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/AMS6257F AEROSPACE MATERIAL SPECIFICATION AMS6257 REV. F Issued 1990-07 Revised 2
5、016-08Superseding AMS6257E Steel Bars, Forgings, and Tubing 1.6Si - 0.82Cr - 1.8Ni - 0.40Mo - 0.08V (0.40 - 0.44C) Consumable Electrode Vacuum Remelted Normalized and Tempered (Similar to UNS K44220) RATIONALE AMS6257F results from a review and update of this specification that revises micro-inclusi
6、on (3.4.2.1), test procedure for decarburization (3.4.4.5), quality (3.5), and reporting (4.4). 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 t
7、ypically for parts under 3.5 inches (89 mm) in thickness requiring a through-hardening steel capable of developing a minimum hardness of 52 HRC, the parts being subject to very rigid magnetic particle inspection standards, but usage is not limited to such applications. 1.2.1 Certain design and proce
8、ssing procedures may cause these products to become susceptible to stress-corrosion cracking after heat treatment; ARP1110 recommends practices to minimize such occurrences. 2. APPLICABLE DOCUMENTS The issue of the following documents in effect on the date of the purchase order forms a part of this
9、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 published issue of that document shall ap
10、ply. SAE INTERNATIONAL AMS6257F Page 2 of 10 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,
11、 Carbon and Alloy Steel Tubing AMS2259 Chemical Check Analysis Limits, Wrought Low-Alloy and Carbon Steels AMS2300 Steel Cleanliness, Premium Aircraft-Quality Magnetic Particle Inspection Procedure AMS2310 Qualification Sampling and Testing of Steels for Transverse Tensile Properties AMS2370 Quality
12、 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 AMS2750 Pyrometry AMS2806 Identification Bars, Wire, Mechanical Tubing, and Extrusions Carbon and Alloy Steels and Corrosi
13、on and Heat-Resistant Steels and Alloys AMS2808 Identification Forgings AMS-H-6875 Heat Treatment of Steel Raw Materials ARP1110 Minimizing Stress Corrosion Cracking in Wrought Forms of Steels and Corrosion Resistant Steels and Alloys ARP1917 Clarification of Terms Used in Aerospace Metals Specifica
14、tions 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 Mec
15、hanical 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 E140 Hardness Conversion Tables for Metals ASTM E350 Chemical Analysis of Carbon Ste
16、el, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wrought Iron ASTM E384 Microindentation Hardness of Materials SAE INTERNATIONAL AMS6257F Page 3 of 10 3. TECHNICAL REQUIREMENTS 3.1 Composition Shall conform to the percentages by weight shown in Table 1, determined by wet chemical metho
17、ds in accordance with ASTM E350, by spectrochemical, or by other analytical methods approved by purchaser. Table 1 - Composition Element min max Carbon 0.40 0.44 Manganese 0.65 0.90 Silicon 1.45 1.80 Phosphorus - 0.010 Sulfur - 0.008 Chromium 0.70 0.95 Nickel 1.65 2.00 Molybdenum 0.35 0.45 Vanadium
18、0.05 0.10 Copper - 0.35 3.1.1 Check Analysis Composition variations shall meet the applicable requirements of AMS2259, except that check analysis limits for carbon shall be 0.01 under minimum or over maximum. 3.2 Melting Practice Steel shall be multiple melted using vacuum consumable electrode pract
19、ice in the remelt cycle. 3.3 Condition The product shall be supplied in the following condition; hardness and tensile strength shall be determined in accordance with ASTM A370: 3.3.1 Bars and Tubing Normalized and tempered at a temperature not higher than 1250 F (677 C). Pyrometry shall be in accord
20、ance with AMS2750. 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 strength not higher than 130 ksi (896 MPa), or equivalent hardness (see 8.2). 3.3.1.2 Bars Over
21、0.500 Inch (12.70 mm) in Nominal Diameter or Least Distance Between Parallel Sides Hot finished unless otherwise ordered, having hardness not higher than 341 HB, or equivalent (see 8.3). Bars ordered cold finished may have hardness as high as 341 HB (see 8.3). 3.3.1.3 Mechanical Tubing Cold finished
22、, unless otherwise ordered, having hardness not higher than 341 HB or equivalent (see 8.3). Tubing ordered hot finished and annealed shall have hardness not higher than 99 HRB, or equivalent (see 8.3). 3.3.2 Forgings Normalized and tempered in accordance with AMS-H-6875 to a hardness not higher than
23、 341 HB, or equivalent (see 8.3). SAE INTERNATIONAL AMS6257F Page 4 of 10 3.3.3 Forging Stock As ordered by the forging manufacturer. 3.4 Properties The product shall conform to the following requirements; hardness and tensile testing shall be performed in accordance with ASTM A370: 3.4.1 Macrostruc
24、ture Visual examination of transverse sections from bars, billets, tube rounds, or forging stock, etched in hot hydrochloric acid in accordance with ASTM A604, shall not show pipe or cracks. Porosity, segregation, inclusions, and other imperfections for product 144 in2(929 cm2) and under in nominal
25、cross-sectional area shall not be 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 3.4.2 Micro-Inclusion Rating of Each Heat No specimen shall exceed the limits show
