ASTM C774-88 (R2021) pdf free download.Standard Test Method for Yield Strength of Enameling Steels After Straining and Firing.
1 .1 This test method covers determination of the yield strength of steel specimens after simulated forming and enamel tiring operations.
1 .2 The values stated in inch-pound units are to he regarded as the standard. The values given in parentheses are for information only.
3. Definition
3. 1 quarter lines—imaginary lines parallel to the direction of rolling, positioned at a distance from the sheet mill edge equal to one quarter of the sheet width.
4. Summary of Test Method
4. 1 Representative sheet-steel specimens are selected, strained in tension to simulate forming. heat treated to simulate enamel firing, and tension tested for determination of yield strength.
5. Significance and Use
5.1 In the manufacture of porcelain enameled ware, sheet steel is subjected to forming operations and subsequently to firing of the enamel at temperatures, typically, of 1400 to 1550 °F (760 to 844 °C). Some steels used for porcelain enameling are subject to grain growth in critically strained areas resulting in loss of strength.
5.2 This may lead to easy deformation of the steel and damage to the porcelain enamel coating.
5.3 This test method may he correlated with transit or use tests to evaluate the suitability of steel for porcelain enameled ware.
6. Apparatus
6. 1 Shear for cutting blanks.
6.2 Equipment for cutting or machining tension specimens.
6.3 Gage, 2-in. (50.8-mm), for marking tension specimens.
6.4 Tension-Testing Equipment, as described in Test Methods and Definitions A370.
6.5 Specimen-Supporting Rack, slotted to support specimens on edge spaced 1 in. (25.4 mm) apart.
6.6 Furnace, capable of heating the test specimens and their supporting rack to the tIring temperature in 2 mm.
7. Reagents and Materials
7.1 Sheet Steel, sufficient in size to provide the test specimen, described in Section 8.
7.2 Solvent, such as acetone or isopropyl alcohol.
7.3 Hydrochloric Acid (1+1)—Dilute 1 volume of concen - trated hydrochloric acid (HC1, sp gr 1.19) with I volume of water.
8. Sampling
8.1 Obtain ten test samples, each approximately 1 by 9 in. (25 by 229 mm), from within the quarter lines of the sheet sample, the long dimension being in the direction of rolling.
9. Procedure
9. I Remove burrs from the cut edges of the test samples.
9.2 Mark 2-in. (50.8-mm) gage lengths in the middle of the test samples and strain in tension. Maintain a minimum of I in. (25.4 mm) of length between the grips of the tension-testing machine and the gage marks.ASTM C774 pdf download.