ASTM_B_312_-_14.pdf

Designation:B31214Standard Test Method forGreen Strength of Specimens Compacted from MetalPowders1This standard is issued under the fixed designation B312;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 standard covers a test method that may be used tomeasure the transverse rupture strength of a compacted butunsintered(green)test specimen produced from lubricated orunlubricated metal powders or powder mixtures.1.2 Green strength is measured by a quantitative laboratoryprocedure in which the fracture strength is calculated from theforce required to break an unsintered test specimen supportedas a simple beam while subjected to a uniformly increasingthree-point transverse load under controlled conditions.1.3 This test method is a companion standard to TestMethod B528 that covers the measurement of the transverserupture strength of sintered PM test specimens.1.4 With the exception of the values for density and themass used to determine density,for which the use of the gramper cubic centimeter(g/cm3)and gram(g)units is the long-standing industry practice,the values in inch-pound units are tobe regarded as standard.The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered 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:2B215 Practices for Sampling Metal PowdersB243 Terminology of Powder MetallurgyB528 Test Method for Transverse Rupture Strength of Pow-der Metallurgy(PM)SpecimensB925 Practices for Production and Preparation of PowderMetallurgy(PM)Test SpecimensB962 Test Methods for Density of Compacted or SinteredPowder Metallurgy(PM)Products Using ArchimedesPrincipleE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitionsthe definitions of powder metallurgy(PM)terms used in this test method can be found in TerminologyB243.Additional descriptive PM information is available inthe Related Material section of Vol 02.05 of the Annual Bookof ASTM Standards.4.Summary of Test Method4.1 Three rectangular test specimens are compacted to apredetermined green density or at a specified compactingpressure from test portions of the metal powder or powdermixture that is to be tested.4.2 Each unsintered bar is placed,in turn,in a test fixtureand subjected to a uniformly increasing transverse load undercontrolled conditions until fracture occurs.4.3 The green strength or maximum flexural stress of eachspecimen is determined by calculation using the stress equationfor a simply supported beam with a concentrated mid-pointload.4.4 The green strength of the material being tested isreported as the arithmetic mean of the results of three indi-vidual tests at the measured green density or at the specifiedcompacting pressure rounded to the nearest 100 psi(0.5 MPa).5.Significance and Use5.1 The green strength value determined under the condi-tions specified by this test method is influenced by thecharacteristics of the powder,how it compacts under thespecified conditions(i.e.,the particle to particle bonding thatexists following compacting),and the lubrication system used.5.2 Knowledge of the green strength value is useful to theproduction,characterization and utilization of metal powdersin the manufacture of PM structural parts and bearings.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 B09.02 on Base Metal Powders.Current edition approved June 1,2014.Published July 2014.Originally approvedin 1956.Last previous edition approved in 2009 as B312 09.DOI:10.1520/B0312-14.2For 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 5.3 The test for green strength of a compacted metal powdercan be used to:5.3.1 Relate the resistance of a pressed compact to breakageor damage due to handling.5.3.2 Compare the quality of a metal powder or powdermixture from lot to lot.5.3.3 Determine the effect of the addition of a lubricant orother powders to a base powder.5.3.4 Evaluate powder mixing or blending variables.5.4Factors tha