Designation:E381–01(Reapproved2006)
Standard Method of
Macroetch Testing Steel Bars,Billets,Blooms,and
Forgings1
This standard is issued under thefixed designation E381;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(´)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
1.1Macroetching,which is the etching of specimens for macrostructural examination at low magnifications,is a fre-quently ud technique for evaluating steel products such as bars,billets,blooms,and forgings.
1.2Included in this method is a procedure for rating steel specimens by a graded ries of photographs showing the incidence of certain conditions.The method is limited in application to bars,billets,blooms,and forgings of carbon and low alloy steels.
1.3A number of different etching reagents may be ud depending upon the type of examination to be made.Steels react differently to etching reagents becau of variations in chemical composition,method of manufacture,heat treatment and many other variables.Establishment of general standards for acceptance or rejection for all conditions is impractical as some conditions must be considered relative to the part in which it occurs.
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.See the specific precautionary statement in5.3.
2.Referenced Documents
2.1ASTM Standards:2
E7Terminology Relating to Metallography
E340Test Method for Macroetching Metals and Alloys
E1180Practice for Preparing Sulfur Prints for Macrostruc-tural Evaluation
2.2ASTM Adjuncts:
Photographs for Rating Macroetched Steel(3plates)3
3.Terminology
3.1Definitions—For definitions of terms ud in this method,e Terminology E7.
3.2Definitions of Terms Specific to This Standard:
3.2.1Terminology Applicable Only to Ingot Cast Product: 3.2.1.1splash—a nonuniform etch pattern where irregularly-shaped areas exhibit a different etch contrast than surrounding areas.Splash is normally associated with molten steel which solidifies and oxidizes during initial pouring and which is not completely redissolved by the remaining molten steel.
3.2.1.2butt tears—subsurface cracks normally parallel to the surface of the ingot mold wall.
odbc3.2.1.3flute cracks—cracks perpendicular to the surface of the ingot mold wall which may,or may not,extend to the surface of the product.
3.2.1.4burst—a single or multi-rayed crack normally lo-cated at the center of the wrought product.
3.2.2Definitions Applicable Only to Continuously Cast Products:
3.2.2.1chill zone—rapidly cooled metal with afine struc-ture at the surface of the product which is normally continuous around that surface.
复活节是什么意思
3.2.2.2chill zone crack—any crack which is located par-tially or completely in the chill zone and may extend to the surface of the product.
3.2.2.3diagonal crack—a crack which lies completely or partially in the diagonal regions of a non-round product where adjacent columnar or dendritic growth patterns interct.
3.2.2.4subsurface crack—a crack perpendicular to and just beneath the chill zone.
3.2.2.5mid-radius crack—a crack perpendicular to the surface of the product located approximately halfway between the surface and center of the product.
3.2.2.6center crack—a crack with an aspect ratio(length/ width)of approximately3or greater located at,or near,the center of the product.
boton1This method is under the jurisdiction of ASTM Committee E04on Metallog-raphy,and is the direct responsibility of Subcommittee E04.01on Specimen Preparation.
Current edition approved Oct.1,2005.Published October2006.Originally approved in1968.Last previous edition approved in2001as E381–01.DOI: 10.1520/E0381-01R06.
2For referenced ASTM standards,visit the ASTM website,www.astm,or contact ASTM Customer Service at rvice@astm.For Annual Book of ASTM
Standards volume information,refer to the standard’s Document Summary page on the ASTM website.
3Available from ASTM Headquarters.Order Adjunct:ADJE038101(Plate I), ADJE038102(Plate II),and ADJE038103(Plate III).
Copyright©ASTM International,100Barr Harbou r Drive P.O.Box C700West Conshohocken,Pennsylvania19428-2959,United States
3.2.2.7star crack—a star-shaped or multi-rayed crack at the center of the product.
3.2.2.8scattered porosity—multiple round or irregularly-shaped pores uniformly distributed about the central portion of the product.
3.2.2.9white band—a light etching continuous band(s) parallel to the surface of the product usually located between the one-quarter and three-quarter radius position,normally associated with electromagnetic stirring.
3.2.2.10columnar grains—a coar structure of parallel, elongated grains formed by unidirectional growth during solidification.
3.2.3Conditions Applicable to Both Ingot and Continuously Cast Product:
3.2.3.1nonmetallic inclusions—nonmetallic particles trapped in the steel or the voids resulting when inclusions are dissolved by the macroetchant.
3.2.3.2pattern—a dark etching band,usually rectangular or square,enclosing the central portion of the cross ction, normally visible only in wrought product.In ingot cast product, it is sometimes called ingotism or ingot pattern.
3.2.3.3pipe or center void—a single large cavity located at, or near,the center of the product.
3.2.3.4center unsoundness—multiple round or irregularly-shaped voids concentrated at the center of the product.
3.2.3.5dark center—a dark etching area at the center of the product.Dark center is solid material and should not be confud with center unsoundness.
3.2.3.6pinholes—small pores which lie at,or just beneath, the surface of the product.
3.2.3.7mold slag—inclusions which are normally associ-ated with entrapped fud mold powder and
are normally located at,or just beneath,the surface of the product.They are usually found in continuously cast or bottom poured products.
3.2.3.8flakes—short discontinuous internal cracks attrib-uted to stress produced by localized transformation and hydrogen solubility effects during cooling after hot working.In an etched transver ction,they appear as short,tight discontinuities which are usually located in the midway to center location of the ction.They are also known as shatter cracks or hairline cracks.
3.2.3.9gassy—irregularly-shaped voids which may,or may not,be uniformly distributed throughout the cross ction. The may be located anywhere from the near surface region of the product to the center of the product,depending on the source and verity of the condition.
3.2.3.10dendritic—a“tree-like”pattern with branches(pri-mary,condary,and tertiary arms)due to compositional differences that ari during solidification.For a specific composition,a weak dendritic structure is associated with a low superheat while a strong dendritic structure is associated with a high superheat during casting.Compositional differ-ences also influence the clarity of the dendrites.
3.2.3.11refilled crack—A defect formed during the solidi-fication of continuously cast steel,either external(bulging)or internal(shrinkage)forces result in the paration of crystal-lites so as to permit s
olute rich liquid to refill the gap as it forms.
4.Significance and U
4.1Macroetching is ud in the steel industry becau it is
a simple test that will provide information about the relative homogeneity of the sample.The method employs the action of an acid or other corrosive agent to develop the macrostructural characteristics of a suitably prepared specimen.The name implies that the etched surface is examined visually,or at low magnifications(usually<103).
4.2Macroetching will show:(1)variations in structure such as grain size,dendrites,and columnar structure;(2)variations in chemical composition such as gregation,coring,and banding;and,(3)the prence of discontinuities such as laps, ams,cracks,porosity,bursts,pipe.andflakes.
4.3When,in accordance with the requirements of the inquiry,contract,order or specifications,forgings,billets, blooms,etc.,are to be produced subject to macroetch testing and inspection,the manufacturer and the purchar should be in agreement concerning the following:(1)the stage of manufacture at which the test shall be conducted;(2)the number and locations of the ctions to be examined;(3)the necessary surface preparation prior to etching of the specimen;
(4)the etching reagent,temperature,and time of etching;and,
(5)the type,size,number,location,and orientation of condi-tions that are to be considered injurious.
4.4When not specified,the procedures of the test may be lected by the manufacturer to satisfy the requirements of the governing specification.
4.5When agreed upon by purchar and producer,sulfur printing of as cast-ctions,if continuously cast,is an accept-able alternative to macroetching.Sulfur printing shall be performed in accordance with Practice E1180.Examination and rating of specimens shall be in accordance with Sections 10and11of this(E381)standard.
4.6Steel from ingots shall be examined according to pro-cedures described in Section9.Continuously cast steel blooms and billets,in the as cast condition,shall be examined according to the procedures described in Sections10and11. With reductions over a3:1area ratio,wrought product from continuously cast steel may be examined according to Section 9.
