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Martensitic transformations in titanium-nickel-copper shape memory alloys
USE OF ORGANIC BINDERS IN POWDER MIXTUBES FOR IMPROVEMENT OF DIMENSIONAL STABILITY
T.de Carvalho et al. (Belgo Brasiliera Ltda, Sao Paulo, Brazil.) The need to control process variables in order to attain dimensional stability of sintered steels was emphasized. It was reported that the use of an organic binder, in the powder mixture, was effective in minimizing segregation. The effects of organic binders on dimensional stability of compacted and sintered steels were evaluated.
Hard materials MICROSTRUCTURAL EVOLUTION CEMENTED CARBIDES DURING SINTERING
IN
O.Lavergne et al. (CERMeP, Grenoble, France.) Microstructural development, during liquid phase sintering of cemented carbides, was discussed with reference to normal and abnormal grain growth, inhibition by additives and measurements to quantify structural evolution. It was shown that the initial size of WC grains and matrix composition are the main factors in structural evolution and that these effects are still observed in the presence of grain growth inhibitors. TRE BORDERLINE BETWEEN CERMET AND BARDMETAL
T.Viatte et al. (Teledyne Metalworking Products, LaVergne, USA.) Studies of materials containing different proportions of Ti(C,N) and WC, with a Co binder and MO& as grain growth inhibitor, were described. It is reported that if Ti(C,N) is dominant in the hardmetal skeleton the structure is cubic and hexagonal if WC predominates. These accept plastic deformation differently and control high temperature mechanical properties. Some samples had very fine structures with high contiguity, high hardness and good high temperature mechanical properties. PHASE COMPOSITION AND CUTTING PROPERTIES OF CEMENTED CARBIDE TOOL INSERTS
E.Dudkin et al. (Volgograd State University, Volgograd, Technical Russia.) Correlation between composition of cutting tools, cutting performance and thermo-electromotive force (EMF) was discussed. Measurements of thermoEMF were used in a study of phase composition during a cutting operation as an alternative to measurement of temperature. Use of the method to control cutting operations was recommended.
WEAR OF TITANIUM BARDMETALS
CARBIDE
BASE
et al. (Tallinn Technical University, Tallinn, Estonia.) Adhesive and abrasive-erosive wear mechanisms for WC and TiC base materials were compared experimentally. It was concluded that abrasive-erosive wear resistance depends on rigidity of the material, for which WC materials were better than TiC alloys. Adhesive wear resistance was more structure sensitive than for abrasive-erosive wear, being related to the properties and composition of the matrix in respect of plastic deformation. TIC bonded with high strength steel was comparable with WC materials for adhesive wear. J.Kubarsepp
PM2TEC’99. The Abstracts that follow are of papers presented at the 1999 International Conference on Powder which was held in Vancouver,
et al. (OMG Americas, USA.) Use of PM stainless steel in automotive exhaust systems was discussed. It was noted that additions of Ni improve corrosion and thermal fatigue properties. Data on thermal fatigue resistance and corrosion properties of Ni modified PM 400 series stainless steels were presented. P.K.Samal
OF PM
et al. (Pennsylvania State University, USA.) Applications of stainless steels in automotive applications were discussed with regard to the need to develop design and analysis techniques to generate materials capable of withstanding severe service conditions. An investigation of creep properties of materials at 677°C was undertaken, with and without pre-corrosion of samples. Low steady state creep rates were found for 304L and 434L steels, although these behaved differently at fracture. Precorrosion had no noticeable effect. The study was said to indicate the suitability of stainless steel for automotive applications.
