1、Designation: A986/A986M 01 (Reapproved 2016)Standard Specification forMagnetic Particle Examination of Continuous Grain FlowCrankshaft Forgings1This standard is issued under the fixed designation A986/A986M; the number immediately following the designation indicates the yearof original adoption or,
2、in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the magnetic particle exami-nation of forged continuous
3、 grain flow (CGF) crankshaftsintended for medium speed diesel engines.1.2 For the purpose of magnetic particle indicationassessment, the crankshaft is divided into four zones ofdecreasing operational stress.Acceptance criteria have been setfor each zone.1.3 The engines to which these crankshafts are
4、 fitted arecommonly used for diesel electric locomotives, marinepropulsion, and power generation. Engines fueled by naturalgas also fall into this medium speed category.1.4 Specification A983/A983M is a product specificationthat covers the manufacture of CGF crankshafts.1.5 The values stated in eith
5、er inch-pound units or SI unitsare to be regarded separately as standard. Within the text, theSI units are shown in brackets. The values stated in eachsystem are not exact equivalents; therefore, each system shallbe used independently of the other. Combining values from thetwo systems may result in
6、nonconformance with the specifi-cation.2. Referenced Documents2.1 ASTM Standards:2A788/A788M Specification for Steel Forgings, General Re-quirementsA966/A966M Practice for Magnetic Particle Examination ofSteel Forgings Using Alternating CurrentA983/A983M Specification for Continuous Grain FlowForged
7、 Carbon and Alloy Steel Crankshafts for MediumSpeed Diesel Engines3. Ordering Information3.1 Specification A983/A983M requires that crankshaftsmade to that specification be examined in accordance withSpecification A986/A986M for magnetic particle examination.It is the responsibility of the purchaser
8、 to specify any changesto the zone allocations for the crankshaft surfaces.4. Procedure4.1 Magnetic particle examination shall be conducted inaccordance with Practice A966/A966M. The use of prod typecontacts is not permitted on finished crankshaft surfaces.Magnetic leeches may be used only on flat n
9、oncritical surfaces,and within the limitations specified in Practice A966/A966M.4.2 The magnetic particle examination shall be conductedusing the wet fluorescent method described in Practice A966/A966M.5. Areas of Examination5.1 Zone 1Major Critical Areas:5.1.1 Crankpin JournalsThe major critical ar
10、ea of eachcrankpin journal shall include that area 660 from the 6 oclockposition of the crankpin and extend38 in. 10 mm above thefillet collar and58 in. 15 mm along the crankpin surface asmeasured from the blend of the fillet radius and the journalsurface. These positions are shown in Fig. 1.5.1.2 M
11、ain Bearing JournalsThe major critical areas ofany main bearing journal shall include that area 660 from the12 oclock position on top of the journal and extend38 in.10 mm above the fillet collar and58 in. 15 mm along thejournal as measured from the blend of the fillet radius and thejournal surface.
12、These positions are shown in Fig. 1.5.1.3 Oil HolesThe major critical areas in also shallinclude the surfaces surrounding the journal oil holes. Thediameter of this critical area shall be 3d, where d is the oil holediameter before the radius. The critical area shall be centeredon the centerline of t
13、he oil hole. In addition, the Zone 1 criticalarea shall extend down the oil hole for a distance from thejournal surface equal to the hole diameter.5.2 Zone 2Minor Critical Areas:5.2.1 The Zone 2 minor critical areas shall include thebalance of the fillet radii of the crankpin and main bearingjournal
14、s not included in the major critical areas.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.06 on Steel Forgings and Billets.Current edition approved Sept. 1, 2016. Published September
15、2016. Originallyapproved in 1998. Last previous edition approved in 2011 as A986/A986M 01(2011). DOI: 10.1520/A0986_A0986M-01R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informati
16、on, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2.2 When counterweights are attached to the crankshaftwebs by welding, the weld surfaces and12 in. 13 mm of theadjac
17、ent surfaces shall be considered minor critical areas.5.3 Zone 3Journal Running Surfaces:5.3.1 Zone 3 includes the remainder of the crankpin andmain bearing journal surfaces not covered by the major andminor critical areas.5.3.2 Zone 3 also includes the bearing journal surfaces forauxiliary drives,
18、gear fit surfaces, keyways, and couplingflange radii.5.4 Zone 4All Other Areas:5.4.1 Zone 4 includes the crankpin web surfaces, excludingareas covered by the major and minor critical areas, flangefaces and periphery, and any other surfaces not included inZones 1, 2, or 3.6. Classification of Indicat
19、ions6.1 Surface magnetic particle indications shall be classifiedas open or non-open.6.1.1 Open indications are defined as those being visibleafter removal of the magnetic particles under a minimum 5times optical magnification.6.1.2 Non-open indications are not visible after removal ofthe magnetic p
20、articles.7. Acceptance Criteria7.1 Zone 1:7.1.1 Indications are not permitted and must be removed bygrinding or polishing. The original shape of the fillet must bemaintained, when indications have been removed. The blendedarea shall not be deeper than 0.006 in. 0.15 mm below theminimum drawing fille
