ASTM A802-1995(2015) Standard Practice for Steel Castings Surface Acceptance Standards Visual Examination《钢铸件 表面验收标准和视觉检测的标准实施规程》.pdf

1、Designation: A802 95 (Reapproved 2015)Standard Practice forSteel Castings, Surface Acceptance Standards, VisualExamination1This standard is issued under the fixed designation A802; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th

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

3、he 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 texture, s

4、urfaceroughness, and surface discontinuities described as follows:Acceptance levelsASurface TextureBNonmetallic InclusionsCGas PorosityDSolidification DiscontinuitiesESand Expansion DiscontinuitiesFMetal InsertsGThermally Cut SurfacesHMechanically Prepared SurfacesJWelded Surfaces1.3 Descriptions of

5、 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 applica-bil

6、ity 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 stresses du

7、ring 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, rough a

8、rea 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, that are i

9、ncorporated 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 (raised ar

10、eas 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 orcore and mol

11、d. 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 softmold, or

12、 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 temperature

13、,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 Alloysand is the direct responsibility of SubcommitteeA01.18 on Cas

14、tings.Current edition approved Nov. 1, 2015. Published November 2015. Originallyapproved in 1982. Last previous edition approved in 2010 as A802/A802M 95 (2010)2. DOI: 10.1520/A0802-95R15.2Available from Castings Technology International, Advanced ManufacturingPark, Brunel Way, Rotherham, S60 5WG, S

15、outh Yorkshire, England. http:/.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.1.3.2 laps, folds, and cold shuts, ninterchangeableterms to describe the appearance of the casting surface that isactually folded over. They develop due

16、 to low temperature,unfavorable flow conditions 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 edge

17、s, for a mild degree of misrun.Irregular, 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 evo

18、lution of gas, either from the solidifying 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 ca

19、use irregular contactareas on the casting 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 si

20、milar to those that may be associated with chaplets.2.1.6 linear discontinuities, nelongated discontinuitiesare considered linear if their length equals or exceeds threetimes the width.2.1.6.1 cracks, n cold and hot, less jagged, sometimesstraight ruptures that occur after solidification of the cast

21、ing,due to excessive strain. Sometimes cracks 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

22、 still someliquid in the interdendritic spaces, 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 inclusio

23、ns, ncasting surface inclusionssuch as ceroxides, 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 o

24、n the surface of thecasting by displacement 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 cer

25、oxides. They differ by a morerounded appearance 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 shrinkag

26、e under risers and gates, and revealed bymachining, 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

27、.2.1.10 surface texture, ncast surfaces have 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 cont

28、rol of welding operations.2.1.11.2 weld spatter, 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 diff

29、erent surfaces of the same casting (seeSection 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.TABLE 1 Visu

30、al 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 . . .A.AE3 E5Inserts . . .A.AF1 F3Metal removal marks:Thermal G1 G2

31、G3 G5Mechanical H1 H3 H4 H5Welds J1J2J3J5ANo reference comparator plate is available for this surface feature and level.A802 95 (2015)24.2 Surface discontinuities not covered in Practice A802/A802M shall be a matter of agreement between the purchaserand the manufacturer.5. Keywords5.1 steel castings

32、; surface acceptance standards; visualASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the r

33、iskof infringement of such rights, are entirely their own responsibility.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 t

34、his standard or for additional standardsand should be addressed 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 shouldmak

35、e your views known to the ASTM Committee on Standards, at 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 b

36、y 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:/ 95 (2015)3