A.E.Segall
OF MACHINING
PM STAINLESS
R.J.Causton et al. (Hoeganaes Corp, Riverton, USA.) Improvements in compressibility, green and sintered mechanical properties of high performance sintered stainless steels were reviewed with examples of ferritic and austenitic powders which give such improvements. Consideration was given to automotive applications. EVALUATION OF FACTORS AFFECTING DIMENSIONAL CIIANGE DURING SINTERING OF PM STAINLESS STEELS
IMPROVEMENT IN MECRANICAL PROPERTIES OF PM STAINLESS STEEL BY NICKEL ADDITIONS
EFFECTS
HIGH PERFORMANCE STEELS
Canada,
Stainless steel
CREEP AND CORROSION STAINLESS STEELS
It was noted that stainless steels, except 304L, have poor machinability due to rapid work hardening and that MnS or MoS, may be added to enhance machinability, which may also be affected by sintering atmosphere. Effects of additions of MnS and MoS, on machinability, corrosion and mechanical properties of 316L stainless steel, sintered in H or dissociated ammonia were investigated and the results were discussed.
ADDITIVES
ON CORROSION AND MECRANICAL PROPERTIES OF STAINLESS STEEL
J.B.Terell, P.K.Samal. (OMG Americas, USA.)
J.H.Reinshafgen, G.D.Flick, (Ametek, USA.) Factors influencing dimensional changes during sintering of stainless steel were reviewed with regard to the need to understand these factors. Some of these factors were discussed, as quantitatively as possible, with consideration of inter-relationships.
Shape memory alloys TIT--NICKEL COMPOSITES WITH TITANIUM NITRIDE OR TITANIUM CARBIDE
M.A.Haldane et al. (University of Alberta, Canada.) It was noted that TiNi shape memory alloys have high wear resistance. The shape memory effect was discussed. It was suggested that TiNi with additions of TX or TiN could have superior wear properties and retain the shape memory properties. Vacuum sintered TiNi-Tic was prepared from powder. Wear resistance was studied, by pin-on-disc tests and microstructures were investigated. Wear mechanisms were characterized by SEM. MARTENSITIC TRANSFORMATIONS IN TITANIUM-NICKEL-COPPER SHAPE MEMORY ALLOYS
et al. (Gyeongsang National University, Korea.) TiNi and TiNiCu powders were processed by ball milling and martensitic transformations characterized by differential scanning calorimetry. The powders showed reversible martensitic
N.T.Hun
MPR January 2000 39
transformations except when milled above 250 rpm when changes were not reversible and there were no endo- or exothermic peaks in the calorimetry curves. There were clear peaks for powders milled at 100 rpm. It was noted there were effects possibly due to grain size and contamination. SYNTHESISAND PROPERTIES OF TITANIUM-NICEELMEMORY ALLOYS MADE FROM ELEMENTAL POWDERS SStover et al. (Forschungzentrum Julich GmbH, Germany) It was reported that TiNi shape memory alloys can be made from elemental powders by HIP more successfully than by other PM methods. Dilatometry was used to monitor dimensional change. Effects of process variables were studied. In some cases the HIP material showed shape memory effects and in others heat treatment was required. Mechanical and fracture properties of alloys made by HIP from elemental powders were compared with those of alloys made from prealloyed powder by other means.
