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Properties of sintered hypereutectoid PM steels
and cutting applications was reviewed with reference to competition from cemented carbides. The addition of hard particles to PM HSS was investigated and sinterabilities in vacuum and dissociated NHs w e r e compared. Measurements were made of transverse rupture stress, and structures were examined by optical and electron microscopy.
been obtained by the use of HIP. This was attributed to the eli~jna~'~n of ~sidual uninfiltrated pores~ E f f ~ (if ~ n t ~d HIP t e m p e r a t u r e w e r e d e t e r m i n e d . Microstructual modification was related to process conditions and the most significant factors controlling the densification were discussed.
satisfy high performance requirements cost effectively.
Powder characterization POWDER A N D P O R O U S COMPACT MATERIALS CHARACTERIZATION BY ABSORPTION
Novel materials EFFECTS OF GRAPHITE ADDITIONS A N D S I N T E R I N G A T M O S P H E R E S ON D E N S I F I C A T I O N O F CARBONYL IRON POWDERS
K. Hayashi and T-W. [Jim, (University of Tokyo, Japan). The high densification of carbonyl Fe powder with graphite additions, after vacuum and H sintering was investigated. The minimum percentage graphite was reported to be 0.4-0.5% for vacuum and 1.2-1.4% for H sintering. The results were discussed in terms of equilibrium pressure of CO and the presence of AI, Nb, Ti and V.
Secondary operations~high density III II
IIIIBI
COST BENEFIT RELATIONSHIP OF PRESSED AND REPRESSED MATERIALS
T. Haberberger et al, (Alpha Sintered Metals Inc, Ridgeway, USA). A comparison was made between the mechanical properties of pressed and sintered steel parts with those of repressed materials. It was shown that a wide range of properties are enhanced by repressing. A n analysis of additional costs of repressing was presented.
AUSROLLING O F S I N T E R E D S T E E L S FOR B E A R I N G E L E M E N T S
R.~ Queeney et al, (Pennsylvania State University, USA). It was shown that the ausrolling of sintered steel r e d u c e s surface porosity from 15% in the as-sintered material to less than 1% and improves properties. The densification extended to 1.5 mm from the surface and Vickers hardnesses of 800 to 100 were obtained. Rolling contact fatigue testing showed the ausrolled steel to have superior performance. IMPACT S T R E N G T H O F H I P E D COPPER INFILTRATED SINTERED STEEL
S. Pelletier and B. Champagne, (National Research Council of Canada, Canada). It w a s reported that improvements in the densification of Cu infiltrated steel had
Jl J II
PROCESSING AND PROPERTIES OF A TUNGSTEN-TITANIUM ALLOY
C. Bagnall and D. Kapoor, (Westinghouse Electric Corp, Beaver, USA). The ballistic performances of W heavy alloys (WHA) and depleted U (DU) were compared. DU was said to be superior even though the properties of WHA have been improved. The reasons for t h e b e t t e r performance of DU, adiabatic shear during armour penetration and retention of a s h a r p p r o f i l e , w e r e e x p l a i n e d . The properties of ballistic test samples, made from W and Ti powders by extrusion and HIP, were investigated. Ti replaced Ni and Fe in the heavy alloy matrix as it has the p r o p e r t i e s r e q u i r e d to p r o d u c e t h e a d i a b a t i c s h e a r n e e d e d for good p e n e t r a t i o n of a r m o u r . R e s u l t s of compression tests at high and low strain rates, fractographic and metallographic studies were presented.
P R E P A R A T I O N O F URANIUMZIRCONIUM ALLOY N U C ~ FUEL E L E M E N T S BY PM
A.A. Solomon and S.M. McDeavitt, (Purdue University, USA). U-10%Zr alloys for reactor fuel element applications were produced in two ways, by vacuum reduction of U and Zr hydrides and from elemental powder mixtures. Sintering of the hydride materials required high temperatures and there was conversion of Zr into another phase containing C, N and O. The elemental powder specimens gave relatively pure materials with a density o f 92%. HIP of these alloys was described.
