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Effect of vanadium on tensile strength of chromium-molybdenum PM steels
Powder production TITANL4 POWDER SYNTHESISBY HYDROLYSIS OF TITANIUM ISOPROPOXIDE K.M.S.Khalil, M.I.Zaki. (Kuwait University, Kuwait.) Powder Technol., Vol92, No 3, 1997,233-239. A study of production of TiO, powders with high surface areas, by calcination at 400°C of precursors formed by hydrolysis of Ti isopropoxide, is described. The TiO, comprises anatase crystallites irrespective of precursor but there was variation in surface texture. Production conditions for TiO, powders of higher surface area are resolved.
Pressing EFFECT OF CYCLIC PRESSURE ON CONSOLIDATION OF COMPOSITE POWDER SYSTEMS C.Y.Huang, G.S.Daehn. (Ohio State University, Columbus, USA.) Acta Mater., Vol45, No 10, 1997, 4283-4296. Effects of cyclic pressure on ambient temperature consolidation of composite powders were investigated. Pb-TiO,, PbSic, Al-Al,O, and Zn-Al,Os, each with 40~01% ceramic, were used. Cyclic and static pressing are compared. Cyclic pressures are reported to enhance densification. This is attributed to pressure changes inducing plastic deformation due to mis-match of elastic strains between metal and ceramic. The significance is discussed. OPTIMIZATION OF FORM AND DIMENSION OF POROUS POWDER PARTS O.P.Reut et al. Poroshkovaya Metall., No 11112, 1996,80-84. (In Russian.) Optimization of shape and size of porous PM parts is discussed with reference to manufacture and productivity. The optimization process is described and a computer program is realized for parts with ribbed surfaces.
Sintering SUPERSOLIDUS LIQUID PIIASE SINTERING OF PREALLOYED POWDERS R.M.German. (Pennsylvania State University, Pennsylvania, USA.) MetaEZ. Mater. Trans. A, Vol 28, No 7, 1997, 1553-1567.
36 MPR May 1998
A model for densification of prealloyed powders, which form liquids at supersolidus temperatures, is presented. The model considers powder characteristics and process conditions. The liquid forms and spreads to form an interparticle capillary bond which induces densitication. The alloy passes through a ‘mushy’ stage as a result of grain boundary wetting. Viscous flow is considered to be the densification mechanism. Predicted and experimental data are compared and agreement is reported. The model was tested against a range of steels, two Ni alloys and a bronze.
Fundamentals SIMULATION OF PACKED BEDS OF MONO-SIZED SPHERES IN CYLINDRICAL CONTAINERS G.E.Mueller. (University of Missouri, Rolla, USA.) Powder Technol.,Vol92, No 2, 1997, 179-183. Packing of mono-sized spheres in cylinders was investigated. The packed beds were prepared so that each sphere was stable, touching three other spheres or two spheres and the container wall. The packing procedures were determined by models. Overall and radial void fractions were calculated and compared with experimental data. MODELLING OF PACKING OF FINE PARTICLES J.Bridgewater et al. (University of Cambridge, Cambridge, UK.) Powder Technol.,Vol90, No 3, 1997, 185194. A model for packing of fine particles is discussed. It is suggested that initial porosity and packing size ratio are factors that require consideration. The model is tested against standard poured and tapped fused Al,O, powders. The results show that simple measurements can lead to formulation of equations to quantify initial characteristics.
Chromium MECIIANICAL PROPERTIES OF WEAR-RESISTANTHETEROGENEOUS CBROMIUM BASE MATERIALS L.N.Orlova et al. Poroshkovuya MetalE., No 11/12, 1996, 61-67. (In Russian.) Processing, structure and properties of materials fabricated from Fe, Cr and Cr,C, powders were investigated. It is
reported that alloys with good mechanical and corrosion properties had been produced.
Iron and steel EFFECT OF VANADIUM ON TENSILE STRENGTH OF CIIROMIUMMOLYBDENUM PM STEELS S.Unami et al. (University of Tokyo, Tokyo, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 9, 1996, 1106-1110. (In Japanese.) It is reported that a lwt%Cr0.3%Mo-0.3%V prealloyed steel powder, without Mn, for high strength parts, had been prepared. V increased strength compared with the Cr-Mo steel. V is considered to reduce hardenability. Higher strength is attributed to V carbonitrides. REDUCTION IN SINTERING YEMPERATIJREOF STAINLESS STEEL BY ADDITION OF SILICON AND BORON M.Nakamura et aE. (Iwate University, Morioka, Japan.) J. Jpn. Sot. Powder Powder MetalL, Vol 43, No 9, 1996, 1111-1116. (In Japanese.) A study of Si and B in reducing the temperature for liquid phase sintering of 304L stainless steel is described. The sintering temperature was 1225°C. A duplex structure is developed by the Si and increased strength is attributed to crystallites of ferrite in the austenite. B improved ductility by precipitation of fine boride particles. A tensile strength of 600 MPa with 37% elongation but no improvement in corrosion are reported. EFFECT OF INCLUSIONS ON MECI-IANICALBEIIAVIOUR OF STAINLESS STEEL AT ELEVATED TEMPERATURES T.Isomoto, H.Nagai. (Osaka University, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 9, 1996, 1147-1152. (In English.) An investigation of hot extruded PM 304L stainless steel, with varying oxide inclusions is reported. Tensile and creep at elevated temperatures were studied. Oxide inclusions were formed by additions of Al, Si, Cr-Mn or Cr. Al oxides reduced ductility above 800°C even at low 0 contents. Al and Si oxides were more detrimental to properties than Cr or Cr-Mn oxides.