5.Reagents
5.1The most common reagent for macroetching iron and steel is a1:1mixture,by volume,of concentra
ted hydrochloric acid(HCl)and water.The hydrochloric acid need not be reagent grade.Commercial quality hydrochloric acid(also known as muriatic acid)is satisfactory.The etching solution should be clear and free from scum.It should be hot,70to 80°C(160to180°F).The reagent should be ud under a fume hood,or some other means of carrying off the corrosive fumes must be provided.The solution may be heated without rious change in concentration.The etching solution may be reud if it has not become excessively contaminated or weakened.
N OTE1—The addition of hydrogen peroxide(H
2
O
2
)may be necessary in order to provide sufficient reaction to properly etch some types of product.This should be added to an etching bath that is operating at room
temperature.
5.2A cond macroetching solution,favored by some as producing a clearer structure,is compod of concentrated HCl (38volume%),sulfuric acid,H2SO4(12volume%)and water, H2O(50volume%).(See5.1with respect to acid quality, heating,and ventilation.)
5.3Obrve caution in mixing macroetch solutions.The acids are strong and they can cau rious chemical burns. Add acid slowly to water with stirring.This is especially true for sulfuric acid.Mix solutions and macroetch under a fume hood.
5.4An ammonium persulfate solution,a10to20%aque-ous solution,is ud primarily on longitudinal ctions to detect certain types of ghost lines,gregation,flow lines,etc.
A freshly made solution is necessary for best results.The solution should be swabbed on thefinished surface at room temperature.Inspection is most effective when done while the piece is still wet.
5.5A nitric acid solution,5%or10%nitric acid in alcohol or water,is ud to detect local overstraining,grinding cracks, overheated areas,and depth of carburized or decarburized surface zones.The u of this reagent necessitates a smooth surface.The reagent is ud at room temperature by immersion or swabbing.
5.6Many other reagents have been ud for special appli-cations.When the u of a reagent other than tho described in5.2-5.5is desired,it should be by agreement between the purchar and the manufacturer.(See Test Method E340for other etching solutions.)
6.Sampling
6.1When macroetching is ud as an inspection procedure, sampling should be done at an early stage of manufacture so that,if the material is inadequate,the minimum amount of unnecessary processing is done(or the processing can be modified to salvage the material).For ingot cast product,the specimen is usually taken after ingot breakdown.Billets or blooms going into small sizes are sampled after the initial breakdown.Sampling of continuously cast product is usually done in the as-cast condition,or after intermediate orfinal processing,depending on size and preference.Random sam-pling of thefinished product may be performed if the locations within the cast are not known.lrp
6.2Normally,the specimens are disks cut from the ends of bars,billets or blooms.Enough material should be discarded before taking the specimen to eliminate any extraneous effects of rolling such as“fish tails.”Specimens may be cut cold by any convenient means;saws and abrasive cut-off wheels are particularly effective.Torch cutting or other hot cutting will materially affect the structure of the spe
cimen and may be ud only when necessary to remove a larger piece prior to cutting to size by cold methods.Sufficient torch cut material should be removed by cold cutting to eliminate the thermal effects of torch cutting.
6.3The macroetch test,as applied to the inspection of steel products of this specification,is carried out on slices,usually 13to25mm(1⁄2to1in.)in thickness.Disks or specimens are usually cut to reveal a transver surface,but the requirements of the specification,contract,or order may include the prepa-ration and examination of a longitudinal surface.
6.4When the test is conducted on single pieces(bar,billet, bloom,etc.),the purchar may specify that the specimen disks be cut to reprent both ends,or only one end,of the piece.
6.5When the test is conducted on a number of pieces made from a heat of steel,the purchar may require that each piece be individually tested;or,a reprentative method of sampling may be agreed upon by the manufacturer and the purchar.