Metal injection modding FACTORS INFLUENCINGANY DECISION TO ENTER THE METAL INJECTION MOULDING MARKET G.C.Howard, M.Zedalis. (Columbia Powder Injection Moulding, Inc, USA.) Metal injection moulding (MIMI was discussed with regard to the factors that must be considered when deciding whether or not to enter the market for MIM stainless steel parts. DEFECTS IN INJECTION MOULDED PARTS AND REASONS FOR THEM U.Haupt, H.Walcher. (Arburg GmbH, Germany.) Defects, and the reasons for them, in injection moulded metal parts, were discussed. Some, such as residual stresses, jetting and voids, were identified. Causes were considered to include poor mould design and equipment selection or use of false parameters. It was noted that some defects may have multiple causes. Defects, their detection and some countermeasures were given. ADVANCES IN POWDERFLOm INJECTION MOULDING R. van Weeren, M.Zedalis. (Allied Signal, Inc, USA.) A PowderFloTMtechnique for production of parts was described. This uses a water-based fluidizing agent and a small amount of organic binder, which has plastic-like properties. After shaping the part only requires drying and can then be sintered. Lengthy debinding
40 MPR January 2000
is avoided. The technique can be used for thin and thick sections, operates at low pressures and temperatures and can be used with soft tooling. CORROSION RESISTANCE OF INJECTION MOULDED STAINLESS STEEL M.O.Speidel et al. (BASF AG, Germany.) Corrosion properties of a range of MIM stainless steels, some were Nifree austenitic grades, were investigated by a variety of tests. It was reported that the corrosion properties of MIM stainless steels were similar to those of cast/wrought alloys. Selection of materfor some applications, was id, d&cussed with reference to corrosion properties. STRUCTURE AND PROPERTIES OF STAINLESS STEEL INJECTION MOULDED WITH AQUEOUS BINDER et al. (Allied Signal J.C.LaSalle Research and Technology, USA.) Applications of 17-4PH stainless steel, in automotive uses, were discussed with reference to mechanical and corrosion properties and the use of MIM for part production. MIM with a water based binder was described. Tensile and fatigue properties were investigated. A sintering regime, to give 99% density and
INJECTION MOULDING OF MECHANICALLYALLOYED POWDERS
similar to those of cast/wrought HastelloyX and a 718 alloy. PERFORMANCE OF CARBONYL IRON POWDER WITB A NEW INJECTION MOULDING BINDER P.H.Booker et al. (Thermal Technology, Inc, USA.) It was reported that a feedstock with 59.5% carbonyl Fe and 2%Ni had been injection moulded with a novel binder. This allowed lower temperatures and pressures to be used in moulding and gave clean debinding. Moulding, debinding and sintering were evaluated with regard to satisfactory process steps and were discussed. EFFECTS OF PROCESS CONDITIONS ON STRUCTURE AND PROPERTIES OF INmTION MOULDED TOOL STEEL S.Komatsu et al. (Kinki University, Japan.) Conditions for debinding, sintering and heat treatment of injection moulded tool steel, made from water or gas atomized powders with a polyamide binder, were investigated. Process conditions were described. Structures and mechanical properties were determined and correlated with process parameters. It was shown that the properties of MIM tool steels could approach those of wrought materials by control of the process conditions.
Hard metal processing COMPARISON OF PROPERTIES OF
COBALTPOWDERSFOR BARD METALS
J.A.Sago et al. (University of Missouri, USA.) It was reported that powders for MIM, including 17-4PH stainless steel and NiTi shape memory alloy, had been mechanically alloyed prior to mixing the feedstock. Materials were processed to near net shape, near full density and with low levels of contamination. The characteristics of mechanically alloyed powders, which give successful MIM parts, were demonstrated. Process data, structures and properties were presented.
M.J.H.Ruscoe, D.Yuan. (Umex, Inc, Canada.) Processes for production of Co powders were outlined with reference to impurities, C and 0, and properties. Co particle sizes are related to application, examples being submicron sizes used for surgical drills and 8 pm for hot work rolls. Chemical, hydrometallurgical and thermal reduction processes were shown to produce particle sizes suitable for all applications.
NICKEL BASE SUPERALLOYS INJECTION MOULDED WITH AQUEOUS BINDER
GRAIN BOUNDARY PINNING OF PM COBALT BY OXIDES STUDIED BY IMAGE ANALYSIS
et al. (Allied Signal J.C.LaSalle Research and Technology, USA.) Use of Ni base superalloys for aerospace parts was discussed with respect to properties and use of injection moulding, with an aqueous base binder, for component production. A study of tensile and fatigue properties of MIM test bars, to optimize properties, was described. It was reported that 99% density could be attained, with mechanical properties
S.Lauper et al. (E.P.F.L., Switzerland.) It was noted that Co may oxidize during hot pressing of hard metals. A recent technique was shown to allow direct observation of oxides, on and off grain boundaries where the effects differ. Submicron Co powder was reported to have high stability. Hardness was discussed with respect to the Hall-Petch relationship and models such as the Zener model.
