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Dimensional predictability and consistency in aircraft parts
Samples of Inconcl718 were prcpared from gas atomized powder by HIP to full density. Samples made from N and Ar atomized powders were compared. Structures were fine and homogeneous and resisted grain growth during heat treatments. Mechanical properties exceeded standard specification requirements in tests of properties. MICROSTRUCTURE AND PROPERTIES OF CHROMIUM-COBALTMOLYBDENUM MEDICAL IMPLANT MATERIALS II.E.Hanninen et al. (Helsinki University of Technology, Helsinki, Finland. 1 Use of Cr-Co-MO alloys in surgical prostheses was discussed with reference to developments to enhance performance on metal-on-metal articulating joints. N can enhance properties but fabrication of alloys with N is difficult. In the study described alloy powders were controllably nitrided in a fluidized bed and fabricated by HIP. The resulting materials were shown to have fine microstructures, no residual porosity, improved mechanical properties and increased critical crevice corrosion temperatures.
PM alloy steels FLEXURAL FATIGUE IN AUSFORMED SINTERED STEEL R.A.Queeney, P.Latinski. (Pennsylvania State University, USA.) Surface deformation of sintered steels was discussed with regard to performance under extreme surface stressing, which was said to be as good as wrought steel. Flexural fatigue of AISI4685 steel, which had been surface ausformed - that is, deformed in the metastable austenitic state, was investigated. Ausforming reduced surface porosity and imparted a structure with increased endurance. Comparison was made with wrought and heat treated steel, and the surface treated steel could be the more durable. BINDER TREATED ANALOGUES OF DIFFUSION ALLOYED STEELS F.J.Semel. (Hoeganaes Corp, USA.) Properties, at two %C levels, of binder treated steel analogues of diffusion alloyed steels, were presented. These were prepared without diffusion alloying. Comparison was made between these steels and steels made by diffusion alloying in respect of properties, in powder and green states, and dimensional changes during processing.
COMPARISON OF SINTERED STEELS AND MALLEABLE CAST IRON
EFFECTS OF TEMPERING TEMPERATURE ON SINTER HARDENED STEEL
F.J.Hanejko, A.J.Raw1ing.s. (Hoeganaes Corp, USA.) The mechanical properties of malleable cast iron were compared with those of steels made by Ancordense processing. It was shown that PM steels can replace malleable cast iron parts.
M.Gagne, F.Chagnon. (Quebec Metal Powders Ltd, Canada.1 A study of the effects of tempering temperature on mechanical properties of sinter hardened steel was described. Samples of Fe-2%&u-(0.65 or 0.8WC steel were pressed and sintered, at 112O”C, to a density of 6.8 g.cmm3. The cooling rate was 0.7”C.s-’ from 870 to 650°C. Tempering was for 1 hour at 150 to 600°C. The steels were characterized for structure and mechanical properties.
Powder injection moulding METAL PARTS FROM PLASTIC TOOLS J.M.Schoonover. (Allied Signal, USA.) Development of a water-based moulding system, for powders, was reported. Low pressures and temperatures allow use of plastic tooling to make metal and ceramic parts. The moulds are made of epoxy or urethane with Al or graphite filler. The mould cavity is made by casting onto a pattern. Tool life can he a few parts or thousands. INJECTION MOULDING SIMULATION OF MOULD FILLING GPBacker. (Flow Logic, USA.) Modelling and simulation of powder injection moulding were discussed. Use has been made of software for plastic materials but this requires modification for metallic and ceramic materials to take effects of solid particles into account. Differences between plastics and powder injection moulding were considered. Improved procedures for modelling PIM were proposed. DIMENSIONAL PREDICTABILITY AND CONSISTENCY IN AIRCRAFT PARTS et al. (Columbia Powder B.Holmes Injection Moulding Inc, USA.) A study of dimensional changes in a complex shaped 17-4PH stainless steel aircraft part, made by injection moulding with a water based binder, was described. The object was to determine predictability of shrinkage and part-topart consistency
Sinter hardening A SUPERIOR SINTER HARDENING MATERIAL R.Causton et al. (Hoeganaes Corp, USA. 1 Sinter hardening was discussed with regard to improved process efficiency, reduced costs and reduction of process problems. It was reported that a new sinter hardening steel had been developed that allowed higher densities and mechanical properties to be attained. The investigations leading to these improvements were reviewed.
EVALUATION OF HARDENABILITY AND COMPRESSIBILITY FOR OPTIMIZATION OF SINTER HARDENING STEEL B.Julien, G.L’Esperance. (Domfer Metal Powders Ltd, Canada.) Powders used for sinter hardening parts were reviewed. It was noted that powder compressibility decreases as hardenability increases. A number of steel powders were evaluated to determine and select the most appropriate powders for sinter hardening.
Composite
materials
MICROSTRUCTURE DEVELOPMENT DURING SINTERING OF NICKEL ALUMINIDE-TITANIUM CARBIDE D.Barker et al. (Oak Ridge National Laboratory, USA.) It was reported that N&Al-Tic materials were under development for diesel engine applications. Compacts were fabricated with 30 to 50% binder, vacuum sintered and low gas pressure HIPed. Densification was enhanced by additions of MO or Si and inhibited by Cr and Zr. Ti and Fe had little effect on densification. Increase in ‘%Ni,Al increased densification when prealloyed powders were used. When N&Al was formed by in situ synthesis from Ni and NiAl densification was impaired. Structures consisted of TIC cores with Ni,(Al,Ti) rims. SOFT MAGNETIC COMPOSITES (Hogan& AB, Hoganas, P.Jansson. Sweden.) Applications of soft magnetic composites, formed from Fe powders with an electrically insulating coating, for frequencies of 50 Hz to 1 MHz, were discussed. Samples were prepared from sponge and water atomized powders, in sizes ranging from less than 45 pm to above 145 pm. The sizes used were optimized for the intended frequency. Inorganic coatings were used for low frequency applications and organic layers for high frequencies. Heat treatments were used to reduce hysteresis losses.