21、t dimension for the location.7.1.2 The total area blended at less than the relevantminimum dimension shall not exceed 5 % of the major criticalarea of the particular crankpin or main bearing fillet ordesignated surface at an oil hole.7.2 Zone 2:7.2.1 Open indications are not permitted and must berem
22、oved. The depth of the resulting depression shall notexceed 0.010 in. 0.25 mm below the minimum fillet dimen-sion for the location. The total area of depressions or dimplesin a Zone 2 fillet shall not exceed 5 % of the Zone 2 fillet area.7.2.2 Non-open indications are permitted up to a maximumlength
23、 of 2 % of D, where D is the diameter of the journal inquestion. The maximum total length of non-open indications ina Zone 2 fillet location shall not exceed 0.75 in. 20.0 mm, andthe individual indications must be separated from each other bya minimum length of 2 % of D.7.2.3 Non-open indications ex
24、ceeding the length limitationsof 7.2.2, either individually or in total, may be dimpled to amaximum depth of 0.010 in. 0.25 mm below the minimumdrawing dimension, but the aggregate length and area limita-tions of 7.2.1 and 7.2.2 shall apply.7.2.4 The combined dimple areas in any main or crankpinjour
25、nal fillet shall not exceed 8 % of the total fillet area.7.2.5 For welds attaching counterweights to crankshaftwebs, the following acceptance criteria apply.7.2.5.1 The surfaces to be examined shall be prepared togive a surface finish of at least 250 in. 6.35 m.FIG. 1A986/A986M 01 (2016)27.2.5.2 Lin
26、ear indications shall not exceed132 in. 1 mm inlength in the weld areas of the counterweight sides (posts).Indications exceeding this size shall be ground to a maximumdepth of18 in. 3 mm below the minimum weld dimensionand re-examined. If the indication has been removed, orreduced to an acceptable l
27、ength, the resulting dimple shall beblended to transition smoothly with the surrounding surface. Ifthe indication is still unacceptable in length, it shall beremoved completely and the area restored by welding inaccordance with the qualified welding procedure.7.2.5.3 The end faces and corners of the
28、 counterweightwelds, and 1 in. 25 mm along each side extending from thecorners shall exhibit no indications. Any indications shall beremoved by grinding, and the resulting dimple shall not exceed316 in. 5 mm in depth below the minimum weld dimension,and12 in. 13 mm in length. If the dimple extends b
29、eyondthese dimensions, the area shall be repair welded in accordancewith the qualified procedure. If more than14 in. 6 mm ofstock is removed from any weld corner, the area shall berestored by repair welding, again in accordance with thequalified procedure.7.3 Zone 3:7.3.1 Open indications not exceed
30、ing 0.20 in. 5.0 mm inlength individually in any one Zone 3 location, provided thatthe total length does not exceed 0.50 in. 13.0 mm in any 1 in.2650 mm2 of surface area.7.3.2 Open indications in excess of 0.20 in. 5.0 mm inlength may be removed by dimpling to a maximum depth of0.010 in. 0.25 mm bel
31、ow the minimum drawing dimensionfor the location. The area of the resulting dimples shall notexceed 3 % of the Zone 3 location area.7.3.3 Non-open indications exceeding 0.20 in. 5.0 mm inlength are considered to be relevant. Relevant indicationsexceeding the greater of 0.5 in. 13.0 mm or 6 % of D, w
32、hereD is the diameter of the journal in question, are unacceptable,but may be reduced to an acceptable length by dimpling to adepth not to exceed 0.010 in. 0.25 mm. The total length ofrelevant non-open indications in any one Zone 3 location shallnot exceed 2.0 in. 50 mm.7.4 Zone 4:7.4.1 Open indicat
33、ions exceeding 0.25 in. 6.0 mm areconsidered to be relevant, and the total length of such indica-tions in any one Zone 4 location shall not exceed 1.0 in.25 mm. Open indications, regardless of length, separated byless than18 in. 3 mm shall be considered to be a singleindication.7.4.2 Dimpling of rel
34、evant open indications may be done tomeet the requirements of 7.4.1 up to a maximum depth of0.25 in. 5.0 mm.7.4.3 Non-open indications not exceeding 1.0 in. 25.0 mmin length are acceptable, provided that the total length ofindications exceeding 0.25 in. 6.0 mm does not exceed 4.0 in.100.0 mm in any
35、25 in.216 000 mm2 area.7.4.4 Dimpling of non-open indications to a maximumdepth of 0.40 in. 10.0 mm in a particular Zone 4 location maybe done to bring the length limitation requirements intocompliance with 7.4.3.8. Dimpling8.1 To dimple means to stone or grind to remove stock in anarea that contain
36、s an unacceptable indication. In order tominimize stress concentrations, all dimples shall have a bottomradius of approximately three times the dimple depth, and shallbe smoothly blended to the surface area. The finish in thedimple shall be at least equal to that of the adjacent surface.8.2 When mak
37、ing a dimple in a surface to remove a visualor magnetic particle indication, care must be taken to avoid theunnecessary reduction in bearing surface on a bearing journal.When a crankshaft has been surface hardened by nitriding orinduction hardening, caution must be exercised to avoidexcessive penetr
38、ation into the case, particularly in the criticalareas.9. Inspection9.1 The requirements of Specification A788/A788M shallapply.10. Rejection10.1 The requirements of Specification A788/A788M shallapply.11. Certification11.1 The requirements of Specification A788/A788M shallapply.ASTM International t
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42、the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 01 (2016)3
