rtDesignation:A 802/A 802M –95(Reapproved 2001)
Standard Practice for
possible是什么意思Steel Castings,Surface Acceptance Standards,Visual Examination 1
This standard is issued under the fixed designation A 802/A 802M;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.
A number in parenthes 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 u by agencies of the Department of Defen.
1.Scope
1.1This practice covers the acceptance criteria for the surface inspection of steel castings by visual examination.Four levels of acceptance standards are provided.
1.2Acceptance levels utilize Steel Castings Rearch and Trade Association (SCRATA)2graded reference comparators for the visual determination of surface texture,surface rough-ness,and surface discontinuities described as follows:
Acceptance levels
A—Surface Texture
B—Nonmetallic Inclusions C—Gas Porosity
D—Solidification Discontinuities E—Sand Expansion Discontinuities F—Metal Inrts
G—Thermally Cut Surfaces
H—Mechanically Prepared Surfaces J—Welded Surfaces
1.3Descriptions of terms related to casting discontinuities are in Section
2.
1.4This standard does not purport to address all of the safety concerns,if any,associated with its u.It is the responsibility of the ur of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to u.
太空陨石2.Terminology
2.1Definitions of Terms Specific to This Standard:2.1.1expansion discontinuities:
2.1.1.1veins,n —raid,narrow,linear ridges that form upon cracking of the sand mold or core due to expansion of sand and the resulting mold or core stress during filling of the mold with liquid steel.
2.1.1.2rat tails,n —long,narrow,linear depressions or small steps occurring on a casting surface.Rat t
ails form as a result of sand expansion and minor buckling of the mold surface during filling of the mold with liquid metal.
2.1.1.3scab,n —a raid,rough area on a casting that usually consists of a crust of metal covering a layer of sand.Sometimes,a scab consists of a raid,rough area of esn-tially solid metal on the surface of a casting.2.1.2external chills:
2.1.2.1external chills,n —usually metal blocks,or graphite and carbon blocks,that are incorporated into the mold to locally increa the rate of heat removal during solidification.Brackets have the same purpo but reprent an integral part of the casting.Brackets are produced by providing suitable cavities in the mold or core.External chills may produce flat spots and edges (raid areas or depressions)on the casting surface.Brackets merely change the casting appearance due to their prence.Brackets may be removed or allowed to remain on the casting.
2.1.2.2parting line and core print fins,n —thin projections of excess metal at the parting plane between mold halves or core and mold.Caus are improper closing of the mold,insufficient weighting or clamping of the mold for pouring,or uneven pattern surfaces at the matching locations.Core print fins are usually caud by improper dimensions of core prints of the pattern or c
ore box,by rough placement of cores in a soft mold,or by inadequately cured cores.2.1.3fusion discontinuities:cherokee
2.1.
you3.1wrinkles,n —elongated,smooth depressions of the casting surface,frequently appearing in cloly spaced groups.Wrinkles result from irregularities of the liquid metal flow in the mold cavity,frequently associated with low temperature,and are distinguished from the more vere phenomenon of laps,folds,or cold shuts where the casting surface is actually folded over.
2.1.pip
3.2laps,folds,and cold shuts,n —interchangeable terms to describe the appearance of the casting surface that is actually folded over.They develop due to low temperature,unfavorable flow conditions caud by oxide films,or combi-nations thereof.
1
This practice is under the jurisdiction of ASTM Committee A01on Steel,Stainless Steel,and Related Alloysand is the direct responsibility of Subcommittee A01.18on Castings.
Current edition approved Sept.10,1995.Published November 1995.Originally published as A 802–82.Last previous edition A 802/A 802M –89.2
Available from The Castings Development Centre,7East Bank Road,Sheffield,UK S23PT.
1
Copyright ©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United
States.
2.1.
3.3misrun,n—an incompletely formed casting,due to only partialfilling of the mold cavity when the liquid metal solidifies prematurely.The resulting casting appearance is characterized by rounded edges,for a mild degree of misrun. Irregular,malformed edges of more vere misruns,and not fully formed castings,are characteristic.Frequently,misruns are associated with such discontinuities as wrinkles or laps and folds,or both.
