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Abstract

Al2Cu phase has been obtained by melting pure metals in the electric arc furnace. It has been found that the intermetallic phase undergoes selective corrosion in the H3PO4 aqueous solutions. Aluminium is dissolved, the surface becomes porous and enriched with copper. The corrosion rate equals to 371 ± 17 g·m–2·day–1 (aerated solution) and 284 ± 9 g·m–2·day–1 (deaerated solution). The surface of Al2Cu phase after selective corrosion was characterised by using electrochemical impedance spectroscopy. It was found that the surface area of the specimens increases with temperature due to higher corrosion rate and is between 2137 and 3896 cm2.

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Authors and Affiliations

P. Kwolek
A. Gradzik
D. Szeliga
B. Kościelniak
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Abstract

The analysis of influence of mould withdrawal rate on the solidification process of CMSX-4 single crystal castings produced by Bridgman

method was presented in this paper. The predicted values of temperature gradient, solidification and cooling rate, were determined at the

longitudinal section of casting blade withdrawn at rate from 1 to 6mm/min using ProCAST software. It was found that the increase of

withdrawal rate of ceramic mould results in the decrease of temperature gradient and the growth of cooling rate, along blade height. Based

on results of solidification parameter G/R (temperature gradient/solidification rate), maximum withdrawal rate of ceramic mould

(3.5 mm/min), which ensures lower susceptibility to formation process of new grain defects in single crystal, was established. It was

proved that these defects can be formed in the bottom part of casting at withdrawal rate of 4 mm/min. The increase of withdrawal rate to 5

and 6 mm/min results in additional growth of susceptibility of defects formation along the whole height of airfoil.

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Authors and Affiliations

J. Sieniawski
D. Szeliga
K. Kubiak
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Abstract

In hot forging process, tool life is an important factor which influences the economy of production. Wear mechanisms in these processes are dependent on each other, so modeling of them is a difficult problem. The present research is focused on development of a hybrid tool wear model for hot forging processes and evaluation of adding adhesive mechanism component to this model. Although adhesive wear is dominant in cases, in which sliding distances are large, there is a group of hot forging processes, in which adhesion is an important factor in specific tool parts. In the paper, a proposed hybrid tool wear model has been described and various adhesive wear models have been reviewed. The feasible model has been chosen, adapted and implemented. It has been shown that adding adhesive wear model increases predictive capabilities of the global hybrid tool wear model as far as characteristic hot forging processes is considered.

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Authors and Affiliations

M. Wilkus
Ł. Rauch
D. Szeliga
M. Pietrzyk

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