Pressing EFFECT OF CYCLIC PRESSURE ON CONSOLIDATION OF COMPOSITE POWDER SYSTEMS C.Y.Huang, G.S.Daehn. (Ohio State University, Columbus, USA.) Acta Mater., Vol45, No 10, 1997, 4283-4296. Effects of cyclic pressure on ambient temperature consolidation of composite powders were investigated. Pb-TiO,, PbSic, Al-Al,O, and Zn-Al,Os, each with 40~01% ceramic, were used. Cyclic and static pressing are compared. Cyclic pressures are reported to enhance densification. This is attributed to pressure changes inducing plastic deformation due to mis-match of elastic strains between metal and ceramic. The significance is discussed. OPTIMIZATION OF FORM AND DIMENSION OF POROUS POWDER PARTS O.P.Reut et al. Poroshkovaya Metall., No 11112, 1996,80-84. (In Russian.) Optimization of shape and size of porous PM parts is discussed with reference to manufacture and productivity. The optimization process is described and a computer program is realized for parts with ribbed surfaces.
Sintering SUPERSOLIDUS LIQUID PIIASE SINTERING OF PREALLOYED POWDERS R.M.German. (Pennsylvania State University, Pennsylvania, USA.) MetaEZ. Mater. Trans. A, Vol 28, No 7, 1997, 1553-1567.
36 MPR May 1998
A model for densification of prealloyed powders, which form liquids at supersolidus temperatures, is presented. The model considers powder characteristics and process conditions. The liquid forms and spreads to form an interparticle capillary bond which induces densitication. The alloy passes through a ‘mushy’ stage as a result of grain boundary wetting. Viscous flow is considered to be the densification mechanism. Predicted and experimental data are compared and agreement is reported. The model was tested against a range of steels, two Ni alloys and a bronze.
Fundamentals SIMULATION OF PACKED BEDS OF MONO-SIZED SPHERES IN CYLINDRICAL CONTAINERS G.E.Mueller. (University of Missouri, Rolla, USA.) Powder Technol.,Vol92, No 2, 1997, 179-183. Packing of mono-sized spheres in cylinders was investigated. The packed beds were prepared so that each sphere was stable, touching three other spheres or two spheres and the container wall. The packing procedures were determined by models. Overall and radial void fractions were calculated and compared with experimental data. MODELLING OF PACKING OF FINE PARTICLES J.Bridgewater et al. (University of Cambridge, Cambridge, UK.) Powder Technol.,Vol90, No 3, 1997, 185194. A model for packing of fine particles is discussed. It is suggested that initial porosity and packing size ratio are factors that require consideration. The model is tested against standard poured and tapped fused Al,O, powders. The results show that simple measurements can lead to formulation of equations to quantify initial characteristics.
Chromium MECIIANICAL PROPERTIES OF WEAR-RESISTANTHETEROGENEOUS CBROMIUM BASE MATERIALS L.N.Orlova et al. Poroshkovuya MetalE., No 11/12, 1996, 61-67. (In Russian.) Processing, structure and properties of materials fabricated from Fe, Cr and Cr,C, powders were investigated. It is
reported that alloys with good mechanical and corrosion properties had been produced.
Iron and steel EFFECT OF VANADIUM ON TENSILE STRENGTH OF CIIROMIUMMOLYBDENUM PM STEELS S.Unami et al. (University of Tokyo, Tokyo, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 9, 1996, 1106-1110. (In Japanese.) It is reported that a lwt%Cr0.3%Mo-0.3%V prealloyed steel powder, without Mn, for high strength parts, had been prepared. V increased strength compared with the Cr-Mo steel. V is considered to reduce hardenability. Higher strength is attributed to V carbonitrides. REDUCTION IN SINTERING YEMPERATIJREOF STAINLESS STEEL BY ADDITION OF SILICON AND BORON M.Nakamura et aE. (Iwate University, Morioka, Japan.) J. Jpn. Sot. Powder Powder MetalL, Vol 43, No 9, 1996, 1111-1116. (In Japanese.) A study of Si and B in reducing the temperature for liquid phase sintering of 304L stainless steel is described. The sintering temperature was 1225°C. A duplex structure is developed by the Si and increased strength is attributed to crystallites of ferrite in the austenite. B improved ductility by precipitation of fine boride particles. A tensile strength of 600 MPa with 37% elongation but no improvement in corrosion are reported. EFFECT OF INCLUSIONS ON MECI-IANICALBEIIAVIOUR OF STAINLESS STEEL AT ELEVATED TEMPERATURES T.Isomoto, H.Nagai. (Osaka University, Osaka, Japan.) J. Jpn. Sot. Powder Powder Metall., Vol 43, No 9, 1996, 1147-1152. (In English.) An investigation of hot extruded PM 304L stainless steel, with varying oxide inclusions is reported. Tensile and creep at elevated temperatures were studied. Oxide inclusions were formed by additions of Al, Si, Cr-Mn or Cr. Al oxides reduced ductility above 800°C even at low 0 contents. Al and Si oxides were more detrimental to properties than Cr or Cr-Mn oxides.