1、Designation: C774 88 (Reapproved 2016)Standard Test Method forYield Strength of Enameling Steels After Straining andFiring1This standard is issued under the fixed designation C774; 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.INTRODUCTIONThe strength after strain and fire of a steel is a significant factor in the strength of the final enameledw
3、are. This test provides a method to quantify the yield strength of enamel steels after straining andfiring by straining duplicate test plates to five different strain levels, exposing to a simulated enamelfire, and measuring the yield stress with a standardized tensile pull test.1. Scope1.1 This tes
4、t method covers determination of the yieldstrength of steel specimens after simulated forming and enamelfiring operations.1.2 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.3 This standard does not purport to address
5、 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A370 Test Methods
6、 and Definitions for Mechanical Testingof Steel ProductsE8 Test Methods for Tension Testing of Metallic Materials3. Definition3.1 quarter linesimaginary lines parallel to the directionof rolling, positioned at a distance from the sheet mill edgeequal to one quarter of the sheet width.4. Summary of T
7、est Method4.1 Representative sheet-steel specimens are selected,strained in tension to simulate forming, heat treated to simulateenamel firing, and tension tested for determination of yieldstrength.5. Significance and Use5.1 In the manufacture of porcelain enameled ware, sheetsteel is subjected to f
8、orming operations and subsequently tofiring of the enamel at temperatures, typically, of 1400 to1550F (760 to 844C). Some steels used for porcelainenameling are subject to grain growth in critically strainedareas resulting in loss of strength.5.2 This may lead to easy deformation of the steel anddam
9、age to the porcelain enamel coating.5.3 This test method may be correlated with transit or usetests to evaluate the suitability of steel for porcelain enameledware.6. Apparatus6.1 Shear for cutting blanks.6.2 Equipment for cutting or machining tension specimens.6.3 Gage, 2-in. (50.8-mm), for marking
10、 tension specimens.6.4 Tension-Testing Equipment, as described in Test Meth-ods and Definitions A370.6.5 Specimen-Supporting Rack, slotted to support speci-mens on edge spaced 1 in. (25.4 mm) apart.6.6 Furnace, capable of heating the test specimens and theirsupporting rack to the firing temperature
11、in 2 min.7. Reagents and Materials7.1 Sheet Steel, sufficient in size to provide the testspecimen, described in Section 8.1This test method is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatingsand is the direct responsibility of Subcommittee B08.12 onMaterials for Porcela
12、in Enamel and Ceramic-Metal Systems.Current edition approved Nov. 1, 2016. Published November 2016. Originallyapproved in 1974. Last previous edition approved in 2011 as C774 88(2011)1.DOI: 10.1520/C0774-88R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custo
13、mer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17.2 Solvent, such as acetone or isopr
14、opyl alcohol.7.3 Hydrochloric Acid (1+1)Dilute 1 volume of concen-trated hydrochloric acid (HCl, sp gr 1.19) with 1 volume ofwater.8. Sampling8.1 Obtain ten test samples, each approximately 1 by 9 in.(25 by 229 mm), from within the quarter lines of the sheetsample, the long dimension being in the di
15、rection of rolling.9. Procedure9.1 Remove burrs from the cut edges of the test samples.9.2 Mark 2-in. (50.8-mm) gage lengths in the middle of thetest samples and strain in tension. Maintain a minimum of 1 in.(25.4 mm) of length between the grips of the tension-testingmachine and the gage marks.9.3 E
16、longate duplicate test samples to nominal strain levelsof 0, 8, 12, 16, and 20 %. Measure the elongation withextensometers, dividers, or other means.9.4 Remove the test samples from the tension machine andmeasure actual strain to the nearest 0.01 in. (0.25 mm).9.5 Clean the strained test samples wit
17、h the solvent and firein air atmosphere at 1450 6 10F (788 6 5C) for 4 min. Testsamples may be hung from hooks or supported on edge spaced1 in. (25.4 mm) apart (if the latter, be sure to support in amanner to prevent sagging during firing). The test samplesshould reach the firing temperature within
18、2.0 6 0.5 min.9.6 Remove the samples from the furnace and air cool.9.7 Descale the fired samples in a HCl (1+1) solutioncontaining a few drops of an inhibitor, such as formaldehyde,at a temperature of 70 to 100F (21 to 38C). Promptly rinsethe test samples and dry.9.8 Machine the descaled test sample
19、s to make standardrectangular tension tests specimens in accordance with TestMethods and Definitions A370. The specimens shall have aminimum length of 8 in. (204 mm) and the sides of the reducedsection shall be parallel.9.9 Measure the thickness and width of each specimen, andtest for yield strength
20、 as described in Test Methods E8 at acrosshead speed of 0.10 in. (2.5 mm)/min. Determine the yieldstrength at the lower point or by the 0.5 % extension underload.10. Report10.1 Report the yield strengths determined for the duplicatespecimens at each of the five strain levels.10.2 Report the actual s
21、train imparted to each specimen.11. Precision and Bias11.1 The precision and bias of yield strength and strain inthis test method would be identical to the precision and bias ofTest Methods E8. Refer to this standard for up-to-date preci-sion and bias.ASTM International takes no position respecting
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25、 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 by 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:/ 88 (2016)2