T.de Carvalho et al. (Belgo Brasiliera Ltda, Sao Paulo, Brazil.) The need to control process variables in order to attain dimensional stability of sintered steels was emphasized. It was reported that the use of an organic binder, in the powder mixture, was effective in minimizing segregation. The effects of organic binders on dimensional stability of compacted and sintered steels were evaluated.
Hard materials MICROSTRUCTURAL EVOLUTION CEMENTED CARBIDES DURING SINTERING
IN
O.Lavergne et al. (CERMeP, Grenoble, France.) Microstructural development, during liquid phase sintering of cemented carbides, was discussed with reference to normal and abnormal grain growth, inhibition by additives and measurements to quantify structural evolution. It was shown that the initial size of WC grains and matrix composition are the main factors in structural evolution and that these effects are still observed in the presence of grain growth inhibitors. TRE BORDERLINE BETWEEN CERMET AND BARDMETAL
T.Viatte et al. (Teledyne Metalworking Products, LaVergne, USA.) Studies of materials containing different proportions of Ti(C,N) and WC, with a Co binder and MO& as grain growth inhibitor, were described. It is reported that if Ti(C,N) is dominant in the hardmetal skeleton the structure is cubic and hexagonal if WC predominates. These accept plastic deformation differently and control high temperature mechanical properties. Some samples had very fine structures with high contiguity, high hardness and good high temperature mechanical properties. PHASE COMPOSITION AND CUTTING PROPERTIES OF CEMENTED CARBIDE TOOL INSERTS
E.Dudkin et al. (Volgograd State University, Volgograd, Technical Russia.) Correlation between composition of cutting tools, cutting performance and thermo-electromotive force (EMF) was discussed. Measurements of thermoEMF were used in a study of phase composition during a cutting operation as an alternative to measurement of temperature. Use of the method to control cutting operations was recommended.
WEAR OF TITANIUM BARDMETALS
CARBIDE
BASE
et al. (Tallinn Technical University, Tallinn, Estonia.) Adhesive and abrasive-erosive wear mechanisms for WC and TiC base materials were compared experimentally. It was concluded that abrasive-erosive wear resistance depends on rigidity of the material, for which WC materials were better than TiC alloys. Adhesive wear resistance was more structure sensitive than for abrasive-erosive wear, being related to the properties and composition of the matrix in respect of plastic deformation. TIC bonded with high strength steel was comparable with WC materials for adhesive wear. J.Kubarsepp
PM2TEC’99. The Abstracts that follow are of papers presented at the 1999 International Conference on Powder which was held in Vancouver,
et al. (OMG Americas, USA.) Use of PM stainless steel in automotive exhaust systems was discussed. It was noted that additions of Ni improve corrosion and thermal fatigue properties. Data on thermal fatigue resistance and corrosion properties of Ni modified PM 400 series stainless steels were presented. P.K.Samal
OF PM
et al. (Pennsylvania State University, USA.) Applications of stainless steels in automotive applications were discussed with regard to the need to develop design and analysis techniques to generate materials capable of withstanding severe service conditions. An investigation of creep properties of materials at 677°C was undertaken, with and without pre-corrosion of samples. Low steady state creep rates were found for 304L and 434L steels, although these behaved differently at fracture. Precorrosion had no noticeable effect. The study was said to indicate the suitability of stainless steel for automotive applications.
