1、Designation: B 839 04Standard Test Method forResidual Embrittlement in Metallic Coated, ExternallyThreaded Articles, Fasteners, and RodInclined WedgeMethod1This standard is issued under the fixed designation B 839; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONWhen atomic hydrogen enters steels and certain other alloys, it can cause
3、 loss of ductility or loadcarrying ability or cracking (usually as submicroscopic cracks), or catastrophic brittle failures atapplied stresses well below the yield strength or even the normal design strength for the alloys. Thisphenomenon often occurs in alloys that show no significant loss in ducti
4、lity, when measured byconventional tensile tests, and is frequently referred to as hydrogen-induced delayed brittle failure,hydrogen stress cracking, or hydrogen embrittlement. The hydrogen can be introduced duringcleaning, pickling, phosphating, electroplating, autocatalytic processes, and in the s
5、ervice environmentas a result of cathodic protection reactions or corrosion reactions. Hydrogen can also be introducedduring fabrication, for example, during roll forming, machining, and drilling due to lubricantbreakdown as well as during welding or brazing operations.1. Scope1.1 This test method c
6、overs the determination of, on astatistical basis, the probability of the existence of hydrogenembrittlement or degradation in:1.1.1 A batch of barrel electroplated, autocatalytic plated,phosphated, or chemically processed threaded articles or fas-teners and1.1.2 A batch of rack plated threaded arti
7、cles, fasteners, orrod.1.2 Industrial practice for threaded articles, fasteners, androd has evolved three graduated levels of test exposure toensure reduced risk of hydrogen embrittlement (see Section 3).These levels have evolved from commercial applicationshaving varying levels of criticality. In e
8、ssence, they representthe confidence level that is required. They also represent thetime that finished goods are held before they can be shippedand used. This time equates to additional cost to the manufac-turer that may of necessity be added to the cost of the finishedgoods.1.3 This test method is
9、applicable to threaded articles,fasteners, and rod made from steel with $1000 MPa (withcorresponding hardness values of 300 HV10 kgf, 303 HB, or 31HRc) or surface hardened threaded articles, fasteners, or rod.1.4 This test method shall be carried out after hydrogenembrittlement relief heat treatment
10、 in accordance with therequirements of Guide B 850. It may also be used for assessingdifferences in processing solutions, conditions, and techniques.This test method has two main functions: first, when used witha statistical sampling plan it can be used for lot acceptance orrejection, and second, it
11、 can be used as a control test todetermine the effectiveness of the various processing stepsincluding pre- and post-baking treatments to reduce the mobilehydrogen in the articles, fasteners, or rod. While this testmethod is capable of indicating those items that are embrittledto the extent defined i
12、n Section 3, it does not guaranteecomplete freedom from embrittlement.1.5 This test method does not relieve the processor fromimposing and monitoring suitable process control.1.6 This test method has been coordinated with ISO/DIS10587 and is technically equivalent. (WarningGreat careshould be taken
13、when applying this test method. The heads ofembrittled articles, fasteners, or rod may suddenly break offand become flying projectiles capable of causing blindness orother serious injury. This hazard can occur as long as 200 h1This test method is under the jurisdiction of ASTM Committee B08 on Metal
14、licand Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 onTest Methods.Current edition approved April 1, 2004. Published April 2004. Originallyapproved in 1994. Last previous edition approved in 2003 as B 839 94 (2003).1Copyright ASTM International, 100 Barr Harbor Drive, P
15、O Box C700, West Conshohocken, PA 19428-2959, United States.after the test has started. Hence, shields or other apparatusshould be provided to avoid such injury.)NOTE 1Test Method F 1940 can be used as a process control andverification to prevent hydrogen embrittlement in fasteners covered by thiste
16、st method.NOTE 2The use of inhibitors in acid pickling baths does not neces-sarily guarantee avoidance of hydrogen embrittlement.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish
17、 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB 697 Guide for Selection of Sampling Plans for Inspectionof Electrod
18、eposited Metallic and Inorganic CoatingsF 436 Specification for Hardened Steel WashersB 850 Guide for Post-Coating Treatments of Steel for Re-ducing Risk of Hydrogen EmbrittlementF 1940 Test Method for Process Control Verification toPrevent Hydrogen Embrittlement in Plated or CoatedFasteners2.2 ISO
