In this paper, an interesting technical problem is to be solved concerning in particular composites with a metallic matrix and with continual strengthening fibres. The problem concerns metal ...transport in the liquid condition, using different pressure inlets and outlets of the form. The attempt to analyse the bonding among the fibres and metallic matrix is described. Analysis of the problem of bonding between the fibres and metallic matrix solved. Continuous fibre-reinforced metal matrix composites as a technological process is very interesting. Casting of continuous fibres is an especially appropriate fabrication technology when these materials are to be used in complex-shaped parts, or the components of an internal combustion engine. It is also an excellent method for producing these materials in thick section or in sections containing a variety of fibre orientations. However, casting in ambient atmosphere is not as well suited to the fabrication of thin, flat sheets, because of the difficulty in feeding molten metal over long distances through thin cross sections. If the pouring process is used in a high vacuum, we should expect very good or excellent results. In preparing the fibre preform, the arrangement of the fibres into the orientation, packing density and size desired in the finished part must be maintained. However, in both preform preparation and casting, significant modifications to the standard procedures must be made when casting metal composites.
Microstructure investigation and microhardness mapping were done on the material with ultra-fine grained structure prepared by constrained groove pressing of twin-roll cast AZ31 magnesium strips. The ...microstructure observations showed significant drop of the grain size from 200 gm to 20 gm after constrained groove pressing. Moreover, the heterogeneities in the microhardness along the cross-section observed in the as-cast strip were replaced by the bands of different microhardness in the constrained groove pressed material. It is shown that the constrained groove pressing technique is a good tool for the grain refinement of magnesium alloys.
Usitnjavanje zrna pod utjecajem intenzivnih plastičnih deformacija (IPD) na nižim temperaturama (ispod temperature rekristalizacije) i neuobičajno poboljšavanje svojstava takovih materijala se ...pokazalo stvarnim. Međutim, industrijska primjena je ograničena glede nedostatka efektivnog kontinuiranog procesa IPD. Razmatraju se mogućnosti razvitka kontinuiranog IPD procesa na temelju s jedne strane na kutno kanalnom prešanju (KKP), a s druge strane na kontinuiranoj ekstruziji ili procesu vučenja. Analiziraja se i postojanje različitih kontinuiranih IPD procesa za traku, šipkaste proizvode i žicu.
The influence of different heat treatments on the microstructure of ordered cuboidal γ′ precipitates in the ZS26 superalloy (wt%: Ni 64, W 11, Co 9, Al 6, Cr 5, Nb 1.5, Ti 1, Mo 1, V 1) was studied ...by small‐angle neutron scattering. The average shape and size of the precipitates were determined by modelling the scattering curves and by fitting them to the measured 2D data. The volume fraction of the precipitates was deduced from the fitted parameters under the assumption of a homogeneous distribution of particles inside the sample.
Based on analysis of austenite deformation behaviour during thermomechanical processing of Nb–Ti microalloyed steel, the rolling schedules were designed to produce (i) recrystallized austenite, (ii) ...unrecrystallized austenite, and (iii) ferrite-pearlite. The effects of austenite conditioning on the final ferrite-pearlite microstructure and mechanical properties of steel were investigated. To rationalise the variation in final ferrite grain size with different thermomechanical processing schedules, it is necessary to consider the ferrite grain growth in addition, to the density of ferrite nucleation sites. Mechanical properties were the means to evaluate the variation in austenite solutioning and deformation conditions introduced into individual applied rolling schedules. The benefit of tensile tests, especially yield strength and ductility values, in determining the optimum deformation schedule and coiling condition for given steel is demonstrated.
The static and the cyclic creep load-controlled tests of the nickel base single-crystal superalloy, CMSX 3 have been studied. In this study, two different testing procedures of cyclic creep were ...carried out under specific loading schedules defined by the stress amplitude, the stress range, stress ratio, and cycling frequency. The different cycling frequencies for two cycling hold periods were investigated to influence the creep/fatigue behaviour of the alloy. The influence of these variables was evaluated through the deformation behaviour and the fracture life data. It is concluded that the additional fatigue stress component superimposed onto creep stress component is of great significance influencing the deformation process and fracture life and accelerating the creep strain rate for chosen types of testing.
A non-destructive investigation of precipitate morphology in creep-exposed (900°C/300
MPa) CMSX3 single-crystal (Cr 8.0, Co 4.0, Mo 0.5, Al 5.7, W 9.0, Ti 0.7, Ta 5.7, Ni balance; wt%) using pin-hole ...SANS is presented. The experiment provided information on microstructural parameters for samples of 5
mm effective thickness.
The Udimet 500 nickel base superalloy blade exposed for 50000 hours in land base gas turbine working conditions faced the structure degradation. Six different heat treatments procedures have been ...applied (the blades were exposed at 900 °C and 1000 °C for different periods with maximum hold of 2500 hours) to rejuvenate the degraded structure. Metallographic work was performed, generally, aging at both temperatures modify the gamma prime size, morphology and distribution characteristics substantially. The volume fraction of secondary gamma prime decreased with increasing aging time.
Advanced High Strength Steels (AHSS), among them especially Dual Phase (DP) steels, Transformation Induced Plasticity (TRIP) steels, Complex Phase steels (PS), Partially Martensite (PM) steels, ...feature promising results in the field. Their extraordinary mechanical properties can be tailored and adjusted by alloying and processing. The introduction of steels with a microstructure consisting at least two different components has led to an enlargement of the strength level without a deterioration of ductility. Furthermore, the development of ultra fine-grained AHS steels and their service performance are reviewed and the new techniques are introduced. Various projects have been devoted to develop new materials for flat and long steel products for structural applications. The main stream line is High Strength, in order to match the weight lightening requirements that concern the whole class of load bearing structures and/or steel components and one of the most investigated topics is grain refinement.
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