in section thickn

7、ess at time of heat treatment, requiring a through-hardening steel capable of developing hardness as high as 50 HRC when properly hardened and tempered, and also for parts of greater thickness requiring proportionately lower hardness, but usage is not limited to such applications. 2. APPLICABLE DOCU

8、MENTS 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. When the referenced document has been

9、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 +1 724-776-4970 (outside USA), www.s

10、ae.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 AMS6421G Page 2 of 8 AMS2301 Steel Cleanliness, Aircraft Quality Magnetic Particle Inspection Procedure AMS

11、2370 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 and Alloy Steels and Corrosion an

12、d Heat-Resistant Steels and Alloys 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,

13、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 E350 Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wrought Iron AS

14、TM E381 Macroetch Testing Steel Bars, Billets, Blooms, and Forgings 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 spectrochem

15、ical methods, or by other analytical methods acceptable to purchaser. Table 1 - Composition Element min max Carbon 0.35 0.40 Manganese 0.65 0.85 Silicon 0.15 0.35 Phosphorus - 0.025 Sulfur - 0.025 Chromium 0.70 0.90 Nickel 0.70 1.00 Molybdenum 0.15 0.25 Boron 0.0005 0.005 Copper - 0.35 SAE INTERNATI

16、ONAL AMS6421G Page 3 of 8 3.1.1 Check Analysis Composition variations shall meet the applicable requirements of AMS2259. 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

17、 cut from plate (also see 4.4.2). 3.2.1.1 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 130 ksi (896 MPa) or equivalent hardness (see 8.2). 3.2.1.2 Bars Over 0.500 Inch (12.70 mm) in Nominal Di

18、ameter or Least Distance Between Parallel Sides Hot finished and annealed, unless otherwise ordered, having hardness not higher than 229 HB, or equivalent (see 8.3). Bars ordered cold finished may have hardness as high as 248 HB, or equivalent (see 8.3). 3.2.2 Forgings As ordered. 3.2.3 Mechanical T

19、ubing Cold finished unless otherwise ordered having hardness not higher 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 Stock As ordered by the forging manufacturer. 3.3 Properties The p

20、roduct shall conform to the following requirements; hardness testing shall be performed in accordance with ASTM A370: 3.3.1 Macrostructure Visual examination of transverse full cross-sections from bars, billets, tube rounds, and forging stock, etched in hot hydrochloric acid in accordance with ASTM

21、E381, 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 Square Inches Square Centimeters Macrographs Up to 36, incl Up to 232, incl S2 - R1 - C2 Over 36 to 133

22、, 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 agreement from the cognizant engineering organization. SAE INTERNATIONAL AMS6421G Page 4 of 8 3.3.2 Avera

23、ge Grain Size of Bars, Forgings, and Tubing Shall be ASTM No. 5 or finer, determined in accordance with ASTM E112. 3.3.3 Hardenability of Each Heat Shall be J1/16 inch (1.6 mm) = 59 HRC maximum and J10/16 inch (15.9 mm) = 50 HRC minimum, determined on the standard end-quench test specimen in accorda

24、nce with ASTM A255 except that the steel shall be normalized at 1700 F 10 F (927 C 6 C) and the test specimen austenitized at 1550 F 10 F (843 C 6 C). 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 polish

25、ed surfaces. Decarburization on the tubing ID shall not exceed the maximum depth specified in Table 4. 3.3.4.2 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.

26、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. Table 3A - Maximum decarburization limits, inch/pound units Nominal Diameter or Distance Between Parallel Sides Inches Total Depth of Decarburization Inch Up to 0.375, incl 0.010 Ove

27、r 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 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 decarburization limits, SI u

28、nits Nominal Diameter or Distance Between Parallel Sides Millimeters Total Depth of Decarburization Millimeters Up to 9.52, incl 0.25 Over 9.52 to 12.70, incl 0.30 Over 12.70 to 15.88, incl 0.36 Over 15.88 to 25.40, incl 0.43 Over 25.40 to 38.10, incl 0.51 Over 38.10 to 50.80, incl 0.64 Over 50.80 t

