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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 theref
2、rom, 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 2008 SAE International All rights reserved. No part of this publication ma
3、y 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: 724-776-4970 (outside USA)
4、Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org AMS 4988A AEROSPACE MATERIAL SPECIFICATION Issued 2003-04 Revised 2008-01 Superseding AMS 4988 Titanium Alloy Sheet, Strip, and Plate 6Al - 6V - 2Sn Solution Heat Treated (Composition similar to UNS R56620) RATIONALE
5、AMS 4988A results from a Five Year Review and update of this specification. 1. SCOPE 1.1 Form This specification covers a titanium alloy in the form of sheet, strip, and plate. 1.2 Application This material has been used typically for parts to be formed or machined in the solution heat treated condi
6、tion and subsequently precipitation heat treated requiring high strength-to-weight ratio and stability up to 550 F (288 C) in the precipitation heat treated condition, but usage is not limited to such applications. 1.3 Certain processing procedures and service conditions may cause these products to
7、become subject to stress- corrosion cracking; ARP982 recommends practices to minimize such conditions. 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
8、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 Commonw
9、ealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AMS 2242 Tolerances, Corrosion and Heat-Resistant Steel, Iron Alloy, Titanium, and Titanium Alloy Sheet, Strip, and Plate AMS 2249 Chemical Check Analysis Limits, Titanium an
10、d Titanium Alloys AMS 2631 Ultrasonic Inspection of Titanium Alloys AMS 2750 Pyrometry AMS 2809 Identification, Titanium and Titanium Alloy Wrought Products SAE AMS 4988A - 2 - ARP982 Minimizing Stress-Corrosion Cracking in Wrought Titanium Alloy Products 2.2 ASTM Publications Available from ASTM In
11、ternational, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM E 8 Tension Testing of Metallic Materials ASTM E 112 Determining Average Grain Size ASTM E 290 Bend Testing of Material for Ductility ASTM E 384 Microindentation Hardness of Mat
12、erials ASTM E 1409 Determination of Oxygen and Nitrogen in Titanium and Titanium Alloys by the Inert Gas Fusion Technique ASTM E 1447 Determination of Hydrogen in Titanium and Titanium Alloys by the Inert Gas Fusion Thermal Conductivity/Infrared Detection Method ASTM E 1941 Determination of Carbon i
13、n Refractory and Reactive Metals and Their Alloys ASTM E 2371 Analysis of Titanium and Titanium Alloys by Atomic Emission Plasma Spectrometry 3. TECHNICAL REQUIREMENTS 3.1 Composition Shall conform to the percentages by weight shown in Table 1; carbon shall be determined in accordance with ASTM E 19
14、41, hydrogen in accordance with ASTM E 1447, oxygen and nitrogen in accordance with ASTM E 1409, and other elements in accordance with ASTM E 2371. Other analytical methods may be used if acceptable to the purchaser. TABLE 1 - COMPOSITION Element min max Aluminum 5.00 6.00 Vanadium 5.00 6.00 Tin 1.5
15、0 2.50 Iron 0.35 1.00 Copper 0.35 1.00 Oxygen - 0.20 Carbon - 0.05 Nitrogen - 0.04 (400 ppm) Hydrogen - 0.015 (150 ppm) Yttrium (3.1.1) - 0.005 ( 50 ppm) Other Elements each (3.1.1) - 0.10 Other Elements, total (3.1.1) - 0.40 Titanium remainder 3.1.1 Determination not required for routine acceptance
16、. 3.1.2 Check Analysis Composition variations shall meet the applicable requirements of AMS 2249. 3.1.3 Sample size, when using ASTM E 1447, may be as large as 0.35 gram. 3.2 Melting Practice 3.2.1 Alloy shall be multiple melted. The final melting cycle shall be under vacuum. The first melt shall be
17、 made by consumable electrode, nonconsumable electrode, electron beam cold hearth, or plasma arc cold hearth melting practice. The subsequent melt or melts shall be made using vacuum arc remelting (VAR) practice with no alloy additions permitted in the last vacuum arc remelt. -,-,- SAE AMS 4988A - 3
18、 - 3.2.1.1 The atmosphere for non-consumable electrode melting shall be vacuum or shall be argon and/or helium at an absolute pressure not higher than 1000 mm of mercury. 3.2.1.2 The electrode tip for nonconsumable electrode melting shall be water-cooled copper. 3.3 Condition The product shall be su
19、pplied in the following condition: 3.3.1 Sheet and Strip Hot rolled, with or without subsequent cold reduction, solution heat treated, descaled, and leveled, having a surface appearance comparable to a commercial corrosion-resistant steel No. 2D finish (See 8.3). 3.3.2 Plate Hot rolled, solution hea
