ASTM E1180-2008(2014) Standard Practice for Preparing Sulfur Prints for Macrostructural Evaluation《宏观结构评估用硫印准备的标准实践规程》.pdf

1、Designation: E1180 08 (Reapproved 2014)Standard Practice forPreparing Sulfur Prints for Macrostructural Evaluation1This standard is issued under the fixed designation E1180; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year

2、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.1. Scope1.1 This practice provides information required to preparesulfur prints (also referred to as Baumann Prints) of mostfer

3、rous 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 notrespond to the test solutions, for example, stee

4、ls 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 compare print image intensities if the images are form

5、edonly 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 basedon the use of the method.1.7 The values sta

6、ted in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.8 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 an

7、d health practices and determine the applica-bility of regulatory limitations prior to use. For specificprecautionary statements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Metallographic SpecimensE7 Terminology Relating to MetallographyE340 Test Method for

8、Macroetching Metals and AlloysE381 Method of Macroetch Testing Steel Bars, Billets,Blooms, and ForgingsE407 Practice for Microetching Metals and Alloys3. Terminology3.1 DefinitionsFor definitions of terms used in thispractice, see Terminology E7.4. Summary of Practice4.1 The sulfur print provides a

9、means for macroscopicevaluation of the sulfur distribution in steels and cast irons bycontact printing using photographic paper soaked in an aque-ous acid solution, for example, sulfuric acid, citric acid, oracetic acid.4.2 The test specimen is usually a disk or rectangularsection, such as used in m

10、acroetch evaluations, cut from anas-cast or wrought specimen with either a transverse orlongitudinal orientation. The specimen is freshly groundsmooth and cleaned to remove cutting oils, scale, abrasives, orother contaminants. The specimen should be at room tempera-ture when sulfur printed.4.3 A she

11、et of photographic paper with (usually) a mattesurface 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, fi

12、xed, washed again in water, and dried as flatas possible.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.5. Significance and Use5.1 The sulfur print reveals the distribution of sul

13、fur 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 used to assess the nature ofd

14、eoxidation, that is, rimming action versus killed steel sulfurdistributions.1This practice is under the jurisdiction of ASTM Committee E04 on Metallog-raphy and is the direct responsibility of Subcommittee E04.01 on SpecimenPreparation.Current edition approved Oct. 1, 2014. Published December 2014.

15、Originallyapproved in 1987. Last previous edition approved in 2008 as E1180 08. DOI:10.1520/E1180-08R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standard

16、s Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.3 Sulfur prints will reveal segregation patterns, includingrefilled cracks, and may reveal certain physical irregularities,for example, poros

17、ity or cracking.5.4 The nature of metal flow, such as 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

18、 acceptance purposes.5.6 The intensity of the sulfur 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 pape

19、r and the ground surface ofthe specimen (this time is 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

20、, acid type and strength, willyield satisfactory prints. 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 wil

21、l not produce useful images.6. Interferences6.1 The specimen 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 re

22、adilyabsorbed by the wet emulsion. The hydrogen sulfide 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 beincorr

23、ectly interpreted as a gross sulfide segregate.6.3 If 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.

24、4 Image blurring may result from movement of the paperduring 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),

25、 the print will belightly colored, even if sulfides are 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, irre

26、spective ofthe sulfur content, if titanium or chromium 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

27、no need to turn off theexisting white lighting, and work 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

28、 wrinkling.7.3 Timing Device, such as used in a photographicdarkroom, is helpful for timing the contact printing time, andthe washing 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 thepri

29、nt; two can be used sequentially for faster fixing 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 drye

30、r very quickly. Clothes lines and cork pegboards will also work but the prints do not dry perfectly flat.8. Reagents and Materials8.1 Photographic paper is a multilayer paper coated with agelatin emulsion containing about 80 mg per square meter ofsilver as a halide (Cl and/or Br) supported by a pape

31、r base thatis nominally single or double weight (110 or 235 g/sq. m). Thespeed and contrast characteristics are of no importance whensulfur printing. The paper base may be fibre base or resincoated. A thin layer of baryta may separate the emulsion andthe base in order to provide a more visible image

32、. A glossyemulsion is preferred to a matte emulsion if image sharpness isimportant; the problem is that a glossy emulsion may slide onthe steel surface and cause blurring. A fibre base is preferred toa resin coated base because the fibre base tends to betterconform to the steel surface; in addition

