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 entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, 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 2006 SAE InternationalAll rights reserved. No part of this publication may be
3、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)Fax: 724
4、-776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgAEROSPACE STANDARDAS4726Issued 1995-10Reaffirmed 2006-10Superseding AS1371Nuts, Self-Locking, UNS S66286Classification: 220 ksi/850 FProcurement SpecificationFSC 5310RATIONALEThis document has been reaffirmed to comply with the
5、SAE 5-year Review policy.1. SCOPE:1.1 Type:This specification establishes the requirements for self-locking nuts, wrenching type (i.e., hexagon, double hexagon, and spline drive), made of a corrosion and heat resistant steel of the type identified under the Unified Numbering System as UNS S66286.1.1
6、.1 Classification:a. 220 ksi minimum tensile strength at room temperatureb. 850 F maximum test temperature of parts.1.2 Application:Primarily for use in aerospace propulsion systems in temperatures up to approximately 850 F where nuts are used with bolts capable of developing 220 ksi axial tensile s
7、trength at room temperature, and having UNJ thread form.2. REFERENCES:2.1 Applicable Documents:The following publications form a part of this specification to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other documents shall be the issue in
8、effect on the date of the purchase order. In the event of conflict between the text of this specification and references cited herein, the text of this specification takes precedence. Nothing in this specification, however, supersedes applicable laws and regulations unless a specific exemption has b
9、een obtained.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4726 - 2 -2.1.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.AMS 2403 Plating, Nickel, Ge
10、neral PurposeAMS 2418 Plating, CopperAMS 2759/3 Heat Treatment of Precipitation Hardening, Corrosion Resistant and Maraging Steel PartsAMS 5731 Steel Bars, Forgings, Tubing, and Rings, Corrosion and Heat Resistant, 15Cr 25.5Ni 1.3Mo 2.1Ti 0.006B O.30V, Consumable Electrode Melted, 1800 F (980 C) Sol
11、ution Heat TreatedAMS 5732 Steel Bars, Forgings, Tubing, and Rings, Corrosion and Heat Resistant, 15Cr 25.5Ni 1.2No 2.1Ti 0.006B 0.30V, Consumable Electrode Melted, 1800 F (980 C) Solution and Precipitation Heat TreatedAMS 5734 Steel Bars, Forgings, and Tubing, Corrosion and Heat Resistant, 15Cr 25.
12、5Ni 1.3Mo 2.1Ti 0.006B 0.30V, Consumable Electrode Melted, 1650 F (900 C) Solution Heat TreatedAMS 5737 Steel Bars, Forgings, and Tubing, Corrosion and Heat Resistant, 15Cr 25.5Ni 1.3Mo 2.1Ti 0.006B 0.30V, Consumable Electrode Melted, 1650 F (900 C) Solution and Precipitation Heat TreatedAS954 Desig
13、n Data and Standardization of Thin Wall 12-Point Sockets and Box Wrenches for Aerospace Engine UseAS1310 Fastener Torque for Threaded Applications, Definitions of AS1701 Lubricant, Solid Dry FilmAS7477 Bolts and Screws, Steel, Corrosion and Heat Resistant, Upset Headed, Heat Treated, Roll Threaded,
14、1800F Solution and Precipitation Heat Treated2.1.2 U.S. Government Publications: Available from DODSSP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA, 19111-5094.QQ-P-35 Passivation Treatments for Corrosion Resistant SteelMIL-L-7808 Lubricating Oil, Aircraft Turbine E
15、ngine, Synthetic Base MIL-S-8879 Screw Threads, Controlled Radius Root With Increased Minor Diameter; General Specification ForMIL-W-8982 Wrenches, Splined, High Strength, Thin Wall, General Specification ForMIL-STD-1312-7 Fastener Test Methods, Method 7, VibrationMIL-STD-1312-8 Fastener Test Method
16、s, Method 8, Tensile Strength2.1.3 ASTM Publications: Available from ASTM, 1916 Race Street, Philadelphia, Pa 19103-1187.ASTM E 1417 Liquid Penetrant ExaminationASTM D 3951 Commercial Packaging2.1.4 ANSI Publication: Available from ANSI, 11 West 42nd Street, New York, NY 10036-8002.ANSI/ASME B46.1 S
17、urface Texture (Surface Roughness, Waviness, and Lay)Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4726 - 3 -2.2 Definitions:Refer to AS1310 for definitions related to fastener torque.DEFECTI
18、VE: A unit of product which contains one or more defects.BURR: A rough edge or ridge left on the metal due to a cutting, grinding, piercing or blanking operation.TIGHT BURR: A burr closely compacted and binding in the periphery of a part without any loose ends and is within the dimensional limits of
