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Mechanics of metal powder forming — An international research programme
requires a finite number of stress reversals at a given point. Part wear alters the stress distribution and pitting may not occur. An investigation was described in which laws of cumulative damage and wear intensity maps were determined for a 1.75%Ni1.5XCu-O.%Mo-0.5%C steel. FRETTING LOW ALLOY
BEHAVIOUR STEELS
OF
SINTERED
B.Martin et al. (Ecole Centrale de Lyon, Lyon, France.) It was reported that Running Condition Fretting Maps and Materials Response Fretting Maps had been compiled from data from investigations of fretting behaviour of a range of low alloy steels. Cracking and particle detachment were used as guides to wear resistance and contact fatigue properties depending on test conditions. WEAR AND CRACKING OF SINTERED HIGH SPEED STEEL MATRIX COMPOSITES IN FRETTING CONDITIONS A.Wronski et al. (University of Bradford, Yorkshire, UK) Failure of automotive parts, rocker arms and valves, due to wear and cracking, was discussed. It was reported that such damage can be reproduced in fretting tests. The method was applied to high speed steels with additions of MnS, as a lubricant, and extra TIC, which was shown to confer improved wear resistance.
Process AUTOMATED EVALUATION INSPECTION
instrumentation NON-DESTRUCTIVE SYSTEM FOR OF PM COMPONENTS
J.L.Walker, G.L.Workman (University of Alabama, Huntsville, USA) A flaw detection system which uses a neural network and statistical analysis to resolve variations in ultrasonic stress wave factors resulting from part variations was described. The method was evaluated on specimens with a range of defect sizes and geometries. Accept/reject criteria were established. DC POTENTIAL DETECTION TO UNIAXIAL
OF
DROP FOR DEFECTS COMPACTION
RELATED
B.A.van den Bos (Linkoping University, Sweden.) It was reported that a direct current potential drop technique shows promise in non-destructive detection of defects, such as cracks, density variations and surface decarburization, in PM parts but is tedius due to the small volume tested. A finite element method was used in a test program to reduce testing time. Examples were given.
40
MPR
November
1996
USE OF IMPROVED
RESONANT INSPECTION POWDERED METAL
FOR PARTS
R.H.Nath et al. (Quatrosonics Inc., USA.) A technique which uses a PM part’s vibrational resonances to non-destructively reveal defects was described. Other NDT methods scan for the defect but resonant inspection scans the whole part for changes in structural integrity and is faster. The technique can be automated and allows 100% inspection at low cost. Parts are not rejected by subjective judgements. The technique is based on ultrasonic resonance spectroscopy.
High
performance
SUPERSOLIDUS BRAZING USING BASE POWDERS
alloys
SINTERING PREALLOYED
AND NICKEL
R.M.German et al. (Pennsylvania State University, University Park, USA.) Effects of process conditions on sintering of low melting point prealloyed Ni base powders, used in brazing were investigated. Electron probe microanalysis was used to determine densification mechanisms and the role of alloy elements. LOW CYCLE SUPERALLOY
FATIGUE REPAIR
PROPERTIES JOINTS
OF
J.Liburdi et al. (Liburdi Engineering Ltd., Canada.) It was reported that simulated repair joints in Inconel 738 had been subjected to fatigue tests. The joints were made by supersolidus liquid phase sintering of superalloy powder of the same composition as the base metal. The structure of the repair was a cast base metal with a PM overlay. Effects of pore size and location were studied and comparison made between repaired and cast materials. PROPERTIES SINTERED
OF HIGH DENSITY 316L STAINLESS STEEL
J.Wood et al. (University of Nottingham, Nottingham, UK.) Carburizing of ferrous parts to improve wear resistance was discussed. It was noted that liquid carburizing is unsuitable for PM parts and that gas carburizing is better than pack. Studies of the effects of alloy elements on ion nitriding and nitrocarburizing were refered to. The investigation described was to determine the viability of low pressure and plasma carburizing on C free steels. Structure and properties were described.