19、Standards:ISO/DIS 10587 Residual Embrittlement in Metallic Coated,Externally Threaded Articles, Fasteners and RodInclined Wedge Method3ISO 4519 Electrodeposited Metallic Coatings and RelatedFinishesSampling Procedures for Inspection by At-tributes42.3 Military Standard:MIL-STD-1312 Fastener Test Met
20、hods43. Terminology3.1 DefinitionsFor the purposes of this test method thefollowing definitions apply:3.1.1 batcha distinct portion of items processed collec-tively as a single group through the same identical treatmentsteps at the same time on the same rack or in the same barrel.3.1.2 embrittledwhe
21、re parts fail immediately or up to 48h in test.3.1.2.1 DiscussionThe degree to which parts within asingle plated batch or a given lot can be embrittled can varyover a wide range. The degree of embrittlement is a function ofthe concentration of atomic hydrogen in the individual parts inthe batch or l
22、ot, measured in parts per million, and in particularthat portion of the hydrogen that is mobile or free to migrate toareas of high stress concentration.3.1.3 Grade 48 proofwhere there are no failures after 48h of test.3.1.4 Grade 96 proofwhere there are no failures after 96h of test.3.1.5 Grade 200
23、proofwhere there are no failures after200 h of test.3.1.6 lota group of items processed through the same orsimilar steps at the same time or over a contiguous time periodand from the same heat of material. The lot may be brokendown into a number of batches for processing purposes andthen reassembled
24、 into the same lot.4. Summary of Test Method4.1 The threaded articles, fasteners, or rod are subjected tostress by tensioning with a mating nut after insertion through aclearance hole in a hardened rectangular wedge of steel; seeFig. 1. Additional hardened rectangular pieces of steel withparallel fa
25、ces are provided as filler plates and are inserted sothat the required length of the threaded article is placed undertest. Other loading systems and fixtures are permissible as longas the same load, angle, and exposure are created for the test.The upper surface of the wedge is ground at an angle to
26、thelower surface. The mating nut is tensioned by any means2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Av
27、ailable from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Available from Standardization Documents Order Desk, Bldg. 4, Section D,700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.FIG. 1 Example of 6 Wedge and Parallel Filler PlateB839042capabl
28、e of measuring tensile load. The torque method de-scribed in 6.4 is one such method. If the torque method oftightening is used, the fasteners are torqued to the desiredvalue, held for the minimum specified hours, and then checkedto determine if the initial torque has been maintained. Follow-ing this
29、 they are examined for embrittlement failures. SeeSection 9.NOTE 3Increasing the applied torque by a small percentage as asafety factor is not recommended.5. Significance and Use5.1 The use of this test method can significantly reduce therisk of sudden catastrophic failure of threaded articles andfa
30、steners, below their design strength, due to hydrogen em-brittlement.6. Apparatus6.1 Test Fixture comprising a hardened wedge (see Fig. 1),one or more filler plates, and a hardened washer. The hole ineach shall be as close to the major diameter of the threadedarticle, fastener, or rod being tested a
31、s practical. Excessclearance space may cause the fastener to tilt in the hole andcan result in a failure at a lower torque value.6.2 Fixture With Multiple Holes has been found useful formultiple or repetitive testing. The fixture can be readily madefrom a rectangular piece of an air hardening grade
32、of steel withone face ground to the appropriate wedge angle and hardenedto HRc60.6.3 WedgeShall have an angle as specified in Table 1.6.4 Filler Plate(s)Shall be of the same steel grade andhardness as the wedge fixture and have a thickness such that,after installation and tightening, a minimum of th
33、ree fullthreads of the test fastener will be engaged and no more thanfive full threads will extend beyond the nut.6.5 WasherShall be HRc38 to 45 and shall conform to therequirements of Specification F 436.6.6 Torque Application DeviceIf the torque method oftightening is used, the tightening torque s
34、hall be determinedusing a load measuring device capable of measuring the actualtension induced in the article, fastener, or rod as the item istightened.6.7 Torque DeterminationFive items from the test lotshall be selected at random. Each shall be assembled into theload measuring device, mated with a
