ASTM_A_748_-_A_748M_-_87_2012.pdf

Designation:A748/A748M87(Reapproved 2012)Standard Specification forStatically Cast Chilled White Iron-Gray Iron Dual Metal Rollsfor Pressure Vessel Use1This standard is issued under the fixed designation A748/A748M;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.1.Scope1.1 This specification covers statically cast dual metal rollswith the outer layer of the roll body being chilled white iron ofdifferent chemical composition than the core and journals ofthe roll which is gray cast iron.The castings are suitable forpressure containing parts,the design strength of which is basedon the gray iron portion of the cylinder.The castings aresuitable for service at temperatures up to 450F 232C.1.2 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.1.3 The following safety hazards statement pertains only tothe test method portion,9,of this specification:This standarddoes not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations priorto use.2.Referenced Documents2.1 ASTM Standards:2A278/A278M Specification for Gray Iron Castings forPressure-Containing Parts for Temperatures Up to 650F(350C)A667/A667M Specification for Centrifugally Cast DualMetal(Gray and White Cast Iron)Cylinders3.Ordering Information3.1 Orders for material under this specification shall includethe following information:3.1.1 ASTM designation and year of issue,3.1.2 Dimensions of dual rolls,3.1.3 Class of gray iron in the roll core(see 4.2),3.1.4 Inspection requirements,if different(see 10.1),3.1.5 Certification,if required(see 11.1),and3.1.6 Special position of marking information,if required(see 12.1).3.2 Any additional requirements not covered in this speci-fication are subject to agreement between the manufacturer andpurchaser.4.Materials and Manufacture4.1 The melting procedure shall be optional with thefoundry.4.2 The chilled white iron exterior of the roll body shall bemade to a minimum hardness of 60 Scleroscope“C”.The grayiron portion of the roll shall conform to the applicable class ofSpecification A278/A278M,as determined by design require-ments.The scope of this specification shall include Nos.20,25,30,35,150,175,200,and 250 of Specification A278/A278M.4.3 The casting process shall be controlled to produce ametallurgical bond between the chilled white iron exterior andgray iron interior of the roll body.5.Test Requirements5.1 Tensile RequirementsTensile bars removed from aprolongation at one end of the roll journal,in accordance withSpecification A278/A278M,shall have a tensile strength notless than 80%of that specified by the applicable class ofSpecification A278/A278M.5.2 Thickness of Chilled White Iron:5.2.1 The thickness of the clear chilled white iron plus themottled iron at the roll face shall not be more than 30%of thetotal finished wall thickness.5.2.2 The thickness of the chilled white iron exterior of theroll body shall be determined by measuring the chill depth atthe ends of the roll face.6.Finish6.1 All surfaces shall be machined or ground,or both,priorto the rolls being placed into service.1This specification is under the jurisdiction of ASTM Committee A04 on IronCastingsand is the direct responsibility of Subcommittee A04.01 on Grey and WhiteIron Castings.Current edition approved Oct.1,2012.Published November 2012.Originallyapproved in 1977.Last previous edition approved in 2008 as A748/A748M 87(2008).DOI:10.1520/A0748_A0748M-87R12.2For 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 standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Number of Tests7.1 The number of tension tests shall be in accordance withSpecification A278/A278M.8.Specimen Preparation8.1 Test bars representing the gray iron portion of the rollshall be made from a prolongation at one end of the roll journalin accordance with Specification A278/A278M.Tension testspecimens machined from this prolongation shall conform tothe dimensions shown for Specimen“C”in SpecificationA278/A278M.9.Test Method9.1 Tension test specimens shall fit the holders of the testingmachine in such a way that the load shall be axial.The use ofself-aligning shackles is suggested