Modelling MECHANICS FORMING RESEARCH
OF METAL POWDER - AN INTERNATIONAL PROGRAMME
D.Bouvard et al. (Inst. National Polytechnique de Grenoble, Grenoble, France.)
It was reported that an international program studying the modelling of hot and cold compaction of metal powders had been instituted involving 30 institutions in 15 countries. Phases of the study are mechanical behaviour of powder, modelling of collated data, compaction of a part and simulation of compaction and comparison with a real part. Attention is given to HIP. Experimental devices are being developed. Examples of data for stainless steel were given. Proceedure for identification of parameters in constitutive equations was discussed. The part used for validation was described. DIRECT SIMULATION COMPACTION AND OF STEEL POWDER ANALYSIS
OF CONSOLIDATION BY EULERIAN
JKihara et al. (University of Tokyo,Tokyo, Japan.) Granular modelling was discussed with regard to quantitative description of powder flow and consolidation in mixing. At densities above 75 to 80% continuum mechanics models must be used for compaction analysis. Factors omitted, fine pore structure and locallized physical properties, are noted. It was reported that powder assemblies had been modelled by eulerian finite element methods which incorporate elasto-plastic deformation and stress transfer. Experimental load/ displacement data was compared with calculated results. Micro-mechanics were used to deduce elasto-plastic relationships. MACRO-MICRO MODELLING VISCOUS SINTERING AND ISOSTATIC PRESSING
FOR HOT
JKihara et al. (University of Tokyo,Tokyo, Japan.) Drwabacks in finite element and difference methods for modelling shrinkage in sintering and HIP were discussed. It was noted that granular modelling and microscopic flow analysis do not account for dimensional change. It was reported that macroand micromodelling can link the two techniques and allows prediction of shrinkage and locallised sintering. The elasto-creep frame was used to trace dependence of shrinkage with time. The models were illustrated by numerical examples.
Aluminium RESEARCH SINTERING TRANSITION
sintering IN LIQUID PHASE OF ALUMINIUMMETAL SYSTEM
G.N.Romanov, N.S.Timofeev (Yakut Univer sity, Russia.) A theory of LPS in interacting systems was discussed with respect to solid and liquid phase diffusion. Four classes of system were identified. Studies of Al transition metal systems were described. The possibility of producing porous and dense materials in one system was demonstrated.
BEHAVIOUR STEELS
OF
SINTERED
B.Martin et al. (Ecole Centrale de Lyon, Lyon, France.) It was reported that Running Condition Fretting Maps and Materials Response Fretting Maps had been compiled from data from investigations of fretting behaviour of a range of low alloy steels. Cracking and particle detachment were used as guides to wear resistance and contact fatigue properties depending on test conditions. WEAR AND CRACKING OF SINTERED HIGH SPEED STEEL MATRIX COMPOSITES IN FRETTING CONDITIONS A.Wronski et al. (University of Bradford, Yorkshire, UK) Failure of automotive parts, rocker arms and valves, due to wear and cracking, was discussed. It was reported that such damage can be reproduced in fretting tests. The method was applied to high speed steels with additions of MnS, as a lubricant, and extra TIC, which was shown to confer improved wear resistance.
Process AUTOMATED EVALUATION INSPECTION
instrumentation NON-DESTRUCTIVE SYSTEM FOR OF PM COMPONENTS
J.L.Walker, G.L.Workman (University of Alabama, Huntsville, USA) A flaw detection system which uses a neural network and statistical analysis to resolve variations in ultrasonic stress wave factors resulting from part variations was described. The method was evaluated on specimens with a range of defect sizes and geometries. Accept/reject criteria were established. DC POTENTIAL DETECTION TO UNIAXIAL
OF
DROP FOR DEFECTS COMPACTION
RELATED
B.A.van den Bos (Linkoping University, Sweden.) It was reported that a direct current potential drop technique shows promise in non-destructive detection of defects, such as cracks, density variations and surface decarburization, in PM parts but is tedius due to the small volume tested. A finite element method was used in a test program to reduce testing time. Examples were given.