26、n in Table 3, determined in accordance with ASTM E45, Method D. Table 3 - Micro-inclusion rating limits Type A 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, Frequenc
27、y, 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 3.4.2.1 A rateable field is defined as one which has a Type A, B, C, or D inclusion rating of at least 1.0 thin or heavy in accordance with ASTM E45. 3.4.3 Average Grain Size of Bar, Forg
28、ings, and Tubing Shall be ASTM 6 or finer, determined in accordance with ASTM E112. 3.4.4 Decarburization 3.4.4.1 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 maxi
29、mum depth specified in Table 5. 3.4.4.2 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. SAE INTERNATIONAL AMS6257F Page 5 of 10 3.4.4.3 Decarburization of bars
30、 that 3.4.4.1 or 3.4.4.2 is not applicable shall be not greater than shown in Table 4. Table 4A - Maximum 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 0.50
31、0 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 5.000, incl 0.045 Table 4B - Maximum decarburization, SI units Nominal Diameter or Distance Between Par
32、allel 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 to 63.50, incl 0.76 Over 63.50 to 76.20, incl
33、0.89 Over 76.20 to 127.00, incl 1.14 3.4.4.4 Decarburization of tubing that 3.4.4.1 or 3.4.4.2 is not applicable shall be not greater than shown in Table 5. Table 5A - Maximum decarburization, inch/pound units Nominal Wall Thickness Inches Total Depth of Decarburization Inches ID Total Depth of Deca
34、rburization Inches 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 1.000 0.020 0.040 Table 5B - Maximum decarburization, SI units Nominal Wall Thickness Milli
35、meters 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 to 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 SAE INTERNAT
36、IONAL AMS6257F Page 6 of 10 3.4.4.5 Decarburization shall be evaluated by one of the two methods of 3.4.4.5.1 or 3.4.4.5.2. 3.4.4.5.1 Metallographic Method A cross section taken perpendicular to the surface shall be prepared, etched, and visually examined metallographically at a magnification not to
37、 exceed 100X. Optical indications of decarburiztion shall not show a layer of complete (ferrite) or partial decarburization exceeding the limits of Tables 4 or 5. 3.4.4.5.2 Hardness Traverse Method The total depth of decarburization shall be determined by a traverse method using microindentation har
38、dness 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 as the perpendicular distance from the surface to the d
39、epth 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 Tables 4 or 5. 3.4.4.5.3 When determining the depth of dec
40、arburization, 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. 3.4.4.5.4 In case of dispute, the total depth of decarburization determined using the
41、microindentation hardness traverse method shall govern. 3.4.5 Response to Heat Treatment of Bars, Forgings, and Tubing Specimens shall conform to the following requirements after being normalized by heating to 1700 F 25 F (927 C 14 C), holding at heat for 60 minutes 5 minutes, and cooling in air; ha
42、rdened by heating to 1600 F 25 F (871 C 14 C), holding at heat for 60 minutes 5 minutes, and quenching in oil; and double tempered by heating to 575 F 10 F (302 C 6 C), holding at heat for 2 hours 0.2 hours, cooling in air to room temperature, reheating to 575 F 10 F (302 C 6 C), holding at heat for
43、 2 hours 0.2 hours, and cooling at a rate equivalent to cooling in air. 3.4.5.1 Tensile Properties 3.4.5.1.1 Longitudinal Shall be as shown in Table 6; testing in the longitudinal direction need not be performed on product qualified by testing in the transverse direction. Table 6 - Minimum longitudi
44、nal tensile properties Property Value Tensile Strength 280 ksi (1931 MPa) Yield Strength at 0.2% Offset 230 ksi (1586 MPa) Elongation in 4D 8% Reduction of Area 30% SAE INTERNATIONAL AMS6257F Page 7 of 10 3.4.5.1.2 Transverse Shall be as shown in Table 7, determined on specimens selected and prepare
45、d in accordance with AMS2310 for premium aircraft-quality steels. Table 7A - Transverse tensile properties, inch/pound units Nominal Cross-Sectional Area Square Inches Tensile Strength ksi min Tensile Strength ksi max Yield Strength at 0.2% Offset ksi, min Reduction of Area %, min Average Reduction
46、of Area %, min Individual Value Up to 100, incl 280 305 230 30 25 Over 100 to 144, incl 280 305 230 25 20 Over 144 280 305 230 20 15 Table 7B - Transverse tensile properties, SI units Nominal Cross-Sectional Area Square Centimeters Tensile Strength MPa min Tensile Strength MPa max Yield Strength at
47、0.2% Offset MPa, min Reduction of Area %, min Average Reduction of Area %, min Individual Value Up to 645, incl 1931 2103 1586 30 25 Over 645 to 929, incl 1931 2103 1586 25 20 Over 929 1931 2103 1586 20 15 3.5 Quality The product, as received by purchaser, shall be uniform in quality and condition,
48、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, except that a maximum average frequency (F) rating of 0.10 and a maximum severity (S) rating of 0.20 shall apply. 3.5.2 Bars and mec
49、hanical tubing shall be free from seams, laps, tears, and cracks after removal of the standard stock removal allowance in accordance with AS1182. 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.