2.1.4gas porosity,n—a concave discontinuity in castings due to the evolution of gas,either from the solidifying metal or the surrounding mold.
2.1.5inrts:
2.1.5.1chaplets,n—metallic(steel)devices ud to main-tain the spacing between the core and the mold.Low liquid metal temperature and unfavorableflow conditions in the mold may produce insufficient fusion and cau irregular contact areas on the casting surface.
2.1.5.2internal chills,n—metallic(steel)devices ud to locally increa the rate of heat removal during solidification. Incomplete fusion due to low liquid steel temperatures and prevailingflow conditions may produce irregularities of the surface similar to tho that may be associated with chaplets.
2.1.6linear discontinuities,n—elongated discontinuities are considered linear if their length equals or exceeds three times the width.
2.1.6.1cracks,n—cold and hot,less jagged,sometimes straight ruptures that occur after solidification of the casting, due to excessive strain.Sometimes cracks are referred to as cold,hot,or heat treat-cracks to indicate the condition of the castings,or the operation during which the cracks occur.
2.1.6.2hot tears,n—jagged ruptures in castings that occur during thefinal stages of solidification,while there is still some liquid in the interdendritic spaces,or shortly after solidification is complete.
fault是什么意思2.1.7metal removal marks,n—flame cutting and air carbon-arc cutting produce parallel grooves in the cut-off area.Finer marks are produced with the abrasive cut-off wheel and grinding.
2.1.8nonmetallic inclusions,n—casting surface inclusions such as ceroxides,slag,and sand are partially or completely removed during the cleaning process of pressure blasting. Surface discontinuities left by the inclusions are referred to by the inclusion type that caud their formation:
2.1.8.1Ceroxides cau depressions on the surface of the casting by displacement of molten metal.Ceroxides consist of a mixture of low-melting oxides and partially fud sand.The crater-like appearance of the casting surface depression is typical.
肤浅的英文
2.1.8.2Depressions on the casting surface caud by slag are similar to tho caud by ceroxides.They differ by a more rounded appearance of the depression and do not exhibit the crater-like appearance of ceroxides.
2.1.8.3Depressions caud by sand are similar to tho of ceroxides and slag.Their appearance may,at times,more cloly reflect the granular nature of the sand.
2.1.9shrinkage under rirs and gates,and revealed by machining,n—a shrinkage void is a discontinuity in castings due to the lack of available liquid feed metal during solidifi-cation contraction.Rir removal and machining may reveal shrinkage that extends from the interior of the casting to the near surface area.
2.1.10surface texture,n—cast surfaces have a multi-directional lay,without the uniform quence of ridges and valleys of machined surfaces.
2.1.11welding:清清语言培训机构创始人>卧槽族
2.1.11.1weld undercuts,n—narrow elongated depressions that border the weld contour and result from improper welding conditions or inadequate control of welding operations.
2.1.11.2weld spatter,n—weld metal droplets that solidified against and adhere to the component being welded.
3.Ordering Information
3.1The inquiry and order should specify the following information:
3.1.1Acceptance Level—More than one acceptance level may be specified for different surfaces of the same casting(e Section4),
3.1.2If any types of discontinuities are unacceptable,
3.1.3Extent of casting surfaces to be examined,and
3.1.4Number of castings to be examined.
4.Acceptance Standards
4.1Levels of acceptance for visual inspection are listed in Table1.
4.2Surface discontinuities not covered in Practice A802/ A802M shall be a matter of agreement between the purchar and the manufacturer.
5.Keywords
5.1steel castings;surface acceptance standards;
visual
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TABLE 1Visual Inspection Acceptance Criteria
Surface Feature Level I Level II Level III Level IV Surface texture
A1A2A3A4Nonmetallic inclusions B1B2B4B5Gas porosity
C2C1C3C4Fusion discontinuities ...A D1D2D5Expansion discontinuities ...A ...A E3E5Inrts
...A ...A F1F3Metal removal marks:Thermal G1G2G3G5Mechanical H1H3H4H5Welds
J1
J2
J3
J5
A
No reference
comparator plate is available for this surface feature and level.
