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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 therefr
2、om, 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 2007 SAE International All rights reserved. No part of this publication may
3、 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) Fa
4、x: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS:http:/www.sae.org Aluminum Alloy, 7178-T76, Alclad Plate and Sheet, Improved Exfoliation Resistant UNS A87178 RATIONALE AMS-QQ-A-250/22B has been designated Noncurrent because alloy 7178 is not recommended for new designs. NONCURRENT NOTI
5、CE This specification has been declared “NONCURRENT” by the Aerospace Materials Division, SAE, as of March 2007. It is recommended, therefore, that this specification not be specified for new designs. “NONCURRENT” refers to those specifications which have previously been widely used and which may be
6、 required for production or processing of existing designs in the future. The Aerospace Materials Division, however, does not recommend these specifications for future use in new designs. “NONCURRENT” specifications are available from SAE upon request. AEROSPACE MATERIAL SPECIFICATION AMS-QQ-A-250/2
7、2B IssuedAUG 1997 RevisedSEP 1998 NoncurrentMAR 2007 Superseding AMS-QQ-A-250/22A Copyright SAE International Provided by IHS under license with SAELicensee=Defense Contract Mgmt Command/5935922100 Not for Resale, 05/23/2007 21:50:25 MDTNo reproduction or networking permitted without license from IH
8、S -,-,- 免费标准下载网( w w w . f r e e b z . n e t ) 免费标准下载网( w w w . f r e e b z . n e t ) 无需注册, 即可下载 AMS-QQ-A-250/22BSAEAMS-QQ-A-250/22B - 2 - NOTICE This document has been taken directly from Federal Specification QQ-A-250/22A and contains only minor editorial and format changes required to bring it in
9、to conformance with the publishing requirements of SAE technical standards. The original Federal Specification was adopted as an SAE standard under the provisions of the SAE Technical Standards Board (TSB) Rules and Regulations (TSB 001) pertaining to accelerated adoption of government specification
10、s and standards. TSB rules provide for (a) the publication of portions of unrevised government specifications and standards without consensus voting at the SAE Committee level, (b) the use of the existing government specification or standard format, and (c) the exclusion of any qualified product lis
11、t (QPL) sections. The complete requirements for procuring 7178 aluminum alloy alclad plate and sheet for improved exfoliation resistance described herein shall consist of this document and the latest issue of AMS-QQ-A-250. Copyright SAE International Provided by IHS under license with SAELicensee=De
12、fense Contract Mgmt Command/5935922100 Not for Resale, 05/23/2007 21:50:25 MDTNo reproduction or networking permitted without license from IHS -,-,- 免费标准下载网( w w w . f r e e b z . n e t ) 免费标准下载网( w w w . f r e e b z . n e t ) 无需注册, 即可下载 AMS-QQ-A-250/22BSAEAMS-QQ-A-250/22B - 3 - 1. SCOPE AND CLASSIF
13、ICATION: 1.1Scope: This specification covers the specific requirements for improved exfoliation resistant alclad aluminum alloy 7178-T76 sheet and -T7651 plate. The general requirements are covered in AMS-QQ-A-250. The plate and sheet covered by this specification shall be an integral composite prod
14、uct consisting of a heat-treatable aluminum alloy (7178) core with thin layers of an aluminum alloy (7072) anodic to the core and of approximately equal thickness, bonded to both surfaces 1.2Classification: Sheet shall be furnished only in the T76 temper and plate shall be furnished only in the T765
15、1 temper, as specified (See 6.2). Definitions of these tempers are in accordance with AMS-QQ-A-250 and as follows: T76-Solution heat-treated and artificially aged sufficient to produce required improved resistance to exfoliation and stress-corrosion cracking. T7651-Solution heat-treated, stress reli
16、eved by stretching to produce a permanent set of 2 percent nominal but not less than 1-1/2 nor more than 3 percent, and artificially aged sufficient to produce improved resistance to exfoliation and stress-corrosion cracking. Plate shall receive no further straightening after stretching. 2. APPLICAB
17、LE DOCUMENTS: See AMS-QQ-A-250. 3. REQUIREMENTS: 3.1Chemical Composition: The chemical composition of the core ingots or slabs and of the cladding plates used for the manufacture of the clad plates and sheets shall conform to the requirements specified in Table I for core and cladding, respectively.
