ASTM_A_278_-_A_278M_-_01_2015.pdf

Designation:A278/A278M01(Reapproved 2015)Standard Specification forGray Iron Castings for Pressure-Containing Parts forTemperatures Up to 650F(350C)1This standard is issued under the fixed designation A278/A278M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This specification2covers gray iron for castings suitablefor pressure-containing parts for use at temperatures up to650F(350C).1.2 Classes of Iron:1.2.1 Castings of all classes are suitable for use up to 450F(230C).For temperatures above 450F and up to 650F,onlyClass 40,45,50,55,and 60 castings are suitable.1.2.2 Castings of all classes are suitable for use up to 230C.For temperatures above 230C and up to 350C,only Class275,300,325,350,380,and 415 castings are suitable.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.2.Referenced Documents2.1 ASTM Standards:3A644 Terminology Relating to Iron CastingsE8 Test Methods for Tension Testing of Metallic Materials3.Terminology3.1 Definitions of many terms common to gray iron castingsmay be found in Terminology A644.4.Classification4.1 Classification by tensile strength.4.1.1 Castings ordered to this specification are classifiedbased upon the minimum tensile strength of the iron in ksi,inEnglish units.Class 25 has a minimum specified tensilestrength of 25 ksi.4.1.2 Castings ordered to this specification are classifiedbased upon the minimum tensile strength of the iron in MPa,inMetric units.Class 150 has a minimum specified tensilestrength of 150 MPa.5.Ordering Information5.1 Orders for material in this specification should includethe following information:5.1.1 ASTM designation and year date,5.1.2 Class of iron required and service temperature,5.1.3 Quantity,5.1.4 Heat Treatment:5.1.4.1 Whether or not heat treatment is required for Class40,45,50,55,and 60 castings to be used at temperatures at450F or less(see 6.2),5.1.4.2 Whether or not heat treatment is required for Class275,300,325,350,380,and 415 castings to be used attemperatures at 230C or less(see 6.2),5.1.5 The size of separately cast test bar to be poured(seeSection 9 and Table 1),5.1.6 The size of test specimen to be machined from testbars C or S,and5.1.7 Special requirements.6.Materials and Manufacture6.1 Castings intended for use above 450F(230C)shall bestress-relieved by placing them in a suitable furnace at atemperature not exceeding 400F(200C)and heating themuniformly to the temperatures and for the times specified inTable 2.The heating and cooling rates shall be uniform andshall not be more than 400F/h(250C/h)for castings of 1-in.(25-mm)maximum section.For heavier sections the maximumheating and cooling rates in degrees Fahrenheit per hour shallbe 400 divided by the maximum section thickness.6.2 Heat Treatment and Cooling Rate:6.2.1 Castings of Class Nos.45,50,55,and 60,which are tobe used at temperatures below 450F,may be heat treated in1This specification is under the jurisdiction of ASTM Committee A04 on IronCastings and is the direct responsibility of Subcommittee A04.01 on Grey and WhiteIron Castings.Current edition approved Nov.1,2015.Published November 2015.Originallyapproved in 1944.Last previous edition approved in 2011 as A278/A278M 01(2011).DOI:10.1520/A0278_A0278M-01R15.2For ASME Boiler and Pressure Vessel Code applications see related Specifi-cation SA-278 in Section II of that Code.3For 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 standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 accordance with 6.1 or they shall be cooled in the mold to500F at an average rate of not more than 100F/h for castingsup to 1 in.in section.For heavier sections the maximumcooling rate in degrees Fahrenheit per hour shall be 100divided by the maximum section thickness.6.2.2 Castings of Class Nos.275,300,325,350,380,and415,which are to be used at temperatures below 230C,may beheat treated in accordance with 6.1 or they shall be cooled inthe mold to 250C at an average rate of not more than 50C/hfor castings up to 25-mm in section.For heavier sections themaximum cooling rate in degrees Celsius per hour shall be1250 divided by the maximum section thickness.7.Chemical Composition7.1 Carbon Equivalent:7.1.1 Class 40,45,50,55,and 60 c