19、 the part.PRODUCTION LOT: Shall consist of finished nuts fabricated by the same process from a single heat of alloy, heat treated at the same time to the same specified condition, produced as one continuous run, and submitted for vendors inspection at the same time.INSPECTION LOT: Shall consist of n
20、uts from a single production lot, of the same part number.2.3 Unit Symbols: degree, angularC degree CelsiusF degree Fahrenheit% percent (1% = 1/100)HRC hardness, Rockwell C scalelbf pound-forcelbf-in pound-force inch, torqueksi kips (1000 pounds) per square inchcpm cycles per minutesq in square inch
21、in Ra microinch, roughness average3. TECHNICAL REQUIREMENTS:3.1 Material:Shall be a corrosion and heat resistant steel, AMS 5731, AMS 5732, AMS 5734, or AMS 5737 bars or forgings. as specified on the part drawing.3.2 Design:Finished (completely manufactured) parts shall conform to the following requ
22、irements:3.2.1 Dimensions: The dimensions of finished parts after all processing, shall conform to the part drawing, unless otherwise specified. Dimensions shall apply before coating with solid dry film lubricant.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo repr
23、oduction or networking permitted without license from IHS-,-,-SAE AS4726 - 4 -3.2.1.1 Bearing Surface Squareness: The bearing surface shall be square with the thread pitch cylinder axis within the limits specified on the part drawing. Bearing surface shall not be convex. Bearing surface squareness s
24、hall be tested on an expanding type thread plug gage that positions on the nut thread pitch cylinder (thus, establishing the datum axis of nut thread) with a dial indicator stylus positioned on the nut bearing surface near the minimum bearing diameter. Indicator readings are taken during circular an
25、d radial stylus movements over the bearing surface. The squareness requirement shall apply to the complete bearing surface of the nut. The nuts to be inspected shall permit at least three full threads of engagement on the thread gage of the test fixture; coating shall be stripped to meet this requir
26、ement.3.2.1.2 Geometric Tolerances: Part features shall be within the geometric tolerance specified on the part drawing when tested by conventional measuring methods, except for the measurement method for bearing surface perpendicularity as in 3.2.1.1.3.2.2 Surface Texture: Surface texture of finish
27、ed parts, prior to coating, shall conform to the requirements on the part drawing, determined in accordance with ANSI/ASME B46.1.3.2.3 Threads: UNJ thread profile having dimensions and tolerances in accordance with MIL-S-8879.3.2.3.1 Thread Relief: The entering end of the thread at the bearing surfa
28、ce shall be relieved by methods, such as, countersinking or counterboring to remove the thread feather edge, and the top of the nut shall be countersunk as specified on the part drawing.3.2.3.2 Coating Allowance: Unless otherwise specified on the part drawing, internal thread coating allowance shall
29、 be as specified in MIL-S-8879 before forming the self-locking feature.3.2.3.3 Forming Self-Locking Feature: The upper threaded portion shall be formed out-of-round in any manner which provides self-locking nuts meeting the locking torque requirements of this specification. The coated nut shall perm
30、it assembly of a test bolt, as in 3.8, freely with the fingers for a minimum of one turn.3.2.4 Construction: Each nut shall be of the prevailing torque-type, self-contained, all metal unit, including the self-locking feature. The locking feature shall not operate by means of separate movement and sh
31、all not depend upon pressure on the bearing surface for the locking action. Tool marks resulting from producing the self-locking feature shall blend smoothly without abrupt change.3.3 Heat Treatment and Fabrication:Parts shall be fabricated by forging or machining and heat treated in accordance with
32、 AMS 2759/3 for A286, aged after cold working to meet the tensile strength requirements of this specification and the part drawing.3.3.1 Passivation Treatment: Finished parts that are not plated as in 3.5.1, shall before coating as in 3.5.2 be passivate treated and copper sulfate tested in accordanc
33、e with QQ-P-35.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4726 - 5 -3.4 Product Marking:Each part shall be marked for identification as specified on the part drawing. Depressed characters
34、shall have a rounded root form, depressed 0.010 inch maximum.3.5 Coating:3.5.1 Plating: Before coating with solid dry film lubricant, nuts may be copper flash plated per AMS 2418-1 or nickel flash plated per AMS 2403, 0.0001 inch minimum thickness on thread and bearing surface; other surfaces are op