18、 Copyright SAE International Provided by IHS under license with SAELicensee=Defense Contract Mgmt Command/5935922100 Not for Resale, 05/23/2007 21:50:25 MDTNo reproduction or networking permitted without license from IHS -,-,- 免费标准下载网( w w w . f r e e b z . n e t ) 免费标准下载网( w w w . f r e e b z . n e
19、 t ) 无需注册, 即可下载 AMS-QQ-A-250/22BSAEAMS-QQ-A-250/22B - 4 - 3.2Mechanical Properties: Mechanical properties perpendicular to the direction of final rolling, except for material under 9 inches in width, shall conform to the requirements of Table II for the temper specified. For material under 9 inches
20、in width, the mechanical properties parallel to the direction of final rolling shall conform to the requirements of Table II for the temper specified. TABLE I. Chemical Composition 1/ Composition ElementCore (7178) Percent Cladding (7072) Percent MinimumMaximumMinimumMaximum Zinc6.37.30.81.3 Magnesi
21、um2.43.1-0.10 Copper1.62.4-0.10 Chromium0.180.35- Manganese-0.30-0.10 Iron-0.50-2/ Silicon-0.40-2/ Titanium-0.20- Other Elements, each-0.05-0.05 Other Elements, total-0.15-0.15 AluminumRemainderRemainder 1/ Analysis shall routinely be made only for the elements specifically mentioned in Table I. If,
22、 however, the presence of other elements is indicated or suspected in amounts greater than the specified limits, further analysis shall be made to determine that these elements are not present in excess of specified limits. 2/ Iron plus silicon 0.7 percent maximum. Copyright SAE International Provid
23、ed by IHS under license with SAELicensee=Defense Contract Mgmt Command/5935922100 Not for Resale, 05/23/2007 21:50:25 MDTNo reproduction or networking permitted without license from IHS -,-,- 免费标准下载网( w w w . f r e e b z . n e t ) 免费标准下载网( w w w . f r e e b z . n e t ) 无需注册, 即可下载 AMS-QQ-A-250/22BSAE
24、AMS-QQ-A-250/22B - 5 - 3.3Cladding Thickness: 3.3.1Thickness of Cladding Plates: The aluminum alloy (7072) plates that are bonded to the two sides of the aluminum alloy (7178) ingot or slab to form a composite that is to be rolled to the finished thickness shall each have a thickness not less than t
25、hat specified in Table III. 3.3.2Average Thickness of Cladding: When specified (See 6.2), the average cladding thickness of the finished sheet or plate shall be determined. Samples, examined in accordance with AMS-QQ-A-250, shall show an average of cladding on each side as specified in Table III. TA
26、BLE II. Mechanical Properties Temper Thickness Inches Tensile Strength, ksi minimum Yield Strength at 0.2 percent Offset, ksi minimum Elongation in 2 inches or 4 times D. percent mini- mum 2/ 3/ T76 1/0.045-0.18771.060.08 0.188-0.24973.061.08 T76510.250-0.49972.060.08 0.500-1.00073.062.06 1/ Mechani
27、cal property requirements for sheet under 0.045 inch in thickness are subject to inquiry. 2/ Not required for material 1/2-inch and under in width. 3/ D represents specimen diameter. TABLE III. Cladding Thickness Thickness of Finished Plate or Sheet in inches Nominal Cladding Thickness per Side; per
28、cent of Composite Thickness Average Minimum Cladding Thickness per Side on Finished Plate or Sheet; percent of plate or sheet thickness Under 0.0634.03.2 0.063 thru 0.1872.52.0 0.188 and over 1/1.51.2 1/ For plate 0.500 inch and over, the average cladding thickness per side shall have a maximum valu
29、e of 3 percent of the plate thickness. Copyright SAE International Provided by IHS under license with SAELicensee=Defense Contract Mgmt Command/5935922100 Not for Resale, 05/23/2007 21:50:25 MDTNo reproduction or networking permitted without license from IHS -,-,- 免费标准下载网( w w w . f r e e b z . n e
30、t ) 免费标准下载网( w w w . f r e e b z . n e t ) 无需注册, 即可下载 AMS-QQ-A-250/22BSAEAMS-QQ-A-250/22B - 6 - 3.4Exfoliation and Stress-Corrosion Cracking: Material in the T76 and the T7651 tempers when tested in accordance with 4.2.1 and 4.2.2 shall show neither exfoliation corrosion equivalent to or in excess o
31、f that depicted in Figure 2 of ASTM G 34-72 for Category B nor stress-corrosion cracking susceptibility beyond the acceptance criteria detailed in 4.2.2.5. 3.4.1Lot Acceptance Control Criteria for T76 and T7651 Tempers: Susceptibility to exfoliation and stress-corrosion cracking for each inspection
32、lot of T76 and T7651 temper material shall be determined by the following control criteria (See 4.1.2 and 4.2.2): 3.4.1.1Determine mechanical properties and electrical conductivity. 3.4.1.2If the conductivity is 38 percent IACS or higher, and the tensile properties meet the minimum limits herein, th
33、e material is acceptable. 3.4.1.3If the conductivity is at least 35 percent IACS but less than 38 percent IACS, the material shall be tested as specified or reprocessed. 3.4.1.4If the conductivity is below 35 percent IACS, the material is not acceptable and must be reprocessed. 3.5Internal Defects:
