ASTM E1180-2003e1 Standard Practice for Preparing Sulfur Prints for Macrostructural Examination《宏观结构检验用硫印准备的标准实施规范》.pdf

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1、Designation: E 1180 03e1Standard Practice forPreparing Sulfur Prints for Macrostructural Examination1This standard is issued under the fixed designation E 1180; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis

2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEEditorial changes were made throughout in October 2003.1. Scope1.1 This practice provides information required to preparesulfur print

3、s (also referred to as Baumann Prints) of mostferrous alloys to reveal the distribution of sulfide inclusions.1.2 The sulfur print reveals the distribution of sulfides insteels with bulk sulfur contents between about 0.010 and 0.40weight percent.1.3 Certain steels contain complex sulfides that do no

4、trespond to the test solutions, for example, steels containingtitanium sulfides or chromium sulfides.1.4 The sulfur print test is a qualitative test. The density ofthe print image should not be used to assess the sulfur contentof a steel. Under carefully controlled conditions, it is possibleto compa

5、re print image intensities if the images are formedonly by manganese sulfides.1.5 The sulfur print image will reveal details of the solidi-fication pattern or metal flow from hot or cold working onappropriately chosen and prepared test specimens.1.6 This practice does not address acceptance criteria

6、 basedon the use of the method.1.7 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-bility of regulatory limitatio

7、ns prior to use. For specificprecautionary statements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2E 3 Methods of Preparation of Metallographic SpecimensE 7 Terminology Relating to MetallographyE 340 Test Method for Macroetching Metals and AlloysE 381 Method of Macroetch Testing Steel B

8、ars, Billets,Blooms, and ForgingsE 407 Test Methods for Microetching Metals and Alloys3. Terminology3.1 DefinitionsFor definitions of terms used in this prac-tice, see Terminology E 7.4. Summary of Practice4.1 The sulfur print provides a means for macroscopicevaluation of the sulfur distribution in

9、steels and cast irons bycontact printing using photographic paper soaked in an aque-ous acid solution, for example, sulfuric acid, citric acid, oracetic acid.NOTE 1No longer are there available emulsion coated half weightfiber based papers suitable for sulfur printing. Emulsion coated singleweight f

10、iber base paper is not readily available. Emulsion coated doubleweight fiber base paper is available, and is preferable to emulsion coatedsingle weight resin coated paper.4.2 The test specimen is usually a disk or rectangularsection, such as used in macroetch evaluations, cut from anas-cast or wroug

11、ht specimen with either a transverse orlongitudinal orientation. The specimen is freshly groundsmooth and cleaned to remove cutting oils, scale, abrasives, orother contaminents. The specimen should be at room tempera-ture when sulfur printed.4.3 A sheet of photographic paper with (usually) a mattesu

12、rface finish of appropriate size is soaked in the diluteaqueous acid solution, any excess liquid removed, and theemulsion side of the paper is placed on the ground surface ofthe specimen. After a suitable time, the paper is removed,washed in water, fixed, washed again in water, and dried as flatas p

13、ossible.4.4 The distribution of sulfur in the specimen is revealed asa mirror image on the photographic paper as darkly coloredareas of silver sulfide embedded in the emulsion.1This practice is under the jurisdiction of ASTM Committee E04 on Metallog-raphy and is the direct responsibility of Subcomm

14、ittee E04.01 on Selection andPreparation of Samples.Current edition approved May 10, 2003. Published July 2003. Originallyapproved in 1987. Last previous edition approved in 1998 as E 1180 94 (1998).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service

15、 at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 The sulfur print rev

16、eals the distribution of sulfur assulfide inclusions in the specimen. The sulfur print comple-ments macroetch methods by providing an additional proce-dure for evaluating the homogeneity of a steel product.5.2 Sulfur prints of as-cast specimens generally reveal thesolidification pattern and may be u

17、sed to assess the nature ofdeoxidation, that is, rimming action versus killed steel sulfurdistributions.5.3 Sulfur prints will reveal segregation patterns, includingrefilled cracks, and may reveal certain physical irregularities,for example, porosity or cracking.5.4 The nature of metal flow, such as

18、 in various forgingoperations, can be revealed using sulfur prints of specimens cutparallel to the metal flow direction.5.5 The sulfur print method is suitable for process control,research and development studies, failure analysis, and formaterial acceptance purposes.5.6 The intensity of the sulfur