35、tional to plate.3.5.2 Coating: After flash plating as in 3.5.1, parts shall be coated with MoS2dry film lubricant in accordance with AS1701, Type VI, unless otherwise specified on the part drawing.3.6 Quality:Parts shall be uniform in quality and condition, free from burrs (tight burrs may be accept
36、able if part performance is not affected), foreign materials, and from imperfections detrimental to the usage of the part.3.6.1 Fluorescent Penetrant Inspection: Prior to coating as in 3.5, parts shall be subjected to fluorescent penetrant inspection in accordance with ASTM E 1417, Type I, Sensitivi
37、ty Level 2. Acceptance criteria of surface discontinuities shall be in accordance with Appendix F.3.7 Product Performance Tests:Refer to Tables 5 and 6 for details of sample sizes for Acceptance Test Plan and Qualification Approval Test Plan.3.7.1 Axial Tensile Strength: Nuts shall withstand the min
38、imum tensile load as specified in Table 1 without rupture, stripping or appearance of cracks when tested as follows:3.7.1.1 As Received Condition at Room Temperature: Nuts in as received condition tested in accordance with MIL-STD-1312-8, using alloy steel test bolts hardened and tempered to 46 HRC
39、minimum, and having MIL-S-8879 threads, shall withstand the axial tensile load specified in Table 1.3.7.1.2 After Bake, at Room Temperature: Prior to testing, the nut shall be assembled on a test bolt as in 3.8 with at least two thread pitches protruding through the nut and baked for 6 hours + 0.25
40、hour at 850 F 15 F and then cooled to room temperature. The nut shall then be removed from the bolt and assembled onto a test bolt as in 3.7.1.1; a new test bolt shall be used for each axial tensile test. Nuts shall be tested, after baking, at room temperature in accordance with MIL-STD-1312-8 and s
41、hall withstand the axial tensile load in Table 1.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4726 - 6 -3.7.1.3 The axial tensile load for thread sizes not shown in Table 1 may be calculated
42、 from the following equation:(Eq. 1)(Eq. 2)where:A = Tensile stress area in thread, square inchF = Axial tensile load, minimum, lbfd2 = Pitch diameter, maximum, external thread, inchd3= Minor (root) diameter, maximum, external thread, inch220 = ksi applied at area A3.7.2 Wrench Torque: Nuts with hex
43、agon, double hexagon or spline drive wrenching features shall be tested as specified in Appendix A and shall withstand the wrench torques specified in Table 2 applied through 12 engagement cycles without any permanent deformation which can interfere with the use of socket wrenches conforming to AS95
44、4 for hexagon and double hexagon drives, and MIL-W-8982 for spline drive wrenching feature. The dry film lubricant may be stripped from the nuts before performing the wrench torque test.TABLE 1 - Axial Tensile LoadNutThread SizeAxial Tensile Loadat Room Temperaturelbf minimum0.164 -32UNJC-3B 34100.1
45、64 -36UNJF-3B 35600.190 -32UNJF-3B 48200.250 -28UNJF-3B 86800.3125-24UNJF-3B 137900.375 -24UNJF-3B 206200.4375-20UNJF-3B 279300.500 -20UNJF-3B 373400.5625-18UNJF-3B 473600.625 -18UNJF-3B 59400Addd=0 7854 232322.()(/)FAx x= 220 103Copyright SAE International Provided by IHS under license with SAENot
46、for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AS4726 - 7 -3.7.3 Permanent Set: Nuts shall be tested as specified in Appendix B and shall not exceed the maximum permissible locking torque or be less than the minimum breakaway torque values specified in Table 3, Co
47、lumns (3) and (1), respectively. The bolt or mandrel shall protrude through the top of the nut a minimum of three full thread pitches.3.7.4 Reusability Test at Room Temperature, After Bake: Nuts shall be tested for five consecutive cycles as specified in Appendix C, loading initially to 110 ksi in a
48、ccordance with 3.7.4.3. The assembly shall be heated in a furnace to 850 F 15 F for 6 hours 0.25 hour, removed from the furnace and cooled to room temperature.3.7.4.1 Wrenching and Reference Recording: Nuts shall be wrenched by turning the nut relative to the fixture. The wrenchability of the tested
49、 nuts shall permit assembly using a standard wrench. For reference information, the assembly and breakloose torques shall be recorded for each heat cycle.3.7.4.2 Locking Feature Torque Requirements: Nuts tested as in 3.7.4 shall conform to the minimum breakaway torque in Table 3, Column (1), for each cycle. The self-locking torque shall be measured on installation and rem