A.E.Segall
OF MACHINING
PM STAINLESS
R.J.Causton et al. (Hoeganaes Corp, Riverton, USA.) Improvements in compressibility, green and sintered mechanical properties of high performance sintered stainless steels were reviewed with examples of ferritic and austenitic powders which give such improvements. Consideration was given to automotive applications. EVALUATION OF FACTORS AFFECTING DIMENSIONAL CIIANGE DURING SINTERING OF PM STAINLESS STEELS
IMPROVEMENT IN MECRANICAL PROPERTIES OF PM STAINLESS STEEL BY NICKEL ADDITIONS
EFFECTS
HIGH PERFORMANCE STEELS
Canada,
Stainless steel
CREEP AND CORROSION STAINLESS STEELS
It was noted that stainless steels, except 304L, have poor machinability due to rapid work hardening and that MnS or MoS, may be added to enhance machinability, which may also be affected by sintering atmosphere. Effects of additions of MnS and MoS, on machinability, corrosion and mechanical properties of 316L stainless steel, sintered in H or dissociated ammonia were investigated and the results were discussed.
ADDITIVES
ON CORROSION AND MECRANICAL PROPERTIES OF STAINLESS STEEL
J.B.Terell, P.K.Samal. (OMG Americas, USA.)
J.H.Reinshafgen, G.D.Flick, (Ametek, USA.) Factors influencing dimensional changes during sintering of stainless steel were reviewed with regard to the need to understand these factors. Some of these factors were discussed, as quantitatively as possible, with consideration of inter-relationships.
Shape memory alloys TIT--NICKEL COMPOSITES WITH TITANIUM NITRIDE OR TITANIUM CARBIDE
M.A.Haldane et al. (University of Alberta, Canada.) It was noted that TiNi shape memory alloys have high wear resistance. The shape memory effect was discussed. It was suggested that TiNi with additions of TX or TiN could have superior wear properties and retain the shape memory properties. Vacuum sintered TiNi-Tic was prepared from powder. Wear resistance was studied, by pin-on-disc tests and microstructures were investigated. Wear mechanisms were characterized by SEM. MARTENSITIC TRANSFORMATIONS IN TITANIUM-NICKEL-COPPER SHAPE MEMORY ALLOYS
et al. (Gyeongsang National University, Korea.) TiNi and TiNiCu powders were processed by ball milling and martensitic transformations characterized by differential scanning calorimetry. The powders showed reversible martensitic
N.T.Hun
MPR January 2000 39
transformations except when milled above 250 rpm when changes were not reversible and there were no endo- or exothermic peaks in the calorimetry curves. There were clear peaks for powders milled at 100 rpm. It was noted there were effects possibly due to grain size and contamination. SYNTHESISAND PROPERTIES OF TITANIUM-NICEELMEMORY ALLOYS MADE FROM ELEMENTAL POWDERS SStover et al. (Forschungzentrum Julich GmbH, Germany) It was reported that TiNi shape memory alloys can be made from elemental powders by HIP more successfully than by other PM methods. Dilatometry was used to monitor dimensional change. Effects of process variables were studied. In some cases the HIP material showed shape memory effects and in others heat treatment was required. Mechanical and fracture properties of alloys made by HIP from elemental powders were compared with those of alloys made from prealloyed powder by other means.