19、print is influenced by theconcentration of sulfur in the steel, the chemical compositionof the sulfide inclusions, the aggressiveness of the aqueous acidsolution, and the duration of the contact printing between theacid soaked emulsion coated paper and the ground surface ofthe specimen (this time is

20、 the order of seconds rather thanminutes). Very low sulfur content steels will produce too faintan image to be useful for macrostructural evaluations. Selec-tion of appropriate printing practices including selection oftype of emulsion coated media, acid type and strength, willyield satisfactory prin

21、ts. Very faint images in the sulfur printcan be made more visible by scanning the sulfur print into aPC, and using a photo editor to increase the color saturation.Steels with compositions that produce predominantly titaniumor chromium sulfides will not produce useful images.6. Interferences6.1 The s

22、pecimen must be properly cleaned, otherwise darkspots will be produced which may be incorrectly interpreted asa gross sulfide segregate.6.2 Hydrogen sulfide gas is produced while the paper is incontact with the specimen. The hydrogen sulfide is readilyabsorbed by the wet emulsion. The hydrogen sulfi

23、de reactswith the silver halides in the emulsion to lay down insolublesilver sulfide. If the specimen contains pores or cracks,hydrogen sulfide gas may become entrapped in these openingsand may produce a brown color on the paper which may beincorrectly interpreted as a gross sulfide segregate.6.3 If

24、 air is entrapped between the contacting paper andspecimen, and is not removed, a white spot may be producedon the print. Air entrapment must be quickly removed by theuse of a rubber squeegee or roller to move bubbles to the edgeof the specimen.6.4 Image blurring may result from movement of the pape

25、rduring contact.6.5 Specimens with low sulfur contents are often pre-etchedbefore printing to expose more sulfides and enhance the image.If the pre-etchant contains sulfate ions (for example, a stainlesssteel specimen etched with Marbles reagent), the print will belightly colored, even if sulfides a

26、re not present in the steel.Such etchants should not be used for this purpose.6.6 If chromium replaces some of the manganese in thesulfide inclusions, the print intensity for a given sulfur levelwill be reduced. An image will not be obtained, irrespective ofthe sulfur content, if titanium or chromiu

27、m sulfides are present.7. Apparatus7.1 LightingIf the chosen photographic paper when ex-posed to the existing room light for 15 min changes from whiteto light blue and then clears back to white when processed inthe sequence of solutions, there is no need to turn off theexisting white lighting, and w

28、ork under amber bulb lighting;never expose the paper to sunlight.7.2 Shallow Container, such as a photographic tray, isrequired to contain the dilute aqueous acid solution. Thecontainer must be large enough to soak the emulsion coatedpaper without wrinkling.7.3 Timing Device, such as used in a photo

29、graphic dark-room, is helpful for timing the contact printing time, and thewashing and fixing periods.7.4 Tank, of suitable size with cool flowing water, isrequired for washing the print.7.5 Tank, or Covered Tray, to hold the fixing agent and theprint; two can be used sequentially for faster fixing

30、when usingemulsion coated double weight fiber based paper.7.6 DryingHeated drum dryers are no longer made.Heated drying cabinets are available for fiber base prints laidhorizontally on a screen. Resin coated papers can be dried withan infra red dryer very quickly. Clothes lines and cork pegboards wi

31、ll also work but the prints do not dry perfectly flat.8. Reagents and Materials8.1 Photographic enlarging paper with a matte finish and afiber base is preferred. Sharper images are produced by the useof glossy photographic printing paper. Due to the smoothsurface finish, it is difficult to prevent b

32、lurring of the image.Resin-coated paper when used with small area specimens canproduce satisfactory results; as the area gets larger it becomesmore difficult to have the paper conform to the specimensurface, because the paper base is coated with a thin layer ofpolyethylene which does not absorb any

33、water and becomesufficiently limp, as with fiber base paper. Photographic paperis available in cut sheets and rolls of various widths. Cut sheetsare ideal if the specimen size matches the sheet size. Rolldispensed paper can be fed from a “safe” box and cut asneeded. The paper sheet should be 12 to 2

34、0 mm (12 to34 in.)larger than the specimen around the perimeter of the specimen.If the overhang of the paper is too great then the paper will notlie tight to the edge of the specimen.8.2 Technical or reagent grade acids, sulfuric acid, aceticacid, citric acid, etc., are used to make the solution in