6.6For the indication of certain internal types of disconti-nuities,such as thermal cracks orflakes,the purchar may specify that disks for macroetch inspection be taken a certain minimum distance from the ends of the specimen.In the ca of forgings,depending upon prior agreement,this may be acco
mplished by adding excess metal for discard on the ends or ends of the forging;or,by forging in multiple lengths and removing the test disk between individual pieces when cutting up the multiple forging.
7.Preparation
7.1Specimen preparation need not be elaborate.Any method of preparing smooth surfaces with a minimum amount of cold work should be satisfactory.Disks may be faced on a lathe or a shaper.The usual procedure is to take a roughing cut, then afinishing cut.This will generate a smooth surface and remove cold work from prior operations.Sharp tools are necessary to produce a good specimen.Grinding,which also may be ud,is usually conducted in the same manner,using free-cutting wheels and light feeds.Whenfine detail must be revealed,the specimen should be prepared with metallographic grinding papers,or even with a metallographic polish.
油泵型号
7.2After specimen preparation,the surface to be etched should be cleaned.Any grea,oil,or other residue will produce an uneven attack and must be removed.It may be necessary to u solvents to clean the surface.Once cleaned, care should be taken to avoid touching or otherwi contami-nating the surface.
7.3Large cross ctions may be cut into smaller pieces to facilitate handling and to comply with safety requirements.The ctioning of the large specimens should be done so as not to disturb the central portion of the ction.
8.Procedure
8.1Macroetching is carried out in containers which must be resistant to the attack of the etching reagent.Small pieces may be etched in glass or porcelain vesls of the types commonly available in laboratories.Larger disks are etched in corrosion-resistant alloy vesls,various types of ceramic pots,rubber-lined kettles or wooden tanks.If metal tanks are ud,lead is most common for containing sulfuric acid solutions while high-nickel iron or high-silicon iron are preferred to contain hydrochloric acid solutions.A nickel-molybdenum alloy can be ud for containing solutions of sulfuric or hydrochloric acid, or both.If the tank is metallic,the disks being etched should not be in contact with each other or with the vesl.Such contact will t up electrolytic(galvanic)couples and will produce an uneven and misleading etch attack.Resins in wood ud to make tanks sometimes act as uncertain and uneven inhibitors resulting in unsatisfactorily etched disks.
8.2Mix the solution and place it in a suitable tray,dish or tank and bring the solution to the desired operating
temperature
before commencing etching.Do not place specimens in a cold solution and then heat it to the desired temperature.The specimens may be placed directly into the solution,but the best practice is to place the specimen in corrosion-resistant baskets or on corrosion-resistant supports,such as glass rods under-neath the specimen to rai it off the bottom of the dish. Maintain a sufficient volume of solution in the vesl to cover the specimen with a layer of at least25mm(1in.)of liquid. When etching is completed,remove the specimen from the solution,taking care not to mar the specimen surface.Remove the smut that forms on the specimen surface by scrubbing the surface with a stiff brush under hot running water.This brush may have natural vegetable or syntheticfibers but not metal fibers.After the smut is removed,rin the specimen under hot running water and blow it dry with compresd air.The specimen should not be blotted dry.The best time for exami-nation is immediately after drying.Dried surfaces may be protected with oil or a transparent lacquer.
8.3Etching time will vary depending on composition,size, whether preheated,or not,etc.Etch the spec
imens to reveal the structure clearly and then remove it from the etch bath. Overetching can lead to misinterpretation.In most cas,15to 30min will be sufficient for hot-acid etching.Etching times with cold solutions(e5.4and5.5)are shorter.
9.Examination of Ingot Cast Product Specimens
9.1After drying(except when using the ammonium persul-fate etchant described in5.4),compare the appearance of the specimen to the photographs in Plate I and report the photo-graph most nearly reprenting the appearance of the specimen in each of the ries.Also report the prence of any of the conditions in Plate II.
9.2Several ries of photographs of etched specimens are prented in two groups.
9.2.1Plate I—Graded ries for three conditions:(1)sub-surface conditions;(2)random conditions;and,(3)center gregation.
9.2.2Plate II—Ungraded ries showing various other con-ditions.
