ASTM A802 A802M-1995(2010) Standard Practice for Steel Castings Surface Acceptance Standards Visual Examination《钢铸件外观检查表面验收标准的标准实施规程》.pdf

1、Designation: A802/A802M 95 (Reapproved 2010)Standard Practice forSteel Castings, Surface Acceptance Standards, VisualExamination1This standard is issued under the fixed designation A802/A802M; the number immediately following the designation indicates the yearof original adoption or, in the case of

2、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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice c

3、overs 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 surface tex

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

5、ptions 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 the ap

6、plica-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 core st

7、resses 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 raised

8、, 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 blocks, t

9、hat 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 edges (

10、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 orcor

11、e 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 a sof

12、tmold, 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 low te

13、mperature,and are distinguished from the more severe phenomenon oflaps, folds, or cold shuts where the casting surface is actuallyfolded over.2.1.3.2 laps, folds, and cold shuts, ninterchangeableterms to describe the appearance of the casting surface that is1This practice is under the jurisdiction o

14、f ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.18 on Castings.Current edition approved Oct. 1, 2010. Published December 2010. Originallyapproved in 1982. Last previous edition approved in 2006 as A802/A802M 95 (2006). DOI: 10.1520

15、/A0802_A0802M-95R10.2Available from The Castings Development Centre, 7 East Bank Road,Sheffield, UK S2 3PT.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.actually folded over. They develop due to low temperature,unfavorable flow con

16、ditions caused by oxide films, 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

17、, malformed edges of more severe 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 solidifyi

18、ng metal orthe surrounding mold.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 castin

19、g surface.2.1.5.2 internal chills, 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 wi

20、th chaplets.2.1.6 linear discontinuities, 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 cr

21、acks are referred to ascold, 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 s

22、paces, or shortly after solidificationis 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 ce

23、roxides, slag, and sand are 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 displaceme

24、nt of molten metal. Ceroxides 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 appe

25、arance of the depression and 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 by

26、machining, na shrinkage void 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 h

27、ave a multi-directional lay, 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 s

28、patter, nweld metal droplets 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 (seeSe

29、ction 4),3.1.2 If any types 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

30、802/A 802M shall be a matter 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

31、D5Expansion discontinuities . . .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.A802/A802M 95 (2010)25. Keywords5.1 steel castings; surface acceptance standards; vi

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