MPR June 2000
39
PM alloy steels FLEXURAL FATIGUE IN AUSFORMED SINTERED STEEL R.A.Queeney, P.Latinski. (Pennsylvania State University, USA.) Surface deformation of sintered steels was discussed with regard to performance under extreme surface stressing, which was said to be as good as wrought steel. Flexural fatigue of AISI4685 steel, which had been surface ausformed - that is, deformed in the metastable austenitic state, was investigated. Ausforming reduced surface porosity and imparted a structure with increased endurance. Comparison was made with wrought and heat treated steel, and the surface treated steel could be the more durable. BINDER TREATED ANALOGUES OF DIFFUSION ALLOYED STEELS F.J.Semel. (Hoeganaes Corp, USA.) Properties, at two %C levels, of binder treated steel analogues of diffusion alloyed steels, were presented. These were prepared without diffusion alloying. Comparison was made between these steels and steels made by diffusion alloying in respect of properties, in powder and green states, and dimensional changes during processing.
COMPARISON OF SINTERED STEELS AND MALLEABLE CAST IRON
EFFECTS OF TEMPERING TEMPERATURE ON SINTER HARDENED STEEL
F.J.Hanejko, A.J.Raw1ing.s. (Hoeganaes Corp, USA.) The mechanical properties of malleable cast iron were compared with those of steels made by Ancordense processing. It was shown that PM steels can replace malleable cast iron parts.
M.Gagne, F.Chagnon. (Quebec Metal Powders Ltd, Canada.1 A study of the effects of tempering temperature on mechanical properties of sinter hardened steel was described. Samples of Fe-2%&u-(0.65 or 0.8WC steel were pressed and sintered, at 112O”C, to a density of 6.8 g.cmm3. The cooling rate was 0.7”C.s-’ from 870 to 650°C. Tempering was for 1 hour at 150 to 600°C. The steels were characterized for structure and mechanical properties.
Powder injection moulding METAL PARTS FROM PLASTIC TOOLS J.M.Schoonover. (Allied Signal, USA.) Development of a water-based moulding system, for powders, was reported. Low pressures and temperatures allow use of plastic tooling to make metal and ceramic parts. The moulds are made of epoxy or urethane with Al or graphite filler. The mould cavity is made by casting onto a pattern. Tool life can he a few parts or thousands. INJECTION MOULDING SIMULATION OF MOULD FILLING GPBacker. (Flow Logic, USA.) Modelling and simulation of powder injection moulding were discussed. Use has been made of software for plastic materials but this requires modification for metallic and ceramic materials to take effects of solid particles into account. Differences between plastics and powder injection moulding were considered. Improved procedures for modelling PIM were proposed. DIMENSIONAL PREDICTABILITY AND CONSISTENCY IN AIRCRAFT PARTS et al. (Columbia Powder B.Holmes Injection Moulding Inc, USA.) A study of dimensional changes in a complex shaped 17-4PH stainless steel aircraft part, made by injection moulding with a water based binder, was described. The object was to determine predictability of shrinkage and part-topart consistency
Sinter hardening A SUPERIOR SINTER HARDENING MATERIAL R.Causton et al. (Hoeganaes Corp, USA. 1 Sinter hardening was discussed with regard to improved process efficiency, reduced costs and reduction of process problems. It was reported that a new sinter hardening steel had been developed that allowed higher densities and mechanical properties to be attained. The investigations leading to these improvements were reviewed.
EVALUATION OF HARDENABILITY AND COMPRESSIBILITY FOR OPTIMIZATION OF SINTER HARDENING STEEL B.Julien, G.L’Esperance. (Domfer Metal Powders Ltd, Canada.) Powders used for sinter hardening parts were reviewed. It was noted that powder compressibility decreases as hardenability increases. A number of steel powders were evaluated to determine and select the most appropriate powders for sinter hardening.
Composite
materials
MICROSTRUCTURE DEVELOPMENT DURING SINTERING OF NICKEL ALUMINIDE-TITANIUM CARBIDE D.Barker et al. (Oak Ridge National Laboratory, USA.) It was reported that N&Al-Tic materials were under development for diesel engine applications. Compacts were fabricated with 30 to 50% binder, vacuum sintered and low gas pressure HIPed. Densification was enhanced by additions of MO or Si and inhibited by Cr and Zr. Ti and Fe had little effect on densification. Increase in ‘%Ni,Al increased densification when prealloyed powders were used. When N&Al was formed by in situ synthesis from Ni and NiAl densification was impaired. Structures consisted of TIC cores with Ni,(Al,Ti) rims. SOFT MAGNETIC COMPOSITES (Hogan& AB, Hoganas, P.Jansson. Sweden.) Applications of soft magnetic composites, formed from Fe powders with an electrically insulating coating, for frequencies of 50 Hz to 1 MHz, were discussed. Samples were prepared from sponge and water atomized powders, in sizes ranging from less than 45 pm to above 145 pm. The sizes used were optimized for the intended frequency. Inorganic coatings were used for low frequency applications and organic layers for high frequencies. Heat treatments were used to reduce hysteresis losses.
MPR June 2000
39