29、o 63.50, incl 0.76 Over 63.50 to 76.20, incl 0.89 Over 76.20 to 101.60, incl 1.14 SAE INTERNATIONAL AMS6421G Page 5 of 8 3.3.4.4 Decarburization 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 4A - Maximum decarburization limits, inch/pound units

30、 Nominal Wall Thickness Inches Total Depth of Decarburization Inch ID Total Depth of Decarburization Inch OD Up to 0.109, incl 0.008 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 1.00

31、0 0.020 0.040 Table 4B - Maximum decarburization limits, SI units Nominal Wall Thickness Millimeter Total Depth of Decarburization Millimeters ID Total Depth of Decarburization Millimeters OD Up to 2.77, incl 0.20 0.38 Over 2.77 to 5.16, incl 0.25 0.51 Over 5.16 to 10.16, incl 0.30 0.64 Over 10.16 t

32、o 15.24, incl 0.38 0.76 Over 15.24 to 25.40, incl 0.43 0.89 Over 25.40 0.51 1.02 3.3.4.5 Decarburization shall be evaluated by one of the two methods of 3.3.4.5.1 or 3.3.4.5.2. 3.3.4.5.1 Metallographic Method A cross section taken perpendicular to the surface shall be prepared, etched, and visually

33、examined metallographically at a magnification not to exceed 100X. Optical indications of decarburization shall not show a layer of complete (ferrite) or partial decarburization exceeding the limits of Tables 3 or 4. 3.3.4.5.2 Hardness Traverse Method The total depth of decarburization shall be dete

34、rmined by a traverse method using microindentation hardness testing in accordance 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 a

35、s the perpendicular distance from the surface to the depth under that surface 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 Tabl

36、es 3 or 4. 3.3.4.6 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 (0.13 mm) and the width is 0.065 inch (1.65 mm) or less. 3.3.4.7 In case of dispute, the to

37、tal depth of decarburization determined using the microindentation hardness traverse method shall govern. SAE INTERNATIONAL AMS6421G Page 6 of 8 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

38、 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, or ground, turned or polished, shall, after removal of the standard stock removal allowance in accordance with AS1182, be free from se

39、ams, laps, tears, and cracks open to the machined, ground, turned, or polished surface. 3.4.3 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. 3.5 Tolerances 3.5.1 Bars In acco

40、rdance with AMS2251. 3.5.2 Mechanical Tubing In accordance with AMS2253. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection 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 t

41、he right to sample and perform any confirmatory testing 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 (3.2), macrostructure (3.3.1), average grain size (3.3.2), hardenability (3.3.3), de

42、carburization (3.3.4), frequency-severity cleanliness (3.4.1), and tolerances (3.5) are acceptance tests and shall be performed on each heat or lot as applicable. 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 producer

43、 unless a 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. 4.3.2 Forgings In accordance with AMS2372. SAE INTERNATIONAL AMS6421G Page 7 of 8 4.4 Reports 4.4.1 The producer of the bar, forgings and tu

44、bing shall furnish with each shipment a report showing the producer identity, country where the metal was melted (e.g., final melt in the case of metal processed by multiple melting operations), results of composition, macrostructure, hardenability, and frequency-severity cleanliness rating for each

45、 heat, and for condition and average grain size 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, AMS6421G, product form and size (and/or part number, if applicable) and quantity. If forg

46、ings 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 3.2.1). 4.4.3 The producer of forging stock shall furnish with each shipment a report showin

47、g the producer identity, country where the metal was melted (e.g., final melt in the case of metal processed by multiple melting operations), results of tests for composition, macrostructure, hardenability, and frequency-severity cleanliness rating of each heat and the results of any additional prop

48、erty requirements imposed by 8.6. This report shall include the purchase order number, heat number, AMS6421G, size and quantity. 4.5 Resampling and Retesting Shall be as follows: 4.5.1 Bars, Mechanical Tubing and Forging Stock In accordance with AMS2370. 4.5.2 Forgings In accordance with AMS2372. 5.

49、 PREPARATION FOR DELIVERY 5.1 Sizes Except when exact lengths or multiples of exact lengths are ordered, straight bars and tubing will be acceptable in mill 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 Identification Shall be as follows: 5.2.1 Bars and Mechanical Tubing In accordance with AMS2806. 5.2.2 Forging