A major advance in powder metallurgy

Ultramet has developed a process which promises to significantly increase the mechanical properties of powder metallurgy (PM) parts. Current PM technology uses mixed powders of various constituents prior to compaction. The homogeneity and flaw distribution in PM parts depends on the uniformity of mixing and the maintenance of uniformity during compaction. Conventional PM fabrication processes typically result in non-uniform distribution of the matrix, flaw generation due to particle-particle contact when one of the constituents is a brittle material, and grain growth caused by high temperature, long duration compaction processes. Additionally, a significant amount of matrix material is usually necessary to fill voids and create 100 percent dense parts. In Ultramet's process, each individual particle is coated with the matrix material, and compaction is performed by solid state processing. In this program, Ultramet coated 12-micron tungsten particles with approximately 5 wt percent nickel/iron. After compaction, flexure strengths were measured 50 percent higher than those achieved in conventional liquid phase sintered parts (10 wt percent Ni/Fe). Further results and other material combinations are discussed

High value timber composite panels from hardwood plantation thinnings.

Identifying processing strategies and products that suit young plantation hardwoods has proved challenging with low product recoveries and/or unmarketable products being the outcome of many trials. The production of rotary veneer has been demonstrated as an effective method for converting plantation hardwood trees. Across nine processing studies that included six different plantation species (Dunn’s white gum, spotted gum, Gympie messmate, spotted gum hybrid, red mahogany and western white gum), simple spindleless lathe technology was used to process 914 veneer billets totally 37.4 m3

Research program to develop a technology improvement program for closed die forging Final report

Upset forging tests on aluminum and titanium alloys and maraging steel using high temperature die

Crystalline-state extrusion of low density polyethylenes/

Three low density polye thylenes , one long branched (A) and two linear (B and C), have been solid-state extruded at different temperatures from ambient to 80°C and to draw ratios _\u3c 8. The densities and melt indices of A, B and C are 0.920, 0.920 and 0.935 g/cm3 , and 1.9, 0.8 and 1.2 respectively. Melt crystallized billets were extruded through conical dies in an Instron Capillary Rheometer. The linear polymers draw more easily than the branched. All three strain-harden. Density, birefringence, tensile and thermal properties have been evaluated as functions of extrusion temperature and draw ratio. Despite some loss through die swell, substantial orientation takes place during solid-state extrusion as evidenced by increases in transparency, birefringence, tensile modulus (up to 4.5 times that of the original isotropic polymer) and thermal conductivity. No ma j or changes in crystallinity were observed as assessed by density and DSC measurements. Depending on the polymer and the draw temperature, density does go through a minimum or shows a monotonic increase with draw

Service performance of refractories in connection with pusher reheating furnaces in Bhilai Steel Plant

Bhilai Steel Plant comprises of three finishing mills, which are equipped with continuous pusher reheating furnaces to heat blooms & billets from the blooming & billet mill at 2.5 M. T. stage. Reheating furnaces of rail & structural mill and merchant mill are of same design with three zones having 20 burners in each furnace (7 burners in top & bottom zone & 6 burners in soaking zone). The wire rod mill has got only one reheating furnace with 2 zones having 14 burners in each zone

Tungsten wire/FeCrAlY matrix turbine blade fabrication study

The objective was to establish a viable FRS monotape technology base to fabricate a complex, advanced turbine blade. All elements of monotape fabrication were addressed. A new process for incorporation of the matrix, including bi-alloy matrices, was developed. Bonding, cleaning, cutting, sizing, and forming parameters were established. These monotapes were then used to fabricate a 48 ply solid JT9D-7F 1st stage turbine blade. Core technology was then developed and first a 12 ply and then a 7 ply shell hollow airfoil was fabricated. As the fabrication technology advanced, additional airfoils incorporated further elements of sophistication, by introducing in sequence bonded root blocks, cross-plying, bi-metallic matrix, tip cap, trailing edge slots, and impingement inserts

Modelling and experimental study of the spray forming of dissimilar metals

This research describes a systematic study to develop a strong interfacial bond in as-sprayed dissimilar metallic alloys. Non-destructive three-dimensional microstructure and residual stress characterisations via X-ray micro-computed tomography and neutron diffraction, respectively and numerical modelling of the preform shape evolution, transient heat flow and thermal residual stress developed were employed. The study revealed quantitatively the links between the key spray forming parameters, corresponding microstructures formed and the interfacial bonding characteristics in thick as-sprayed dissimilar metallic alloys.The key novelties of this research include:- The development of a preform shape and heat flow model that incorporates: (1) the use of a mesh deformation method with automated re-meshing algorithm to model the growing preforms and address the coupling of droplet mass/enthalpy input at the deposition surface and (2) a substrate induction preheating model.- Validated against experimental measurements, the preform heat flow model was used to establish the correlations between the preform thermal history and microstructures formed. The correlations established based on the tomography and diffraction measurements showed their interrelationship and agreements with one another. The correlations also provided the crucial links to take into account the effects of the microstructure formed on the corresponding material properties and stresses developed in the preform after cooling.- The combined use of thermal residual stress modelling and neutron diffraction in this research presents, for the first time, the nondestructive quantitative assessment of the interfacial bonding in thick as-sprayed dissimilar steels preforms. The effects of different substrate and spray temperatures on the microstructures, residual stress and interfacial bond developed were investigated systematically.- The dynamics of the atomised droplets rapid microstructural change during deposition were revealed when subjected to rapid Joule heating (~500 K s-1) to a range of isothermal temperatures in the vicinity of the precipitate solvus and alloy solidus temperatures with a short (~10 s) high temperature holding time. A finite element model of the transient heat flow in the powder compact was developed to provide more quantitative information of the specimen internal temperature distribution which was otherwise unavailable and the rapid microstructural change in the powders was rationalised in terms of the transient temperature conditions. These results can be useful in reconciling thermal histories and microstructures in the as-sprayed preforms, and may guide the optimisation of the spray forming process if desirable microstructural features are to be preserved into the bulk preform.- The elastic and plastic deformation behaviours of the spray formed steels containing different levels of porosity and the integrity of the bonded interface of the spray formed dissimilar steels were studied in situ via three-point bend tests with neutron diffraction. The study revealed the role of the constituent phases in the as-sprayed high speed steel when subjected to stresses above the elastic limit and the characteristics of the interfacial bond formed in comparison to the non-destructive assessment carried out in this research