10.Examination of Continuously Cast Product
Specimens
10.1Specimens are examined after etching and drying (except when using the ammonium persulfate etchant de-scribed in5.4).The type of condition prent may be identified by comparison with Plate III.Rating of each condition is accomplished by measurement.Some conditions related to the cast structure(for example,chill zone and columnar structure) may not be discernible in product which has been reduced by rolling and forging while pattern is only discernible in a wrought specimen.
10.2Plate III consists of photographs of macroetched speci-mens showing the typical location and general appearance of conditions found in continuously cast product.Some of the conditions are reprented by sketches drawn on the photo-macrographs.Plate III is ud to identify the type of condition obrved on the macroetch specimens.11.Rating Methods for Continuously Cast Product
Conditions
11.1This ction describes methods for rating conditions in continuously cast product.Conditions to be rated and their level may be established by agreement between the purchar and producer.
11.1.1Linear conditions shown on Plate III are rated as the length of the maximum individual condition prent and are expresd as a percentage of the square root of the transver cross-ctional area of the specimen.
11.1.2Circular conditions shown on Plate III are rated as the diameter of a circle which circumscribes the maximum individual condition and are expresd as a percentage of the square root of the transver cross-ctional area of the specimen.In highly rectangular product,circular conditions may not be compatible with this rating method.In tho cas, circular conditions shall be rated as the average of the maximum length and maximum width of the condition and expresd as a percentage of the square root of the transver area of the specimen.
11.1.3Pinholes are to be rated by counting the number of pinholes prent and expressing the frequency either as pin-holes per unit length or as the total number.
11.1.4White band is to be rated as either prent or not prent.
11.1.5Chill zone is to be rated as either prent or not prent in a continuous layer around the circumference of the product.
11.1.6The equiaxed zone is to be rated as the minimum dimension of the equiaxed zone divided by the minimum ction dimension.
11.1.7If nonmetallic inclusions are obrved during mac-roetch inspection,their size,location and qua
ntity may be noted on the inspection report.Other rating methods may be established per agreement between the ur and producer. 11.1.8Mold slag is rated as either prent or not prent.
马萨诸塞大学
橄榄球英文11.1.9Flakes are rated as either prent or not prent.
12.Report
12.1Report the following information:
12.1.1Date of the test,
12.1.2Name(s)of the personnel performing the test, 12.1.3Identity of the material(heat number,grade,order number,etc.),
12.1.4Location,orientation and identifying numbers of the test specimens,
12.1.5Nature of the disk surface preparation,
john怎么读英语
12.1.6Etching reagent ud,and its temperature,
12.1.7Duration of etching,and
12.1.8Any specifications governing the testing.
12.2Document the type,number,location and orientation of the obrved conditions(e Sections9and10)and the ratings (e Section11)of the measured macrostructural conditions in continuously cast specimens.
12.3List any specific purchar-producer agreements re-garding either the test method or the rating.
put on12.4If sulfur printing was employed,list the details of the test procedure,as defined in Practice E1180
.
13.Precision and Bias
13.1No statement is made about either the precision or the bias of this method for macroetch testing of steel bars,billets, blooms,and forgings since the result merely states whether there is conformance to the criteria for success specified in the procedure.14.Keywords
14.1bars;billets;blooms;bottom-poured ingots;continu-ous casting;forgings;homogeneity;ingots;macroetch;macro-structure;quality control;steel;sulfur printing
ASTM International takes no position respecting the validity of any patent rights asrted in connection with any item mentioned in this standard.Urs of this standard are expressly advid that determination of the validity of any such patent rights,and the risk of 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 everyfive years and if not revid,either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standards and should be addresd to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsible technical committee,which you may attend.If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards,at the address shown below.
人山人海英文This standard is copyrighted by ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959, United States.Individual reprints(single or multiple copies)of this stan
dard may be obtained by contacting ASTM at the above address or at610-832-9585(phone),610-832-9555(fax),or rvice@astm(e-mail);or through the ASTM website
(www.astm).