Metal injection modding FACTORS INFLUENCINGANY DECISION TO ENTER THE METAL INJECTION MOULDING MARKET G.C.Howard, M.Zedalis. (Columbia Powder Injection Moulding, Inc, USA.) Metal injection moulding (MIMI was discussed with regard to the factors that must be considered when deciding whether or not to enter the market for MIM stainless steel parts. DEFECTS IN INJECTION MOULDED PARTS AND REASONS FOR THEM U.Haupt, H.Walcher. (Arburg GmbH, Germany.) Defects, and the reasons for them, in injection moulded metal parts, were discussed. Some, such as residual stresses, jetting and voids, were identified. Causes were considered to include poor mould design and equipment selection or use of false parameters. It was noted that some defects may have multiple causes. Defects, their detection and some countermeasures were given. ADVANCES IN POWDERFLOm INJECTION MOULDING R. van Weeren, M.Zedalis. (Allied Signal, Inc, USA.) A PowderFloTMtechnique for production of parts was described. This uses a water-based fluidizing agent and a small amount of organic binder, which has plastic-like properties. After shaping the part only requires drying and can then be sintered. Lengthy debinding
40 MPR January 2000
is avoided. The technique can be used for thin and thick sections, operates at low pressures and temperatures and can be used with soft tooling. CORROSION RESISTANCE OF INJECTION MOULDED STAINLESS STEEL M.O.Speidel et al. (BASF AG, Germany.) Corrosion properties of a range of MIM stainless steels, some were Nifree austenitic grades, were investigated by a variety of tests. It was reported that the corrosion properties of MIM stainless steels were similar to those of cast/wrought alloys. Selection of materfor some applications, was id, d&cussed with reference to corrosion properties. STRUCTURE AND PROPERTIES OF STAINLESS STEEL INJECTION MOULDED WITH AQUEOUS BINDER et al. (Allied Signal J.C.LaSalle Research and Technology, USA.) Applications of 17-4PH stainless steel, in automotive uses, were discussed with reference to mechanical and corrosion properties and the use of MIM for part production. MIM with a water based binder was described. Tensile and fatigue properties were investigated. A sintering regime, to give 99% density and
INJECTION MOULDING OF MECHANICALLYALLOYED POWDERS
similar to those of cast/wrought HastelloyX and a 718 alloy. PERFORMANCE OF CARBONYL IRON POWDER WITB A NEW INJECTION MOULDING BINDER P.H.Booker et al. (Thermal Technology, Inc, USA.) It was reported that a feedstock with 59.5% carbonyl Fe and 2%Ni had been injection moulded with a novel binder. This allowed lower temperatures and pressures to be used in moulding and gave clean debinding. Moulding, debinding and sintering were evaluated with regard to satisfactory process steps and were discussed. EFFECTS OF PROCESS CONDITIONS ON STRUCTURE AND PROPERTIES OF INmTION MOULDED TOOL STEEL S.Komatsu et al. (Kinki University, Japan.) Conditions for debinding, sintering and heat treatment of injection moulded tool steel, made from water or gas atomized powders with a polyamide binder, were investigated. Process conditions were described. Structures and mechanical properties were determined and correlated with process parameters. It was shown that the properties of MIM tool steels could approach those of wrought materials by control of the process conditions.
Hard metal processing COMPARISON OF PROPERTIES OF
COBALTPOWDERSFOR BARD METALS
J.A.Sago et al. (University of Missouri, USA.) It was reported that powders for MIM, including 17-4PH stainless steel and NiTi shape memory alloy, had been mechanically alloyed prior to mixing the feedstock. Materials were processed to near net shape, near full density and with low levels of contamination. The characteristics of mechanically alloyed powders, which give successful MIM parts, were demonstrated. Process data, structures and properties were presented.
M.J.H.Ruscoe, D.Yuan. (Umex, Inc, Canada.) Processes for production of Co powders were outlined with reference to impurities, C and 0, and properties. Co particle sizes are related to application, examples being submicron sizes used for surgical drills and 8 pm for hot work rolls. Chemical, hydrometallurgical and thermal reduction processes were shown to produce particle sizes suitable for all applications.
NICKEL BASE SUPERALLOYS INJECTION MOULDED WITH AQUEOUS BINDER
GRAIN BOUNDARY PINNING OF PM COBALT BY OXIDES STUDIED BY IMAGE ANALYSIS
et al. (Allied Signal J.C.LaSalle Research and Technology, USA.) Use of Ni base superalloys for aerospace parts was discussed with respect to properties and use of injection moulding, with an aqueous base binder, for component production. A study of tensile and fatigue properties of MIM test bars, to optimize properties, was described. It was reported that 99% density could be attained, with mechanical properties
S.Lauper et al. (E.P.F.L., Switzerland.) It was noted that Co may oxidize during hot pressing of hard metals. A recent technique was shown to allow direct observation of oxides, on and off grain boundaries where the effects differ. Submicron Co powder was reported to have high stability. Hardness was discussed with respect to the Hall-Petch relationship and models such as the Zener model.