Accession Number : ADD014030

Title :   Billet Conditioning Technique for Manufacturing Powder Metallurgy Preforms.

Descriptive Note : Patent, Filed 6 Jul 87, patented 9 Aug 88,

Corporate Author : DEPARTMENT OF THE AIR FORCE WASHINGTON DC

Personal Author(s) : Gegel, Harold L ; Prasad, Yellapregada V ; Doraivelu, Sokka M ; Srinivasan, Raghavan ; Gunasekera, J S

Report Date : 09 Aug 1988

Pagination or Media Count : 24

Abstract : Described is a process for manufacturing powder metallurgy (P/M) performs which are conditioned for optimum intrinsic workability is described which comprises steps of heating a quantity of P/M material in a can to a first preselected temperature under vacuum to degas the material, compacting the canned material at a second preselected temperature under pressure to provide a compact of the material; or cold compacting the powder to about 75% density and degassing it at suitable temperature and then vacuum hot pressing the powder at about 0.75 melting point; generating flow stress data as a function of strain rate and temperature on samples of the compact at predetermined strain within predetermined ranges of temperature and strain rate and determining powder dissipation efficiency of the compact and entropy rate ratio within those ranges of temperature and strain rate; selecting values of stain rate and extrusion temperature at which dynamic recrystallization is the dominant metallurgical mechanism characterizing the compact: and extruding the compact in an extrusion can at the selected extrusion temperature and at an extrusion rate corresponding to the selected strain rate using a streamlined die. An improved processing map for preselecting optimum processing parameters for the material is described. Keywords: Patents. (kt)

Descriptors :   *PATENTS, *POWDER METALLURGY, *BILLETS(MATERIALS), COMPACTING, DISCOLORATION, DISSIPATION, DYNAMICS, EFFICIENCY, ENTROPY, EXTRUSION, FLOW, HOT PRESSING, LOW TEMPERATURE, MANUFACTURING, MAPS, MATERIALS, OPTIMIZATION, PARAMETERS, POWDER METALS, PROCESSING, RANGE(EXTREMES), RATES, RATIOS, RECRYSTALLIZATION, SAMPLING, STRAIN RATE, STRESSES, TEMPERATURE, VACUUM, VALUE

Subject Categories : Fabrication Metallurgy
      Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE