1、Designation: B243 18B243 19Standard 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 indica
2、tes 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 are helpful in the interpretation and application of powder metallurgyterms.1.2 This international standard was
3、 developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced D
4、ocuments2.1 ASTM Standards:B331 Test Method for Compressibility of Metal Powders in Uniaxial Compaction3. Terminology3.1 Definitions:acicular powder, nneedle-shaped particles.activated sintering, vna sintering process during which the rate of sintering is increased, for example, by addition of asubs
5、tance to the powder or by changing sintering conditions.agglomerate, nseveral particles adhering together.air classification, nthe separation of powder into particle size fractions by means of an air stream of controlled velocity.angle of repose, nthe basal angle of a pile formed by powder when free
6、ly poured under specified conditions onto a horizontalsurface.apparent density, nthe mass of a unit volume of powder, usually expressed as grams per cubic centimetre, determined by aspecified method.apparent hardness, nthe hardness of a PM material (including the effects of porosity), measured using
7、 macroindentationhardness equipment.DISCUSSIONSee general description of production, properties, and uses of sintered metal powder bearings and structural parts, paragraph on density and mechanicalproperties, information on hardness measurement, Volume 02.05.2apparent porosity, nspecific to cemented
8、 carbides, microstructural features that appear to be pores in a properly prepared,unetched surface; these features may result from uncombined carbon or nonmetallic inclusions as well as actual porosity.atomization, nthe dispersion of a molten metal into particles by a rapidly moving gas or liquid s
9、tream or by mechanical means.atomized metal powder, nmetal powder produced by the dispersion of a molten metal by a rapidly moving gas, or liquid stream,or by mechanical dispersion1 This terminology is under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and is the
10、 direct responsibility of SubcommitteeB09.01 on Nomenclature and Technical Data.Current edition approved Oct. 1, 2018Jan. 1, 2019. Published January 2019. Originally approved in 1949. Last previous edition approved in 20172018 asB243 17.B243 18. DOI: 10.1520/B0243-18.10.1520/B0243-19.2 For a discuss
11、ion of apparent hardness, see the section on Density in General Description of Production, Properties, and Uses of Sintered Metal Powder Bearings andStructural Parts, which appears in the Annual Book of ASTM Standards, Vol 02.05.This document is not an ASTM standard and is intended only to provide t
12、he user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the stand
13、ard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1binder, na cementing medium; either a material added to the powder to increase the green strength of the compact, and w
14、hichis expelled during sintering; or a material (usually of relatively lower melting point) added to a powder mixture for the specificpurpose of cementing together powder particles which alone would not sinter into a strong body.binder (MIM), na mixture of polymers or other materials, or both, that
15、when combined with metal powders enables the mixtureto flow during the injection molding process. The binder imparts green strength to the MIM part and allows it to retain its moldedshape.binder removal, nthe chemical or thermal extraction of binder from a compact. Synonymous with debinding.blank, n
16、a pressed, presintered, or fully sintered compact, usually in the unfinished condition, requiring cutting, machining, orsome other operation to give it its final shape.blending, nthe thorough intermingling of powders of the same nominal composition (not to be confused with mixing).blister crack, nty
17、pically small defects (star burst) over or around a bump or blister.DISCUSSIONThese may occur during sintering as a result of rapid outgassing of the lubricant. The rapid outgassing may be caused by the specified amount oflubricant being subjected to an excessive heating rate. The defects may also b
18、e caused by “concentrated balls” of lubricant, or moisture. During thesintering of the copper base PM parts, hydrogen gas from the furnace atmosphere can diffuse into the compact and react with residual oxygen,producing steam that can form blisters and cracks. In that industry, this is also called e
19、mbrittlement, and is not to be confused with the hydrogenembrittlement of high strength steel.blistered compact, na sintered object characterized by having blisters or eruptions on the surface.DISCUSSIONIn ferrous materials, this effect is often caused by in situ gas decomposition and soot formation
