Origins of defects were outlined for a range materials and shapes and solutions proposed. The need to alter a design to optimize a part was noted. SIMULATION OF INJECTION MOULDING DIE FILLING FOR COMPLEX SHAPED CAVITIES J.H. Lee et al. (Pohang University of Science and Technology, Pohang, Korea). Limitations in earlier work using finite element and difference methods for study of flow in injection moulding were discussed. It was reported that a more generalized simulation, capable of dealing with thick and thin sections of parts had been developed.
Fatigue SURFACE FATIGUE OF PM NICKEL STEEL J.R. Spirko, H.I. Sanderow (Concurrent Technologies Corp, USA). Surface fatigue was discussed with reference to gear, cam and sprocket applications. The effect of density on spalling and pitting of a Ni steel was investigated. Surface endurance limits were determined in rolling and rolling/sliding contact fatigue tests. The results were compared with data for wrought steels. THERMOMETRICAL INVESTIGATION OF FATIGUE OF POWDER FORGED CONNECTING RODS A. Piotrowski, D. Eifler (University of Essen, Germany). Fatigue of powder forged steel connecting rods was investigated under constant amplitude and short time conditions at ambient temperature. Microstructure changes and softening during testing were studied. The tests were reported to allow evaluation of cyclic deformation to failure of the alloys studied and to estimate the fatigue limit. INFLUENCE OF MANGANESE SULPHIDE ON FATIGUE OF A DISTALOY AE CARBON STEEL A. Bergmark (Lund University, Sweden). The effect of 0.5%MnS on fatigue of Distaloy AEO.5%C steel, as a function of density was investigated. Fatigue limits reported were 218, 235 and 320 MPa at 7.15, 7.45 gm.cmm3and full density without MnS. MnS had no effect at full density on the fatigue limit. MnS reduced the fatigiue limit by 5-10% at lower than full density.
Metal matrix composites EFFECT OF PARTICLE SHAPE ON FRACTURE OF PM MAGNESIUM ALLOY MATRIX COMPOSITE KU. Kainer et al.
Clausthal, Germany). Light alloy matrix composites were discussed with regard to structure, properties and applications. Low fracture properties were noted. The effects of additions of Sic particles on fracture toughness of Mg alloy AZ91 were investigated with regard to particle shape characteristics and discussed in terms of fractography. POROUS IRON-IRON COMPOSITE AS AN ENVIRONMENT CONSCIOUS MATERIAL N. Itsubo et al. (University of Tokyo, Tokyo, Japan). Fe/Fe composites, reinforced with drawn Fe fibre, were investigated with reference to recyclability of the materials. Samples were made by sintering ultrafine Fe powder with the Fe iibre at 450°C. The composite was shown to have improved properties compared with sintered ultraiine Fe powders. DEVELOPMENT OF FORGED PM ALUMINIUM-SILICON ALLOY FOR CONNECTING RODS H. Shikata et al. (Hitachi Powdered Metals Co Ltd, Japan). Investigations, aimed at the development of connecting rods made from forged AI-Si alloys, were described. PM Al-Si alloys were made and characterized for structure, wear resistance and mechanical properties. The wear resistance was improved by dispersing pro-eutectic Si as small particles. The ductility was increased by trace elements and heat treatment. PM AI-Si connecting rods were reported to be 30% lighter than die cast rods. FORGING OF PM ALUMINIUM-SILICON CARBIDE COMPOSITE S. Szczepanik (University of Mining and Metallurgy, Poland). Results of investigation of the formability of Al-5%SiC particle composites were presented. Production and testing methods, on a servo-hydraulic machine, were described. Relationships between flow stress, strain rate and reduction ratio were established. It was reported that composites made from Al and Sic powders had good formability. Joining PM ADVANCES WITH BRAZING TECHNOLOGY W.V. Knopp (PM Engineering and Consulting Co, USA). It was reported that an alloy, for brazing PM ferrous parts and based on Cu-Ni-MnSi-B, has been developed. The melting point was 980°C and the alloy flowed into pores
in the base metal. The joint strength was 27 ton.inm2.Cu infiltration of a part with a brazed joint, without reducing the strength of the joint, was shown to be possible. JOINING OF DIE PRESSED PM PARTS TO CONVENTIONAL STEELS BY DIFFUSION BONDING H. Cohrt et al. (Schunk Sintermetalltechnik, Germany). Joining of PM parts by welding and brazing was discussed but with particular emphasis on diffusion bonding. Technology of diffusion bonding die pressed parts to other steels was outlined with respect to fitting conditions, influence of different materials and heat treatment. An example was described. JOINING OF STEEL AND PARTICLE REINFORCED PM ALUMINIUM BY SINTER BRAZING H. Danninger et al. (Technical University of Vienna, Austria). Brazing of particle reinforced Al alloy pulleys on to Fe hubs during sintering was investigated with regard to the brazing alloys used. Conventional brazing alloys were shown to be not particularly suitable. Sound joints were obtained with Cu alloys. The importance of optimizing brazing was emphasized in terms of the amount of brazing alloy, clearances and process conditions.
Warm compaction DYNAMIC PROPERTIES OF WARM COMPACTED SINTERED HIGH STRENGTH STEELS 0. Mars (Hans AB, Sweden). It was reported that using warm compaction density of sintered steel up to 7.4 gm.cm? can be attained by a singlepress/single-sinter route and that this results in increased mechanical properties. The influence of warm compaction on dynamic properties of sintered steels was described. Data for warm compacted steels and steels made by other methods were compared for specimens at the same and lower densitites. Relationships between fatigue strength, density and pore morphology were discussed. EVALUATION OF HIGH PERFORMANCE MATERIALS PROCESSED USING WARM COMPACTION TECHNOLOGY I.W. Donaldson (The PresMet Carp, USA). Relationships between microstructure, pore size and distribution and mechanical properties of PM materials were discussed. Note was taken of effects of alloying. It was reported that good mechanical properties had been attained at densities above 7.3 gm.cmm3achieved by different methods, one of which involved warm compaction.
MPR December 1996 39