20、ted, and flattened, having a surface appearance comparable to a commercial corrosion-resistant steel No. 1 finish (See 8.2). Plate product shall be produced using standard industry practices designed strictly for the production of plate stock to the procured thickness. Bar, billet, forgings, or forg
21、ing stock shall not be supplied in lieu of plate. 3.4 Heat Treatment The product shall be solution heat treated as follows; pyrometry shall be in accordance with AMS 2750: 3.4.1 Sheet, strip and plate shall be solution heat treated by heating to a temperature within the range 1550 to 1700 F (843 to
22、927 C), holding at selected temperature within 25 F ( 14 C) for 2 to 60 minutes, and quenching in agitated water. Air cooling may be applied in thin material. 3.5 Properties Product shall conform to the following requirements: 3.5.1 As Solution Heat Treated 3.5.1.1 Tensile Properties Shall be as spe
23、cified in Table 2, determined in accordance with ASTM E 8 with the rate of strain maintained at 0.003 to 0.007 inch/inch/minute (0.003 to 0.007 mm/mm/minute) through the yield strength and then increased so as to produce failure in approximately one additional minute. When a dispute occurs between p
24、urchaser and vendor over the yield strength values, a referee test shall be performed on a machine having a strain rate pacer; using a rate of 0.005 inch/inch/minute (0.005 mm/mm/minute) through the yield strength and a minimum cross head speed of 0.10 inch (2.5 mm) per minute above the yield streng
25、th. TABLE 2A - TENSILE PROPERTIES, INCH/POUND UNITS (SEE 8.2) Nominal Thickness Inch Tensile Strength ksi Yield Strength at 0.2% Offset ksi, max Elongation in 2 Inches or 4D %, min Up to 0.1875, excl (3.5.1.1.1) 160 10 (3.5.1.1.2) TABLE 2B - TENSILE PROPERTIES, SI UNITS (SEE 8.2) Nominal Thickness M
26、illimeters Tensile Strength MPa Yield Strength at 0.2% Offset MPa, max Elongation in 50.8 mm or 4D %, min Up to 4.76, excl (3.5.1.1.1) 1103 10 (3.5.1.1.2) SAE AMS 4988A - 4 - 3.5.1.1.1 Spread between tensile strength and yield strength shall be 15 ksi (103 MPa) minimum. 3.5.1.1.2 For thickness under
27、 0.025 inch (0.64 mm), elongation values shall be as agreed upon. 3.5.1.2 Bending Product under 0.1875 inch (4.762 mm) in nominal thickness, shall have a test sample prepared nominally 0.750 inch (19.06 mm) in width, with its axis of bending parallel to the direction of rolling. The sample shall be
28、bend tested in conformance with the guided bend test defined in ASTM E 290 through an angle of 105 degrees. The test fixture supports shall have a contact radius 0.010 minimum, and the plunger shall have a radius equal to the bend factor shown in Table 3 times the nominal thickness. Examination of t
29、he bent sample shall show no evidence of cracking when examined at 15 to 25X magnification. TABLE 3 - BEND FACTOR Nominal Thickness Inch Nominal Thickness Millimeters Bend Factor Up to 0.070, excl Up to 1.78, excl 4 0.070 to 0.1875, incl 1.78 to 4.762, incl 4.5 3.5.1.3 Microstructure Shall be that s
30、tructure resulting from processing within the alpha-beta phase field. Microstructure shall conform to 3.4.1.3.1 or 3.4.1.3.2 (See 8.5). 3.5.1.3.1 Equiaxed and/or elongated primary alpha in a transformed beta matrix with no continuous network of alpha at prior beta grain boundaries. 3.5.1.3.2 Essenti
31、ally complete field of equiaxed and/or elongated alpha with or without intergranular beta and with no continuous network of alpha at prior beta grain boundaries. 3.5.1.3.3 A microstructure showing a continuous network of alpha in prior beta grain boundaries is not acceptable. 3.5.1.4 Surface Contami
32、nation The product shall be free of any oxygen-rich layer, such as alpha case, or other surface contamination, determined as in any one of the following: 3.5.1.4.1, 3.5.1.4.2, 3.5.1.4.3, or other method acceptable to purchaser. 3.5.1.4.1 The bend test of 3.5.1.2. 3.5.1.4.2 Microscopic examination at
33、 400X minimum. 3.5.1.4.3 Hardness difference; a surface hardness more than 40 points higher than the subsurface hardness, determined in accordance with ASTM E 384 on the Knoop scale using a 200 gram load, being evidence of unacceptable surface contamination. 3.5.1.5 Average Grain Size Shall be ASTM
34、No. 6 or finer determined by comparison of a polished and etched specimen with the chart in ASTM E 112. 3.5.2 Response to Heat Treatment Product shall conform to the following requirements after being precipitation heat treated by heating to a temperature within the range of 875 to 1150 F (468 to 62