35、 nut, and the nut tighteneduntil a load equal to 75 % of the ultimate tensile strength of theitem is induced. The torque required to induce this load shall bemeasured and the arithmetic average of the five measuredtorques shall be the tightening torque. Calculated torque versustension methods of tes
36、ting such as the T = KDL formula usedin MIL-STD-1313 are not sufficiently accurate for use in thistest and shall not be used.7. Sampling7.1 The document specifying this test method shall specifyan AQI level and sampling plan to be used. Guidance in theselection of sampling plans is provided in Guide
37、 B 697. Widelyused sampling plans are provided in Test Method B 602 and itsequivalent ISO 4519.7.2 A minimum sample size of 30 pieces is necessary fromeach embrittlement relief treated batch that exceeds 500 piecesplated as a single group.8. Procedure8.1 Test Item PlacementPlace the test items in th
38、e clear-ance holes with the heads positioned against the angle of thewedge. In the case of items with square, hexagonal, or similarstraight side heads, a straight side shall be placed against theangle of the wedge. In the case of elliptical or other shapedheads, the side with the minor radius of the
39、 ellipse shall beplaced against the angle of the wedge. In the case of itemswithout heads, studs, or threaded rod, one end shall be nuttedand tested as the head. When the items are threaded withdifferent pitch threads, the finer thread shall be treated as thehead. Nut the free end of the items and r
40、un them up finger-tight. No significance has been found between the start of thethread on an article in relation to the angle of the wedge.8.2 Torque ApplicationClamp the wedge device with thenutted ends facing in a convenient position in a securelyattached vice. Using a calibrated torque tool tight
41、en the nuts tothe desired torque and record the values. The wedge should beremoved from the vice and left undisturbed for the test period.See Section 3.9. Evaluation9.1 Cracks, Separated Heads, and BreakageAfter thespecified holding period is complete, examine each item forfailures such as cracks, s
42、eparated heads, and breakage. Usefinger pressure to check each head for breakage. Cracks can beidentified by examination at 103 magnification, magneticparticle inspection, or the use of a liquid dye penetrant.9.2 Relaxed TorqueFollowing the examination of thespecimens in 9.1, place the wedge in a vi
43、ce and carefully turneach mating nut, with the torque tool, in the on direction untila forward angular motion, after break loose, is noticeable.Record the torque value at break loose and compare it with theinitially recorded torque. Torque relaxation greater than 10 %shall be recorded as failure. Re
44、move the nuts and examine theitems for transverse cracks, which shall also be recorded asfailure.10. Report10.1 Report the following information:10.1.1 ASTM designation number of this test method,10.1.2 Batch identification number and total number ofparts in the batch,10.1.3 Number of parts tested,T
45、ABLE 1 Wedge Angle Selection (in degrees)Nominal Size ofThreaded ArticleArticles with UnthreadedLengths Less than2 DiametersArticles withUnthreaded Lengths 2Diametersand Longer2to6mm 6 6116 to14 in. 6 66to18mm 4 614 to34 in. 4 6over 18 to 38 mm 0 4over34 to 112 in. 0 4B83904310.1.4 Number of broken
46、parts, parts with visible cracks orother observed failures, and parts that exhibited relaxed torque,and10.1.5 Duration of the test method.11. Precision and Bias11.1 PrecisionThe precision of this test method has notbeen determined.11.2 BiasThe bias has not been determined.12. Keywords12.1 hydrogen e
47、mbrittlement test; metallic coated; residualembrittlement test; testing threaded articles; threaded fasteners;threaded rodAPPENDIX(Nonmandatory Information)X1. SOURCES OF INTRODUCTION OF HYDROGEN INTO THREADED ARTICLESX1.1 The preparation and metallic coating of threadedarticles, fasteners, and rod
48、are usually accomplished by thebarrel-plating process. In this process, quantities of an item areplaced within a containment vessel, called a barrel. The barrelis designed to move the group of items, together, through eachof the process steps, allowing ready ingress and egress ofprocessing solutions
49、 and rinses. As the barrel is moved throughthe process steps, it is also rotated such that the individualitems are constantly cascading over one another. In some of theprocess steps, notably the electrocleaning and electroplatingsteps, an electric current is applied to the group of items. Thecascading action randomly exposes the surfaces of eachindividual piece to the process electrodes while also maintain-ing electrical continuity among all the parts.X1.2 During both the electrolytic and non-electrolytic stepshydrogen is generated and exposed to the
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