ASTM A802 A802M-1995(2006) Standard Practice for Steel Castings Surface Acceptance Standards Visual Examination《钢铸件肉眼检查表面验收标准的标准规程》.pdf

1、Designation: A 802/A 802M 95 (Reapproved 2006)Standard Practice forSteel Castings, Surface Acceptance Standards, VisualExamination1This standard is issued under the fixed designation A 802/A 802M; the number immediately following the designation indicates the yearof original adoption or, in the case

2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This pract

3、ice covers the acceptance criteria for thesurface inspection of steel castings by visual examination. Fourlevels of acceptance standards are provided.1.2 Acceptance levels utilize Steel Castings Research andTrade Association (SCRATA)2graded reference comparatorsfor the visual determination of surfac

4、e texture, surface rough-ness, and surface discontinuities described as follows:Acceptance levelsASurface TextureBNonmetallic InclusionsCGas PorosityDSolidification DiscontinuitiesESand Expansion DiscontinuitiesFMetal InsertsGThermally Cut SurfacesHMechanically Prepared SurfacesJWelded Surfaces1.3 D

5、escriptions of terms related to casting discontinuitiesare in Section 2.1.4 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 appro-priate safety and health practices and determine t

6、he applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 expansion discontinuities:2.1.1.1 veins, nraised, narrow, linear ridges that formupon cracking of the sand mold or core due to expansion ofsand and the resulting mold or co

7、re stresses during filling of themold with liquid steel.2.1.1.2 rat tails, nlong, narrow, linear depressions orsmall steps occurring on a casting surface. Rat tails form as aresult of sand expansion and minor buckling of the moldsurface during filling of the mold with liquid metal.2.1.1.3 scab, na r

8、aised, rough area on a casting thatusually consists of a crust of metal covering a layer of sand.Sometimes, a scab consists of a raised, rough area of essen-tially solid metal on the surface of a casting.2.1.2 external chills:2.1.2.1 external chills, nusually metal blocks, or graphiteand carbon bloc

9、ks, that are incorporated into the mold tolocally increase the rate of heat removal during solidification.Brackets have the same purpose but represent an integral partof the casting. Brackets are produced by providing suitablecavities in the mold or core. External chills may produce flatspots and ed

10、ges (raised areas or depressions) on the castingsurface. Brackets merely change the casting appearance due totheir presence. Brackets may be removed or allowed to remainon the casting.2.1.2.2 parting line and core print fins, nthin projectionsof excess metal at the parting plane between mold halves

11、orcore and mold. Causes are improper closing of the mold,insufficient weighting or clamping of the mold for pouring, oruneven pattern surfaces at the matching locations. Core printfins are usually caused by improper dimensions of core printsof the pattern or core box, by rough placement of cores in

12、a softmold, or by inadequately secured cores.2.1.3 fusion discontinuities:2.1.3.1 wrinkles, nelongated, smooth depressions of thecasting surface, frequently appearing in closely spaced groups.Wrinkles result from irregularities of the liquid metal flow inthe mold cavity, frequently associated with l

13、ow temperature,and are distinguished from the more severe phenomenon oflaps, folds, or cold shuts where the casting surface is actuallyfolded over.1This practice is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel, and Related Alloys and is the direct responsibility of Subcommit

14、teeA01.18 on Castings.Current edition approved March 1, 2006. Published April 2006. Originallyapproved in 1982. Last previous edition approved in 2001 as A 802/A 802M 95(2001).2Available from The Castings Development Centre, 7 East Bank Road,Sheffield, UK S2 3PT.1Copyright ASTM International, 100 Ba

15、rr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.1.3.2 laps, folds, and cold shuts, ninterchangeableterms to describe the appearance of the casting surface that isactually folded over. They develop due to low temperature,unfavorable flow conditions caused by oxide film

16、s, or combi-nations thereof.2.1.3.3 misrun, nan incompletely formed casting, due toonly partial filling of the mold cavity when the liquid metalsolidifies prematurely. The resulting casting appearance ischaracterized by rounded edges, for a mild degree of misrun.Irregular, malformed edges of more se

17、vere misruns, and notfully formed castings, are characteristic. Frequently, misrunsare associated with such discontinuities as wrinkles or laps andfolds, or both.2.1.4 gas porosity, na concave discontinuity in castingsdue to the evolution of gas, either from the solidifying metal orthe surrounding m

