1、Designation:A 438 80(Reapproved 1997)Standard Test Method forTransverse Testing of Gray Cast Iron1This standard is issued under the fixed designation A 438;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A n
2、umber in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope1.1 This test method covers a procedure for performingtransver
3、se bending tests on separately cast cylindrical test barsof gray cast iron.1.2 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 t
4、he applica-bility of regulatory limitations prior to use.2.Significance and Use2.1 A transverse bending test on an unmachined test bar ofgray cast iron is useful as a rapid and inexpensive means forestimating the approximate strength of the test bar,but is not adependable substitute for a tension te
5、st on a machined speci-men(Explanatory Note 1).The test yields easily measureddeflection values which are useful for comparing the relativeductilities of different test bars of gray cast iron(ExplanatoryNote 2).The test can also be used to calculate a modulus ofrupture or an apparent modulus of elas
6、ticity(Explanatory Note3).3.Dimensions and Form of Test Bars3.1 The test bars shall be separate castings of essentiallycylindrical shape(Explanatory Note 4),and available in threestandard sizes as shown in Fig.1(Explanatory Note 5).Theymay contain a reasonable amount of pattern draft,but thediameter
7、 at the middle of the test bar shall be within thetolerances given in Fig.1.3.2 Molds for the test bars shall be approximately at roomtemperature when poured.The test bars shall be cooled in themold to a temperature less than 900F(490C),and then maybe cooled in still air to room temperature.4.Proced
8、ure4.1 Perform the transverse test on a bar in the as-cast(unmachined)condition,loading the bar as a simple beam withthe load applied midway between the supports as shown in Fig.1.The supports and the loading fixture shall be designed togive essentially point contact with the test bar.Satisfactoryco
9、ntact is considered to exist when the supports and loadingfixture have a cylindrical surface with a diameter of about14to1 in.(6.4 to 25.4 mm)and when this surface is positionednormal to the length of the test bar.4.1.1 Round bars are those whose minimum and maximumdiameters,at the middle of the len
10、gth of the bars,differ by lessthan 0.025 in.(0.64 mm)for test bar A and by less than 0.050in.(1.27 mm)for test bars B and C.Determine the reportedbreaking load,in pounds,for round bars by dividing the actualbreaking load by a correction factor(Table 1),entering thetable with the arithmetic average o
11、f the minimum diameters ofthe bar.The load is to be applied in line with the minimumdiameter.4.1.2 Elliptical bars are those whose minimum and maxi-mum diameters,at the middle of the length of the bar,differ bymore than 0.025 in.(0.64 mm)for test bar A or 0.050 in.(1.27mm)for test bars B and C.For e
12、lliptical bars,apply the load inline with the minimum diameter.Determine the reportedbreaking load,in pounds,by dividing the actual breaking loadby a correction factor(Table 1)entering the table with theminimum diameter.1This method is under the jurisdiction of ASTM Committee A04 on IronCastings and
13、 is the direct responsibility of Subcommittee A04.21 on Testing.Current edition approved March 28,1980.Published July 1980.Originallypublished as A 438 60 T.Last previous edition A 438 62(1974).1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United Sta
14、tes.NOTICE:This standard has either been superceded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.EXPLANATORY NOTESNOTE1The approximate general relationship between the tensilestrength of gray cast iron and the corrected transverse b
15、reaking load asdetermined by this test method is given in Table 2.NOTE2It is recommended that deflections at fracture be measured,corrected,and recorded.Correction for deviation of a test bar from thenominal diameter is made by dividing the observed deflection by thecorrection factors listed in Tabl
16、e 1 corresponding to the diameter in thedirection of the line of the load.The diameter should be measured at thefracture surface.Enter Table 1 with the minimum diameter.NOTE3The modulus of rupture for a round test bar tested inaccordance with this test method can be calculated as follows:Modulus of rupture,psi 5 2.55 SL/D3(1)where:S=breaking load,lbf,L=distance between supports,in.,andD=actual diameter of round test bar,in.The apparent modulus of elasticity for a round test bar tested according