40
MPR
November
1996
USE OF IMPROVED
RESONANT INSPECTION POWDERED METAL
FOR PARTS
R.H.Nath et al. (Quatrosonics Inc., USA.) A technique which uses a PM part’s vibrational resonances to non-destructively reveal defects was described. Other NDT methods scan for the defect but resonant inspection scans the whole part for changes in structural integrity and is faster. The technique can be automated and allows 100% inspection at low cost. Parts are not rejected by subjective judgements. The technique is based on ultrasonic resonance spectroscopy.
High
performance
SUPERSOLIDUS BRAZING USING BASE POWDERS
alloys
SINTERING PREALLOYED
AND NICKEL
R.M.German et al. (Pennsylvania State University, University Park, USA.) Effects of process conditions on sintering of low melting point prealloyed Ni base powders, used in brazing were investigated. Electron probe microanalysis was used to determine densification mechanisms and the role of alloy elements. LOW CYCLE SUPERALLOY
FATIGUE REPAIR
PROPERTIES JOINTS
OF
J.Liburdi et al. (Liburdi Engineering Ltd., Canada.) It was reported that simulated repair joints in Inconel 738 had been subjected to fatigue tests. The joints were made by supersolidus liquid phase sintering of superalloy powder of the same composition as the base metal. The structure of the repair was a cast base metal with a PM overlay. Effects of pore size and location were studied and comparison made between repaired and cast materials. PROPERTIES SINTERED
OF HIGH DENSITY 316L STAINLESS STEEL
J.Wood et al. (University of Nottingham, Nottingham, UK.) Carburizing of ferrous parts to improve wear resistance was discussed. It was noted that liquid carburizing is unsuitable for PM parts and that gas carburizing is better than pack. Studies of the effects of alloy elements on ion nitriding and nitrocarburizing were refered to. The investigation described was to determine the viability of low pressure and plasma carburizing on C free steels. Structure and properties were described.
Modelling MECHANICS FORMING RESEARCH
OF METAL POWDER - AN INTERNATIONAL PROGRAMME
D.Bouvard et al. (Inst. National Polytechnique de Grenoble, Grenoble, France.)
It was reported that an international program studying the modelling of hot and cold compaction of metal powders had been instituted involving 30 institutions in 15 countries. Phases of the study are mechanical behaviour of powder, modelling of collated data, compaction of a part and simulation of compaction and comparison with a real part. Attention is given to HIP. Experimental devices are being developed. Examples of data for stainless steel were given. Proceedure for identification of parameters in constitutive equations was discussed. The part used for validation was described. DIRECT SIMULATION COMPACTION AND OF STEEL POWDER ANALYSIS
OF CONSOLIDATION BY EULERIAN
JKihara et al. (University of Tokyo,Tokyo, Japan.) Granular modelling was discussed with regard to quantitative description of powder flow and consolidation in mixing. At densities above 75 to 80% continuum mechanics models must be used for compaction analysis. Factors omitted, fine pore structure and locallized physical properties, are noted. It was reported that powder assemblies had been modelled by eulerian finite element methods which incorporate elasto-plastic deformation and stress transfer. Experimental load/ displacement data was compared with calculated results. Micro-mechanics were used to deduce elasto-plastic relationships. MACRO-MICRO MODELLING VISCOUS SINTERING AND ISOSTATIC PRESSING
FOR HOT
JKihara et al. (University of Tokyo,Tokyo, Japan.) Drwabacks in finite element and difference methods for modelling shrinkage in sintering and HIP were discussed. It was noted that granular modelling and microscopic flow analysis do not account for dimensional change. It was reported that macroand micromodelling can link the two techniques and allows prediction of shrinkage and locallised sintering. The elasto-creep frame was used to trace dependence of shrinkage with time. The models were illustrated by numerical examples.
Aluminium RESEARCH SINTERING TRANSITION
sintering IN LIQUID PHASE OF ALUMINIUMMETAL SYSTEM
G.N.Romanov, N.S.Timofeev (Yakut Univer sity, Russia.) A theory of LPS in interacting systems was discussed with respect to solid and liquid phase diffusion. Four classes of system were identified. Studies of Al transition metal systems were described. The possibility of producing porous and dense materials in one system was demonstrated.