20、 that forces particles apart and causes the compact toblister.bridging, vnthe formation of arched cavities in a powder mass.briquet, nsee compact.brown part, nan MIM part that has had a majority of the binder (first stage) removed. Synonymous with debound part.bulk density, nthe mass per unit volume
21、 of a powder under nonstandard conditions, for example, in a shipping container (notto be confused with apparent density).burn-off, nremoval of organic additives (binder or lubricant) from a compact by heating.cake, na bonded mass of unpressed metal powder.DISCUSSIONOften refers to the form of powde
22、r as it exits a furnace.carbonyl powder, na metal powder prepared by the thermal decomposition of a metal carbonylcavity (MIM), nthe hollow space of a mold that forms one part.cemented carbide, nsintered material characterized by high strength and wear resistance and comprising one or more carbideso
23、f refractory metals as the main component bonded by metallic binder phase.cermet, nsintered material containing at least one metallic phase and at least one nonmetallic phase that is generally of a ceramicnature.chemical deposition, nthe precipitation of one metal from a solution of its salts by the
24、 addition of another metal or reagent tothe solution.chemically precipitated metal powder, npowder produced by the reduction of a metal from a solution of its salts either by theaddition of another metal higher in the electromotive series or by other reducing agent.classification, nseparation of a p
25、owder into fractions according to particle size.closed pore, na pore not communicating or connected with an exterior surface.B243 192coin, vto repress a sintered compact to obtain a definite surface configuration. Synonymous with emboss (not to be confused withrestrike or size).cold isostatic pressi
26、ng, pressing (CIP), nthe pressing of a powder, compact, or sintered object by subjecting it, at ambienttemperature, to nominally equal pressure from every direction.isostatic pressing at ambient temperature.cold pressing, nthe forming of a compact at room temperature.cold welding, ncohesion between
27、two surfaces of metal, generally under the influence of externally applied pressure, at roomtemperature.DISCUSSIONOften used to describe the mechanism by which powder particles develop initial bonds and a pressed compact develops green minuted powder, na powder produced by mechanical attrition of so
28、lid metal or powdercommunicating pores, nsee interconnected pact, nan object produced by the compression of metal powder, generally while confined in a die, with or without theinclusion of nonmetallic constituents. Synonymous with pactibility, na conceptual term, encompassing the powder characterist
29、ics of compressibility, green strength, edge retention,and lamination tendency, that relates to the ability of a powder to be consolidated into a usable green pacting, na process in which a powder held in a die or other container is subjected to an external force in order to densifythe powder and pr
30、oduce a compact of prescribed shape and pacting pressure (uniaxial), napplied force divided by the projected area of contact with the punch(es).compacting tool set, nan assembly of tooling items in which powder is pressed.DISCUSSIONMay include a die, punches, and core pletely alloyed powder, nsee pr
31、e-alloyed posite compact, na metal powder compact consisting of two or more adhering layers, rings, or other shapes of differentmetals or alloys with each material retaining its original posite powder, na powder in which each particle consists of two or more distinct pound compact, na metal powder c
32、ompact consisting of mixed metals, the particles of which are joined by pressing orsintering, or both, with each metal particle retaining substantially its original pounding (MIM), nprocess whereby the metal powders and molten binder constituents are combined to produce pressibility, nthe capacity o
33、f a metal powder to be densified under a uniaxially applied pressure in a closed die.DISCUSSIONCompressibility is measured in accordance with Test Method B331 and may be expressed numerically as the pressure to reach a specified density, oralternatively the density at a given pressure.3compression r
34、atio, nthe ratio of the volume of the loose powder to the volume of the compact made from it. Synonymous withfill ratio.continuous sintering, vnpresintering, or sintering, in such manner that the objects are advanced through the furnace at a fixedrate by manual or mechanical means. Synonymous with s