33、it has less tendency toslip when smoothing the paper over the steel surface. Note thatphoto paper for digital photo printing contains no silver halideemulsion and is not suitable for sulfur printing. The advantageof resin coated photographic paper, over fibre base paper, isthat the paper base is sea

34、led from contact with the dilute acid,the rapid fixer, and the water during washing; hence theprocessing time, including drying time, is much less, especiallyif double weight paper is used. Photographic paper is availablein cut sheets and rolls of various widths. Cut sheets are ideal ifthe specimen

35、size matches the sheet size. Roll dispensed papercan be fed from a “safe” box and cut as needed. The papersheet should be 12 to 20 mm larger than the specimen aroundthe perimeter of the specimen. If the overhang of the paper istoo great then the paper will not lie tight to the edge of thespecimen.8.

36、2 Technical or reagent grade acids, sulfuric acid, aceticacid, citric acid, etc., are used to make the solution in which theE1180 08 (2014)2paper 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 co

37、mmercial photographic fixing solution (rapid fixercontains ammonium thiosulfate rather than sodium thiosulfate)is used to fix the sulfur print image after contact printing andwashing. The fixer should be tested periodically to ensure thatit is still active; set aside a print in the sunlight and if t

38、heappearance changes then the fixer is depleted and should bereplaced. Used fixer contains silver and should be disposed ofin concordance with local regulations. There is not enoughsilver to justify having the silver recovered from the used fixer.9. Hazards9.1 Sulfuric acid, H2SO4, is a highly corro

39、sive, dangerouslyreactive, strong oxidizing agent. It reacts with water releasingsubstantial heat. Add sulfuric acid very slowly to the waterwith constant stirring. Contact with concentrated sulfuric acidmust be avoided. The dilute solution used to soak the prints isnot particularly dangerous but ex

40、posure 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 solution. The other acids recommendedfor sensitizing the paper are less aggressive than sulfuric acid,however, appropriate care sh

41、ould be taken in mixing andhandling.9.2 The reactions during sulfur printing are as follows:H2SO41MnS 5 H2S1MnSO4(1)H2SO41FeS 5 H2S1FeSO4(2)there may be some ferrous sulfide in the steel!H2S12Ag Cl 5 Ag2S12HCl or (3)H2S12AgBr 5 Ag2Br12HCl or both.WarningNote that hydrogen sulfide is released into th

42、eroom. Hydrogen sulfide is toxic and needs to be exhaustedfrom the room if more than a few samples are sulfur printedper 8 hour time period. If you can smell the hydrogen sul-fide then an exhaust system is needed.10. Sampling and Specimens10.1 Samples are generally selected in the same manner andext

43、ent as for macroetching, as described in Methods E3, E340,and E381. Specimens are frequently prepared to represent theentire transverse cross section, in addition, depending on thepurpose of the evaluation; the longitudinal plane may beselected, and while it is usually vertical, it may be horizontal

44、,when required, for example, checking near the 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 appeara

45、nce is not affected by being within the heataffected zone (HAZ) which results from the torch cutting ofcold steel.10.4 Specimens can be thin enough for ease of handling,generally 12 to 25 mm thick, but may be thicker, especially ifbeing prepared on only one side for electrolytical macroetchingafter

46、sulfur printing (40 to 50 mm thick). The surface to becontact printed should be freshly ground until smooth, andcarefully cleaned. Edges should be free of flash, burrs, or scale.10.5 Very smooth surfaces, such as produced by polishing,will promote slippage between the paper and disk resulting inblur

47、red images. A 250 micron (60 grit as packaged) finishprovided by dry grinding with a hand held abrasive grit discsander, or a contact wheel belt sander is satisfactory. Using aface mill may leave tool marks that show up in the sulfur print.Using a (single) wiper insert for the final pass may leave t

48、hesurface so smooth that it must be sanded to make it roughenough for sulfur printing. A vitreous bonded abrasive surfacegrinder may be used as long as the final pass is very light andremoves only 5 micrometer. The surface should be cleanedwith methanol to remove oils and other soils. The final surf

49、aceroughness Ra should be no less than 0.4 micrometer and maybe as large as 1.6 micrometer if the paper tends to slip tooeasily on a smoother surface.10.6 Surface preparation (see Methods E3, E340 and E381)should not produce excessive cold work at the test surface thatcan 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 steel and the desiredprinting time (the reaction is very rapid). AISI 10XX steelswith sulfur contents between