35、which thepaper is soaked prior to contact printing; typical concentrationsof acid are 2 to 10 % sulfuric acid, 10 to 15 % acetic acid, and10 to 15 % citric acid.8.3 A commercial photographic fixing solution (a liquidrapid fixer) is used to fix the sulfur print image after contactprinting and washing

36、. The fixer should be tested periodically toensure that it is still active; set aside a print in the sunlight andE118003e12if the appearance changes then the fixer is deleted and shouldbe replaced. Used fixer contains silver and should be disposedof in concordance with local regulations. There is no

37、t enoughsilver to justify having the silver recovered from the used fixer.9. Hazards9.1 Sulfuric acid, H2SO4, is a highly corrosive, dangerouslyreactive, strong oxidizing agent. It reacts with water releasingsubstantial heat. Add sulfuric acid very slowly to the waterwith constant stirring. Contact

38、with concentrated sulfuric acidmust be avoided. The dilute solution used to soak the prints isnot particularly dangerous but exposure to it should be mini-mized and hands should be washed after any contact. The useof rubber gloves should be considered. Use tongs to handle thepaper in the soaking sol

39、ution. The other acids recommendedfor sensitizing the paper are less aggressive than sulfuric acid,however, appropriate care should be taken in mixing andhandling.10. Sampling and Specimens10.1 Samples are generally selected in the same manner andextent as for macroetching, as described in Methods E

40、 3,E 340, and E 381. Specimens are frequently prepared torepresent the entire transverse cross section, in addition,depending on the purpose of the examination; the longitudinalplane may be selected, and while it is usually vertical, it maybe horizontal, when required, for example, checking near the

41、edge of a slab.10.2 The number, orientation, and location of specimensmay be subject to producer-purchaser agreement.10.3 Specimens should be cut in a region away from anyeffects from hot shearing or burning; unlike macroetching, thesulfur print appearance is not affected by being within the heataff

42、ected zone (HAZ) which results from torch cutting.10.4 Specimens can be thin enough for ease of handling,generally 12 to 25 mm (0.5 to 1 in.) thick, but may thicker,especially if being prepared on only one side for electrolyticalmacroetching after sulfur printing (40 to 50 mm (1.6 to 2.0 in.)thick).

43、 The surface to be contact printed should be freshlyground until smooth, and carefully cleaned. Edges should befree of flash, burrs, or scale.10.5 Very smooth surfaces, such as produced by polishing,will promote slippage between the paper and disk resulting inblurred images.10.6 Surface preparation

44、(see Methods E 3, E 340 andE 381) should not produce excessive cold work at the testsurface that can close up voids and cracks.11. Procedure11.1 Soak the photographic paper in the selected aqueousacid solution. The strength of the solution will depend upon theacid selected, the sulfur content of the

45、 steel and the desiredprinting time (the reaction is very rapid). AISI 10XX steelswith sulfur contents between 0.015 wt % and 0.035 wt % aretypically printed using a 2 % sulfuric acid solution. AISI 11XXseries steels are more successfully printed with a 15 % citricacid solution. Steels with low sulf

46、ur contents (under 0.010wt %) may be printed using 5 to 10 % sulfuric acid solutions.When large size prints are desired, a longer working time maybe required, necessitating a weaker acid solution.11.2 Soak the paper in the solution for 1 to 5 min. A 3-minsoak time is commonly used. Periods in excess

47、 of 5 min maycause swelling of the emulsion. The tendency of the paper tocurl must be removed and the paper must become very limp.11.3 After soaking the required time, remove the paper fromthe solution and allow excess solution to drip off the paper intothe bath. To minimize paper movement during pr

48、inting, it maybe advisable to place the paper on a glass plate and removeexcess liquid with a rubber roller or squeegee.11.4 When the paper surface is relatively dry, lay the paper,emulsion side down, on the clean, ground surface of thespecimen.11.5 Any air bubbles between the test piece and paper m

49、ustbe carefully moved off to the edge of the sample using a roller,squeegee, sponge, or paper towel soaked in the aqueoussulfuric acid solution. This must be done carefully so that thepaper does not move.11.6 The emulsion side of the paper is kept in contact withthe ground surface of the test piece for 30 s to 10 min,depending on the acid selected, the concentration of the acidsolution, and the sulfur content of the steel.11.7 When comparing test results for relatively similarspecimens, it is best to standardize the selection of acid and theconcentration of the bath, the soak