L-M. Berger, (Fraunhofer Inst for Ceramic Engineering, Dresden, Germany). Measurement of full absorption isotherm of p o w d e r s with m o d e r n instruments was described and the information which can be determined was outlined. Specific surface, data concerning micropores (less than 1.6 n m ) and mesopores (1.6 to 300 nm) and pore distribution can be found and the importance of these was discussed. The theoretical background was outlined.
QUANTIFICATION OF PARTICLE SHAPE IN A BATCH O F POWDER
B.C. Mann and LJ. Cuddy, (Pennsylvania State University, USA). It was pointed out that whereas particle size and size distribution in a batch is a quantitative m e a s u r e of p o w d e r characteristics, particle shape is only expressed qualitatively. The use of Fourrier analysis to assess particle shape was proposed. A particle shape is scanned and a polygon which approximates to the particle shape is deduced. The arc length and angular bend of each segment is measured and the data is used to create a Fourrier series representing the particle shape. The coefficients in the series are averaged over a large number of particles 'in the sample and a Fourrier signature graph is constructed. From this the complexity of the particle shape, the variability of shape in the sample and overlaps of standard deviations give measure of similarity between lots. Examples of the use of the method for widely differing samples were described and discussed.
Ferrous base I
DISCONTINUOUSLY REINFORCED A L U M I N I U M ALLOYS MADE BY PM
W.H. Hunt et al, (Alcoa I N N O M E T A L X , Rockdale, USA). Discontinuously reinforced Al alloys were discussed with reference to the use of P M processes for production. P M methods allow selection of a wide range of matrix and reinforcement materials and give uniformity of structure and properties f o r a v a r i e t y o f a p p l i c a t i o n s . An introduction to PM processing methods used was given and a case study approach was used to show how these materials can
LIQUID DYNAMIC C O M P A C T I O N FOR PRODUCTION OF SAE1008 STEEL WITH A D D I T I O N S O F A L U M I N I U M A N D NITROGEN
N~I. Grant et al, (Massachusetts Inst of Technology, USA). An SAE1008 steel with additions of 0.- wt% N and 0.1376 Al was spray deposited and fully densified by hot rolling by 70% at 1000 to 1100°C. The as-deposited steel was 95% dense and after rolling the grain size was 4 pJn because of the effects of dynamic recrystallization and precipitation of AlN.
MPR November 1992 55
been obtained by the use of HIP. This was attributed to the eli~jna~'~n of ~sidual uninfiltrated pores~ E f f ~ (if ~ n t ~d HIP t e m p e r a t u r e w e r e d e t e r m i n e d . Microstructual modification was related to process conditions and the most significant factors controlling the densification were discussed.
satisfy high performance requirements cost effectively.
Powder characterization POWDER A N D P O R O U S COMPACT MATERIALS CHARACTERIZATION BY ABSORPTION
Novel materials EFFECTS OF GRAPHITE ADDITIONS A N D S I N T E R I N G A T M O S P H E R E S ON D E N S I F I C A T I O N O F CARBONYL IRON POWDERS
K. Hayashi and T-W. [Jim, (University of Tokyo, Japan). The high densification of carbonyl Fe powder with graphite additions, after vacuum and H sintering was investigated. The minimum percentage graphite was reported to be 0.4-0.5% for vacuum and 1.2-1.4% for H sintering. The results were discussed in terms of equilibrium pressure of CO and the presence of AI, Nb, Ti and V.
Secondary operations~high density III II
IIIIBI
COST BENEFIT RELATIONSHIP OF PRESSED AND REPRESSED MATERIALS
T. Haberberger et al, (Alpha Sintered Metals Inc, Ridgeway, USA). A comparison was made between the mechanical properties of pressed and sintered steel parts with those of repressed materials. It was shown that a wide range of properties are enhanced by repressing. A n analysis of additional costs of repressing was presented.
