ASTM_B_243_-_16a.pdf

Designation:B24316aStandard Terminology ofPowder Metallurgy1This standard is issued under the fixed designation B243;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.Scope1.1 This terminology standard includes definitions that arehelpful in the interpretation and application of powder metal-lurgy terms.2.Referenced Documents2.1 ASTM Standards:B331 Test Method for Compressibility of Metal Powders inUniaxial Compaction3.Terminology3.1 Definitions:acicular powder,nneedle-shaped particles.activated sintering,va sintering process during which therate of sintering is increased,for example,by addition of asubstance to the powder or by changing sintering conditions.agglomerate,nseveral particles adhering together.air classification,nthe separation of powder into particlesize fractions by means of an air stream of controlledvelocity.angle of repose,nthe basal angle of a pile formed by powderwhen freely poured under specified conditions onto a hori-zontal surface.apparent density,nthe mass of a unit volume of powder,usually expressed as grams per cubic centimetre,determinedby a specified method.apparent hardness,nthe hardness of a PM material(includ-ing the effects of porosity),measured using macroindenta-tion hardness equipment.DISCUSSIONSee general description of production,properties,anduses of sintered metal powder bearings and structural parts,paragraphon density and mechanical properties,information on hardnessmeasurement,Volume 02.05.2apparent porosity,nspecific to cemented carbides,micro-structural features that appear to be pores in a properlyprepared,unetched surface;these features may result fromuncombined carbon or nonmetallic inclusions as well asactual porosity.atomization,nthe dispersion of a molten metal into particlesby a rapidly moving gas or liquid stream or by mechanicalmeans.atomized metal powder,nmetal powder produced by thedispersion of a molten metal by a rapidly moving gas,orliquid stream,or by mechanical dispersionblank,na pressed,presintered,or fully sintered compact,usually in the unfinished condition,requiring cutting,machining,or some other operation to give it its final shape.blending,nthe thorough intermingling of powders of thesame nominal composition(not to be confused with mixing).blister crack,ntypically small defects(star burst)over oraround a bump or blister.DISCUSSIONThese may occur during sintering as a result of rapidoutgassing of the lubricant.The rapid outgassing may be caused by thespecified amount of lubricant being subjected to an excessive heatingrate.The defects may also be caused by“concentrated balls”oflubricant,or moisture.During the sintering of the copper base PMparts,hydrogen gas from the furnace atmosphere can diffuse into thecompact and react with residual oxygen,producing steam that can formblisters and cracks.In that industry,this is also called embrittlement,and is not to be confused with the hydrogen embrittlement of highstrength steel.blistered compact,na sintered object characterized byhaving blisters or eruptions on the surface.DISCUSSIONIn ferrous materials,this effect is often caused by in situgas decomposition and soot formation that forces particles apart andcauses the compact to blister.1This terminology is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcommit-tee B09.01 on Nomenclature and Technical Data.Current edition approved Dec.1,2016.Published February 2017.Originallyapproved in 1949.Last previous edition approved in 2016 as B243 16.DOI:10.1520/B0243-16A.2For a discussion of apparent hardness,see the section on Density in GeneralDescription of Production,Properties,and Uses of Sintered Metal Powder Bearingsand Structural Parts,which appears in the Annual Book of ASTM Standards,Vol02.05.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 binder,na cementing medium;either a material added to thepowder to increase the green strength of the compact,andwhich is expelled during sintering;or a material(usually ofrelatively lower melting point)added to a powder mixturefor the specific purpose of cementing together powderparticles which alone would not sinter into a strong body.binder(MIM),na mixture of polymers or other materials,orboth,that when combined with metal powders enables themixture to flow during the injection molding process.Thebinder imparts green strengt