18、old.2.1.5 inserts:2.1.5.1 chaplets, nmetallic (steel) devices used to main-tain the spacing between the core and the mold. Low liquidmetal temperature and unfavorable flow conditions in the moldmay produce insufficient fusion and cause irregular contactareas on the casting surface.2.1.5.2 internal c

19、hills, nmetallic (steel) devices used tolocally increase the rate of heat removal during solidification.Incomplete fusion due to low liquid steel temperatures andprevailing flow conditions may produce irregularities of thesurface similar to those that may be associated with chaplets.2.1.6 linear dis

20、continuities, nelongated discontinuitiesare considered linear if their length equals or exceeds threetimes the width.2.1.6.1 cracks, ncold and hot, less jagged, sometimesstraight ruptures that occur after solidification of the casting,due to excessive strain. Sometimes cracks are referred to ascold,

21、 hot, or heat treat-cracks to indicate the condition of thecastings, or the operation during which the cracks occur.2.1.6.2 hot tears, njagged ruptures in castings that occurduring the final stages of solidification, while there is still someliquid in the interdendritic spaces, or shortly after soli

22、dificationis complete.2.1.7 metal removal marks, nflame cutting and air carbon-arc cutting produce parallel grooves in the cut-off area. Finermarks are produced with the abrasive cut-off wheel andgrinding.2.1.8 nonmetallic inclusions, ncasting surface inclusionssuch as ceroxides, slag, and sand are

23、partially or completelyremoved during the cleaning process of pressure blasting.Surface discontinuities left by these inclusions are referred toby the inclusion type that caused their formation:2.1.8.1 Ceroxides cause depressions on the surface of thecasting by displacement of molten metal. Ceroxide

24、s consist ofa mixture of low-melting oxides and partially fused sand. Thecrater-like appearance of the casting surface depression istypical.2.1.8.2 Depressions on the casting surface caused by slagare similar to those caused by ceroxides. They differ by a morerounded appearance of the depression and

25、 do not exhibit thecrater-like appearance of ceroxides.2.1.8.3 Depressions caused by sand are similar to those ofceroxides and slag. Their appearance may, at times, moreclosely reflect the granular nature of the sand.2.1.9 shrinkage under risers and gates, and revealed bymachining, na shrinkage void

26、 is a discontinuity in castingsdue to the lack of available liquid feed metal during solidifi-cation contraction. Riser removal and machining may revealshrinkage that extends from the interior of the casting to thenear surface area.2.1.10 surface texture, ncast surfaces have a multi-directional lay,

27、 without the uniform sequence of ridges andvalleys of machined surfaces.2.1.11 welding:2.1.11.1 weld undercuts, nnarrow elongated depressionsthat border the weld contour and result from improper weldingconditions or inadequate control of welding operations.2.1.11.2 weld spatter, nweld metal droplets

28、 that solidifiedagainst and adhere to the component being welded.3. Ordering Information3.1 The inquiry and order should specify the followinginformation:3.1.1 Acceptance LevelMore than one acceptance levelmay be specified for different surfaces of the same casting (seeSection 4),3.1.2 If any types

29、of discontinuities are unacceptable,3.1.3 Extent of casting surfaces to be examined, and3.1.4 Number of castings to be examined.4. Acceptance Standards4.1 Levels of acceptance for visual inspection are listed inTable 1.4.2 Surface discontinuities not covered in Practice A 802/A 802M shall be a matte

30、r of agreement between the purchaserand the manufacturer.TABLE 1 Visual Inspection Acceptance CriteriaSurface Feature Level I Level II Level III Level IVSurface texture A1 A2 A3 A4Nonmetallic inclusions B1 B2 B4 B5Gas porosity C2 C1 C3 C4Fusion discontinuities . . .AD1 D2 D5Expansion discontinuities

31、 . . .A.AE3 E5Inserts . . .A.AF1 F3Metal removal marks:Thermal G1 G2 G3 G5Mechanical H1 H3 H4 H5Welds J1J2J3J5ANo reference comparator plate is available for this surface feature and level.A 802/A 802M 95 (2006)25. Keywords5.1 steel castings; surface acceptance standards; visualASTM International ta

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33、esponsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addre

34、ssed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at t

35、he 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).A 802/A 802M 95 (2006)3