35、1 C), holding at selected temperature within 15 F (8 C) for 2 to 10 hours, and cooling in air. Precipitation heat treatment shall precede final machining of specimens. -,-,- SAE AMS 4988A - 5 - 3.5.2.1 Tensile Properties Shall be as shown in Table 4, determined in accordance with ASTM E 8 with the r
36、ate of strain maintained at 0.003 to 0.007 inch/inch/minute (0.003 to 0.007 mm/mm/minute) through the yield strength and then increased so as to produce failure in approximately one additional minute. When a dispute occurs between purchaser and vendor over the yield strength values, a referee test s
37、hall be performed on a machine having a strain rate pacer, using a rate of 0.005 inch/inch/ minute (0.005 mm/mm/minute) through the yield strength and a minimum cross head speed of 0.10 inch (2.5 mm) per minute above the yield strength. TABLE 4A - MINIMUM TENSILE PROPERTIES (SEE 8.2) Nominal Thickne
38、ss Inches Tensile Strength ksi Yield Strength at 0.2% Offset ksi Elongation in 2 in. or 4D % Up to 0.1875, incl 170 160 8 (6) (See 3.5.2.1.1) 0.1875 to 1.500, excl 170 160 8 1.500 to 2.500, excl 160 150 6 2.500 to 4.000, excl 150 140 6 TABLE 4B - MINIMUM TENSILE PROPERTIES, SI UNITS (SEE 8.2) Nomina
39、l Thickness Millimeters Tensile Strength MPa Yield Strength at 0.2% Offset MPa Elongation in 50.8 mm or 4D % Up to 4.76, incl 1172 1103 8 (6) (See 3.5.2.1.1) 4.76 to 38.10, excl 1172 1103 8 38.10 to 63.50, excl 1103 1034 6 63.50 to 101.60, excl 1034 965 6 3.5.2.1.1 Elongation value in parentheses is
40、 for transverse direction only. 3.6 Quality The product, as received by purchaser, shall be uniform in quality and condition, sound, and free from “oil cans” (See 8.4) of depth in excess of the flatness tolerances, ripples, and foreign materials and from imperfections detrimental to usage of the pro
41、duct. 3.6.1 Ultrasonic Inspection Plate 0.500 to 4.000 inch (12.70 to 101.60 mm) incl in nominal thickness shall meet Class A1 requirements of AMS 2631. 3.7 Tolerances Shall conform to all applicable requirements of AMS 2242. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection The vend
42、or 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 to perform any confirmatory testing deemed necessary to ensure that the product conforms to specified requirements. 4.2 Classifi
43、cation of Tests All technical requirements are acceptance tests and shall be performed on each heat or lot as applicable. SAE AMS 4988A - 6 - 4.3 Sampling and Testing Shall be in accordance with the following; a lot shall be all product of the same nominal size from the same heat processed at the sa
44、me time and in the same heat treatment batch. 4.3.1 Composition One sample from each heat, except that for hydrogen determinations one sample from each lot obtained after thermal and chemical processing is completed. 4.3.2 Tensile Properties, Bending, Microstructure, Surface Contamination, Average G
45、rain Size, and Tensile Properties after Precipitation Hardening At least one sample from each lot. 4.3.2.1 Specimens for tensile and notch-tensile tests of widths 9 inches (229 mm) and over shall be taken in both the longitudinal and transverse directions; for widths under 9 inches (229 mm), specime
46、ns shall be taken in the longitudinal direction. 4.3.2.2 Bend Specimens Whenever possible, the specimen shall be long enough to permit two separate bends so that each surface is tested in tension. 4.4 Reports The vendor shall provide a copy of the original material manufacturers report (material cer
47、tification) including: producer name, product form, mill produced size, and country where the metal was melted (i.e., final melt in the case of metal processed by multiple melting operations). The vendor of the product shall furnish with each shipment a report showing the results of tests for compos
48、ition of each heat and for the hydrogen content, tensile and bending properties, average grain size, and surface contamination 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, AMS 4988A,
49、 product form, size, specific aging treatment used to develop precipitation hardened properties, and quantity. 4.5 Resampling and Retesting If any specimen used in the above tests fails to meet the specified requirements, disposition of the product may be based on the results of testing three additional specimens for each original nonconforming specimen. Failure of any retest specimen to meet the specified requirements shall be cause for r