DEVELOPMENT OF ALUMINIUM HOT ROLLING EMULSION

Sažetak Toplo valjanje aluminija predstavlja vrlo sofisticiranu tehnologiju. Različiti tipovi emulgirajućih ulja koriste se u tome postupku. Bliska suradnja između proizvođača maziva i krajnjega korisnika nužna je za razvoj novih maziva, jednako kao i za osiguravanje stalne proizvodnje. Prikazuje se suradnja pri razvijanju emulzije za reverzibilni quarto valjaonički stan, kadra udovoljiti tehničkim, okolišnim i gospodarskim zahtjevima. Ova studija prikazuje rezultate davno započeta razvoja.Abstract Hot rolling of aluminium is a very sophisticated technology. Different type water-soluble oils are used in this process. Close co-operation between the lubricant manufacturer and the end user is essential to develop both a new lubricant and provide continuous production. The authors would like to present the co-operative development work creating an emulsion for a reversing quarto mill, which is able to meet technical, environmental and economical requirements. The study shows the results of a long ago started development

Strengthening magnesium by design: integrating alloying and dynamic processing

Magnesium (Mg) has the lowest density of all structural metals and has excellent potential for wide use in structural applications. While pure Mg has inferior mechanical properties; the addition of further elements at various concentrations has produced alloys with enhanced mechanical performance and corrosion resistance. An important consequence of adding such elements is that the saturated Mg matrix can locally decompose to form solute clusters and intermetallic particles, often referred to as precipitates. Controlling the shape, number density, volume fraction, and spatial distribution of solute clusters and precipitates significantly impacts the alloy's plastic response. Conversely, plastic deformation during thermomechanical processing can dramatically impact solute clustering and precipitation. In this paper, we first discuss how solute atoms, solute clusters, and precipitates can improve the mechanical properties of Mg alloys. We do so by primarily comparing three alloy systems: Mg-Al, Mg-Zn, and Mg-Y-based alloys. In the second part, we provide strategies for optimizing such microstructures by controlling nucleation and growth of solute clusters and precipitates during thermomechanical processing. In the third part, we briefly highlight how one can enable inverse design of Mg alloys by a more robust Integrated Computational Materials Design (ICMD) approach

New Extension Services and Restructuring Farm Management Training Under Transition: A Pilot Project in Hungary

As a result of the radical political, social, and economic transition in process fundamental changes have been taking place in Hungarian agriculture concerning the outside environmental conditions of farm management (government policy, loss and alter of export markets, legislation ’'boom", etc.), as well as, in inside circumstances of farming operations (new land owners with limited knowledge and basic capital, decentralisation and privatisation of large-scale farm businesses, conversion of farm enterprise forms, etc. It has been a considerable effect on the requirements against information and human resources within all type of restructuring businesses. Most of the previous information and advisory services either have become obsolete or collapsed. By surveying the major objectives and achievements of a pilot project this paper presents how a local enterprise agency in Hungary has been able to respond to these changes. Although the greater part of the development work has not been carried out, but pilot advisory models and case studies elaborated during this regional development project have enabled to leam fundamental lessons and formulate further problem-oriented conclusions and considerations

Amorphous Hf-based foams with aligned, elongated pores

Warm equal channel angular extrusion is used to consolidate a blend of amorphous Hf44.5Cu27Ni13.5Ti5Al10 and crystalline W powders. Dissolution of the W phase results in ∼60% aligned, elongated pores within an amorphous Hf-based matrix exhibiting ductility in compression, but at lower strengths than similar amorphous Zr-based foams due to incomplete bonding between Hf-based powders

Characterization of uniaxial compressive response of bulk amorphous Zr-Ti-Cu-Ni-Be alloy

Uniaxial compressive response of bulk amorphous Zr-Ti-Cu-Ni-Be alloy, also called as Vitreloy-1, was investigated at quasistatic and high strain rates in the range of 10-3 and 103 s-1, respectively. The Vitreloy-1 specimens exhibited elastic response followed by catastrophic fracture along a narrow shear band. The ultimate strength of the specimens varied between 1800 and 2200 MPa irrespective of the strain rate and independent of the aspect ratio of the specimens. The quasistatically deformed specimens fractured into two or three large fragments. The fracture surfaces were relatively smooth and revealed well developed and uniformly distributed veinal pattern. The dynamically loaded specimens, on the other hand, fractured into several fragments with relatively rough fracture surfaces containing nonuniformly distributed and partially developed veinal patterns. Evidence of melting in the form of \u27liquid bubbles\u27 was also observed along the cracks on the fracture surfaces of the specimens subjected to high strain-rate loading. A comparison of the mechanical response of Vitreloy-1 with other bulk metallic glass systems is also presented. © 2002 Elsevier Science B.V. All rights reserved

Mechanical behavior of tungsten preform reinforced bulk metallic glass composites

Quasistatic and dynamic compression tests were conducted on four tungsten preform reinforced Vit105 (Zr52.5Ti5 Cu17.9Ni14.6Al10) and Vit106 (Zr57Nb5Cu15.4Ni12.6 Al10) metallic glass composites. All the composites exhibited large plastic strain under both quasistatic and dynamic compression. In general, the dynamic loading resulted in higher failure stress than the quasistatic loading. The deformation behavior was found to be dominated by the ductile W phase. Microscopic observation of the deformed and fractured specimens revealed shear banding in the glassy phase, cracking along the particle boundaries and severe deformation of W particles. It is also found that the processing methods have strong influence on the mechanical behavior of the composites even when they have the same matrix and the same volume fractions of the reinforcement. © 2005 Elsevier B.V. All rights reserved

Mechanical behavior of bulk (ZrHf)TiCuNiAl amorphous alloys

The thermodynamic and mechanical behavior of bulk (ZrHf)TiCuNiAl amorphous alloys was discussed. It was postulated that the observed strengthening might result from the microstructural changes with addition of Hf in place of Zr. The results showed that crystallization and glass transition temperatures, hardness and modulus increased with an increase in Hf content

Evolution of Microstructure and Mechanical Properties of Mg-6Al Alloy Processed by Differential Speed Rolling upon Post-Annealing Treatment

Magnesium-6 wt.% aluminum (Mg-6Al) alloy plates with a 6-millimeter thickness were processed from an initial 12-millimeter thickness by differential speed rolling (DSR), with a 0.76-millimeter thickness reduction per pass using a speed ratio of 2, preheating temperature of 315 °C, and roll temperature of 265 °C. The effects of annealing temperature of 250, 275, and 300 °C with a corresponding holding time of 15 min on the microstructure, texture, and mechanical properties were investigated. Key results show that dynamic recrystallization (DRX) occurred during the roll processing, resulting in a greatly reduced grain size. In addition, the basal pole of the as-rolled plate was inclined to the rolling direction (RD) by ~20°, due to the shear strain introduced during DSR. Subsequent annealing caused grain growth, eliminated the basal pole inclination towards the RD, and slightly increased the pole intensity. Compared with the as-rolled plate, the average of the ultimate tensile strength (UTS) and the yield strength (YS) of the annealed plates decreased, while the average elongation at fracture (εf) increased. With the annealing temperature of 275 °C, the plate achieved a good combination of mechanical properties with UTS, YS, and εf being 292.1 MPa, 185.0 MPa, and 24.9%, respectively. These results suggest that post-roll annealing is an effective way to improve the mechanical response of this Mg alloy processed by DSR