34、Unless otherwise specified (See 6.2), plate shall be ultrasonically inspected (See AMS-QQ-A-250). Acceptance limits shall be as specified in Table IV. TABLE IV. Ultrasonic Discontinuity Acceptance Limits 1/ Thickness Inches Maximum Weight per Piece pounds Discontinuity Class 2/ 0.500 thru 1.0002,000
35、B 1/ Discontinuities in excess of those listed in Table IV may be allowed, subject to approval of the procuring activity, if it is established that they will be removed by machining or that they are in non-critical areas. 2/ The discontinuity class limits are defined in MIL-I-8950. Copyright SAE Int
36、ernational Provided by IHS under license with SAELicensee=Defense Contract Mgmt Command/5935922100 Not for Resale, 05/23/2007 21:50:25 MDTNo reproduction or networking permitted without license from IHS -,-,- 免费标准下载网( w w w . f r e e b z . n e t ) 免费标准下载网( w w w . f r e e b z . n e t ) 无需注册, 即可下载 AM
37、S-QQ-A-250/22BSAEAMS-QQ-A-250/22B - 7 - 3.6Marking: In addition to the marking required in FED-STD-184, plate and sheet shall be identified by an inspection lot number in at least one location on each piece. 4. QUALITY ASSURANCE PROVISIONS: See AMS-QQ-A-250 and the following: 4.1Sampling: 4.1.1For E
38、xfoliation and Stress-Corrosion Cracking Tests: Two samples shall be taken for each 4,000 pounds or less of the first three production lots for each size range of sheet and plate listed in Table II. Thereafter, surveillance testing shall be performed on at least one sample per month for each size ra
39、nge of sheet and plate produced during that month which had previously been produced with acceptable exfoliation resistance. The surveillance test sample shall be taken from an inspection lot which has met the requirements of 3.4.1.2. Samples as above shall be taken for stress-corrosion cracking tes
40、t when thickness permit (See 4.2.2). 4.1.2For Mechanical Property and Conductivity Tests: Sampling shall be in accordance with AMS-QQ-A-250 for mechanical property tests. Mechanical properties and conductivities shall be determined on the same samples (See 4.2.3). Conductivity shall be determined pr
41、ior to testing for mechanical properties. 4.2Tests: 4.2.1Exfoliation Corrosion Test: Test shall be performed in accordance with ASTM G 34-72. Full thickness specimens of sheet and plate large enough to provide visual assessment of attack may be used; however, for all materials 0.100 inch or more in
42、thickness, 10 percent of the thickness shall be removed by machining one surface. The machined surface shall be evaluated. 4.2.2Stress-Corrosion Cracking Test: Stress-corrosion cracking tests shall be performed on plate 0.75 inch and over in thickness as follows: 4.2.2.1Specimens: Specimens shall be
43、 selected in a manner such as to permit application of the specific tension stress in the short-transverse direction. Specimens shall be C-Rings as described in Method 823 of FED-STD-151 or in ASTM G 38. 4.2.2.2Exposure Period: Exposure shall be for thirty (30) days. 4.2.2.3Tension Stress: The tensi
44、le stress applied in the short-transverse direction (perpendicular to grain flow) shall be 25.0 ksi and the specimen shall be held at constant strain. Copyright SAE International Provided by IHS under license with SAELicensee=Defense Contract Mgmt Command/5935922100 Not for Resale, 05/23/2007 21:50:
45、25 MDTNo reproduction or networking permitted without license from IHS -,-,- 免费标准下载网( w w w . f r e e b z . n e t ) 免费标准下载网( w w w . f r e e b z . n e t ) 无需注册, 即可下载 AMS-QQ-A-250/22BSAEAMS-QQ-A-250/22B - 8 - 4.2.2.4Exposure Procedure: The stressed specimen shall be exposed to a 3.5 percent salt solu
46、tion prepared by dissolving reagent grade sodium chloride (NaCl) in distilled or deionized ASTM D 1193, Type II, water. The pH of the solution shall be 6.4 to 7.2. The solution temperature shall be 75 F 2, air temperature shall be 80 F 2, and with a relative humidity of 45 percent 6. The alternate i
47、mmersion cycle shall consist of 10 minutes immersion in solution and 50 minutes in air, with sufficient circulation to dry the specimens slowly before the next immersion. 4.2.2.5Stress-Corrosion Test Results: After 30 day exposure, the specimen shall exhibit no visual evidence of stress-corrosion cr
48、acking. Any highly directional attack which is suspected of concealing a stress-corrosion crack shall be cross sectioned and examined metallographically. An example of stress-corrosion cracking is shown in Figure 1. Figure 2 illustrates pitting type attack which does not constitute failure. 4.2.3Electrical Conductivity Tests: The conductivity shall be determined by taking three electrical conductivity readings at random on each sample. For thicknesses under 0.100 inch, the conductivity shall be determined on the surface after removal