ASTM_B_934_-_15.pdf

Designation:B93415Standard Test Method forEffective Case Depth of Ferrous Powder Metallurgy(PM)Parts Using Microindentation Hardness Measurements1This standard is issued under the fixed designation B934;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the 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.1.Scope*1.1 This test method covers a procedure for determinationof the effective case depth of powder metallurgy(PM)parts.1.2 A microindentation hardness traverse procedure is de-scribed to determine effective case depth.This test method maybe used to determine the effective case depth for all types ofhardened cases.1.3 The procedure for determining the microindentationhardness of powder metallurgy materials,as described in TestMethod B933,shall be followed.1.4 With the exception of the unit for density,for which thegrams per cubic centimeter unit is the long-standing industrypractice,the values in SI units are to be regarded as standard.1.5 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 the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2B243 Terminology of Powder MetallurgyB933 Test Method for Microindentation Hardness of PowderMetallurgy(PM)MaterialsE384 Test Method for Knoop and Vickers Hardness ofMaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions of powder metallurgy(PM)terms can befound in Terminology B243.Additional descriptive informa-tion is available in the Related Material section of Volume02.05 of the Annual Book of ASTM Standards.3.2 Definitions of Terms Specific to This Standard:3.2.1 case that portion of a part,extending inward fromthe surface that has a microindentation hardness,afterhardening,equal to or greater than a specified hardness.3.2.2 effective case depthperpendicular distance from thesurface of the hardened case to the furthest point where amicroindentation hardness value equivalent to 50 HRC ismaintained,unless otherwise specified.4.Summary of Test Method4.1 The powder metallurgy part is sectioned and the surfaceprepared for examination.Microindentation hardness measure-ments are taken at various depths below the part surface.Thedistance where the microindentation hardness falls below theequivalent of 50 HRC is defined as the effective case depth,unless otherwise specified.5.Significance and Use5.1 The engineering function of many PM parts may requirean exterior portion of the part to have a specified case depthand microindentation hardness.Measurement of effective casedepth is used to determine the depth to which the microinden-tation hardness of the exterior portion of a part has beenincreased over that of the interior of the part.6.Apparatus6.1 Knoop or Vickers Hardness Indenters,using 100 gf(0.9807 N)loads are recommended following Test MethodE384.The type of hardness indenter and load used shall beagreed upon between customer and producer.6.2 Calibrated Optical Instrument,Micrometer Stage,orother suitable means to measure the distance from the surfaceof the part to the center of the impression with a precision of0.025 mm.7.Test Specimen7.1 Cut a test specimen from the PM part,perpendicular tothe hardened surface at a specified location,being careful toavoid any cutting or grinding procedure that would affect theoriginal microindentation hardness.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.05 on Structural Parts.Current edition approved Oct.1,2015.Published November 2015.Originallyapproved in 2004.Last previous edition approved in 2010 as B934 10.DOI:10.1520/B0934-15.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.2 Mounting of the test specimen is recommended forconvenience in surface preparation,edge retention,and micro-indentation hardness measurement.Edge retention is importantfor proper depth measurement of the case.7.3 Grind and polish the test specimen using methodsrecommended in Appendix X2 of Test Method B933.The areato be traversed should be polished so the microindentationhardness impressions are unaffected,that is,the lighter theindenter load,the finer the finish necessary.Care should betaken to ensure that