AUSROLLING O F S I N T E R E D S T E E L S FOR B E A R I N G E L E M E N T S
R.~ Queeney et al, (Pennsylvania State University, USA). It was shown that the ausrolling of sintered steel r e d u c e s surface porosity from 15% in the as-sintered material to less than 1% and improves properties. The densification extended to 1.5 mm from the surface and Vickers hardnesses of 800 to 100 were obtained. Rolling contact fatigue testing showed the ausrolled steel to have superior performance. IMPACT S T R E N G T H O F H I P E D COPPER INFILTRATED SINTERED STEEL
S. Pelletier and B. Champagne, (National Research Council of Canada, Canada). It w a s reported that improvements in the densification of Cu infiltrated steel had
Jl J II
PROCESSING AND PROPERTIES OF A TUNGSTEN-TITANIUM ALLOY
C. Bagnall and D. Kapoor, (Westinghouse Electric Corp, Beaver, USA). The ballistic performances of W heavy alloys (WHA) and depleted U (DU) were compared. DU was said to be superior even though the properties of WHA have been improved. The reasons for t h e b e t t e r performance of DU, adiabatic shear during armour penetration and retention of a s h a r p p r o f i l e , w e r e e x p l a i n e d . The properties of ballistic test samples, made from W and Ti powders by extrusion and HIP, were investigated. Ti replaced Ni and Fe in the heavy alloy matrix as it has the p r o p e r t i e s r e q u i r e d to p r o d u c e t h e a d i a b a t i c s h e a r n e e d e d for good p e n e t r a t i o n of a r m o u r . R e s u l t s of compression tests at high and low strain rates, fractographic and metallographic studies were presented.
P R E P A R A T I O N O F URANIUMZIRCONIUM ALLOY N U C ~ FUEL E L E M E N T S BY PM
A.A. Solomon and S.M. McDeavitt, (Purdue University, USA). U-10%Zr alloys for reactor fuel element applications were produced in two ways, by vacuum reduction of U and Zr hydrides and from elemental powder mixtures. Sintering of the hydride materials required high temperatures and there was conversion of Zr into another phase containing C, N and O. The elemental powder specimens gave relatively pure materials with a density o f 92%. HIP of these alloys was described.
L-M. Berger, (Fraunhofer Inst for Ceramic Engineering, Dresden, Germany). Measurement of full absorption isotherm of p o w d e r s with m o d e r n instruments was described and the information which can be determined was outlined. Specific surface, data concerning micropores (less than 1.6 n m ) and mesopores (1.6 to 300 nm) and pore distribution can be found and the importance of these was discussed. The theoretical background was outlined.
QUANTIFICATION OF PARTICLE SHAPE IN A BATCH O F POWDER
B.C. Mann and LJ. Cuddy, (Pennsylvania State University, USA). It was pointed out that whereas particle size and size distribution in a batch is a quantitative m e a s u r e of p o w d e r characteristics, particle shape is only expressed qualitatively. The use of Fourrier analysis to assess particle shape was proposed. A particle shape is scanned and a polygon which approximates to the particle shape is deduced. The arc length and angular bend of each segment is measured and the data is used to create a Fourrier series representing the particle shape. The coefficients in the series are averaged over a large number of particles 'in the sample and a Fourrier signature graph is constructed. From this the complexity of the particle shape, the variability of shape in the sample and overlaps of standard deviations give measure of similarity between lots. Examples of the use of the method for widely differing samples were described and discussed.
Ferrous base I
DISCONTINUOUSLY REINFORCED A L U M I N I U M ALLOYS MADE BY PM
W.H. Hunt et al, (Alcoa I N N O M E T A L X , Rockdale, USA). Discontinuously reinforced Al alloys were discussed with reference to the use of P M processes for production. P M methods allow selection of a wide range of matrix and reinforcement materials and give uniformity of structure and properties f o r a v a r i e t y o f a p p l i c a t i o n s . An introduction to PM processing methods used was given and a case study approach was used to show how these materials can
LIQUID DYNAMIC C O M P A C T I O N FOR PRODUCTION OF SAE1008 STEEL WITH A D D I T I O N S O F A L U M I N I U M A N D NITROGEN
N~I. Grant et al, (Massachusetts Inst of Technology, USA). An SAE1008 steel with additions of 0.- wt% N and 0.1376 Al was spray deposited and fully densified by hot rolling by 70% at 1000 to 1100°C. The as-deposited steel was 95% dense and after rolling the grain size was 4 pJn because of the effects of dynamic recrystallization and precipitation of AlN.
MPR November 1992 55