35、toking.cooling rate, nthe average temperature change per second between prescribed temperatures during the cooling phase of athermal process.3 See Test Method B331.B243 193core rod, na member of the compacting tool set that forms internal features such as splines, diameters, keyways, or other profil
36、esin a PM compact.cored bar, na compact of bar shape heated by its own electrical resistance to a temperature high enough to melt its interior.crack (RD), ngenerally a planar defect.cracked ammonia, nsee dissociated ammonia.cracks (rigid die system (RD), nthe following names and definitions apply on
37、ly to items produced in a rigid die system (RD)as opposed to those cracks produced by other systems, that is, metal injection molding, vacuum hot pressing, and so forth.4cross-product contamination, nthe unintentional mixing of powders with distinct differences in either physical characteristicsor c
38、hemical composition or both.cut, nsee fraction.debinding, nsee binder removal.debound part, nsee brown part.dendritic powder, nparticles, usually of electrolytic origin, having the typical pine tree structure.densification crack, na defect caused by differential stresses in a region of a part that h
39、as experienced large differences inshrinkage during sintering.density (dry), nsee sintered density.density (wet), nsee impregnated density.density ratio, nthe ratio, often expressed as a percentage, of the density of a porous material to the density of the same materialcompletely free of porosity. S
40、ynonymous with relative density.die, na member of the compacting tool set forming the cavity in which the powder is compacted or a PM compact is repressed.die body, nthe stationary or fixed part of a die.die insert, na removable liner or part of a die body.die set, nthe parts of a press that hold an
41、d locate the die in proper relation to the punches.diffusion-alloyed powder, na partially alloyed powder produced by means of a diffusion anneal.dimensional change of a compact, nthe difference, at room temperature, between the size of the sintered specimen and the diesize.DISCUSSIONThe difference i
42、n dimensions is usually reported as a percentage of the die size. It should include a (+) when the sintered part is larger than the diesize and a () when the sintered part is smaller than the die size.disintegration, nthe reduction of massive material to powder.dispersion-strengthened material, na m
43、aterial consisting of a metal and finely dispersed, substantially insoluble, metallic ornonmetallic phase.dissociated ammonia, na reducing gas produced by the thermal decomposition of anhydrous ammonia over a catalyst, resultingin a gas of 75 % hydrogen and 25 % nitrogen. Synonymous with cracked amm
44、onia.double-action pressing, na method by which a powder is pressed in a die between opposing moving punches.double press-double sinter, nto repress and sinter a previously presintered or sintered compact.DISCUSSIONUsed to describe a four-step manufacturing process.4 There is detailed information on
45、 numerous cracks, their location, cause, and prevention in a handbook published by Metal Powder Industries Federation, Princeton, NewJersey, “The Common Cracks in PM Compacts” by D. Zenger and H. Cai.B243 194ejection crack, na defect that occurs during the removal of the compact from the tooling (us
46、ually occurs in multilevel parts thatare not supported uniformly on all lower surfaces).electrolytic powder, npowder produced by electrolytic deposition or by the pulverization of an electrodeposit.endothermic gas, na reducing gas atmosphere used in sintering, produced by the reaction of a hydrocarb
47、on vapor and air overa catalyst with the use of an external heat source. It is low in carbon dioxide and water vapor while containing combustiblesof about 60 atomic percent hydrogen and carbon monoxide combined.equalizing, nsee blending.exothermic atmosphere (gas), na reducing gas atmosphere used in
48、 sintering, produced by partial or complete combustion ofhydrocarbon fuel gas and air with the associated generation of heat. The maximum combustible content is approximately 25atomic percent.explosive compaction, nhigh-energy consolidation of powders by means of a detonation shock wave.exudation, n
49、the action by which all or a portion of the low melting constituent of a compact is forced to the surface duringsintering. Sometimes referred to as “bleed out.” Synonymous with sweating.feedshoe, na part of the compacting press that delivers powder to the die cavity, usually by sliding an open-bottomed powdercontainer over the open top of the die.f
