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1

Focus on development of quality, high pressure die casting process

Peter I., Rosso M.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

125--128

EN

In contemporary high-pressure die casting foundries, the mastery of each sequence in the production cycle is more and more important. In the paper, an example of virtual analysis of gearbox casting from Al alloy will be presented. It includes a large variety of parameters, as follows: choosing of appropriate foundry technology, calculation of computer simulation of casting process which takes into account the filling process of cold chamber and filling of cavity, model description of three phases in high-pressure die casting, flow of molten metal, solidification, formation of stress and deformations. Additionally, the optimization of cooling and heating systems will be compared with calculated volume defects, dimensions of castings and their deformations with experimentally obtained values.

2

A comparative study of Ti-Al and Ti-Nb alloys for advanced technological applications

Peter I., Rosso M., Castella C.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 73, nr 2

199--205

EN

Purpose: of this paper is to compare some properties of Ti-Al and Ti-Nb alloys to investigate on the possibility to jointly employed them industrially. Ti-Al alloys have been proposed because they present challenging characteristics for high temperature purposes and β type Ti-Nb alloy has specific mechanical properties at room temperature. Ti-Al alloys are very attractive materials and represent one of the most important materials employed for aero jet engines. The most promising alloy belonging to the above mentioned classes are predominantly based on simultaneously presence of two phases, namely γ-TiAl (gamma titanium aluminides) and α2-Ti3Al both with a fully lamellar microstructure and could replace Ni-based superalloys in some high temperature applications in aerospace and automotive industries. The most important advantages of such alloys compared to some superalloys consist in their low density correlated to their superior efficiency in service and reduced gas emission. Design/methodology/approach: The Ti-Al alloy have been produced by gravity casting, using a vibrating furnace, while the Ti-Nb alloy samples have been realized by the cold crucible levitation melting (CCLM) casting technology. Microstructural and mechanical characterization have been performed. Findings: The microstructural analysis for the Ti-Al alloy reveals a fully-lamellar microstructure with alternate plates of α2-(Ti3Al) and γ-(TiAl) plates. The grains have an average size of about 200 μm. For the Ti-Nb based alloy only a β mono-phase has been detected. This alloy has a equiaxed microstructure with an average grain dimension of about 170 μm. The Ti-Nb alloy presents a high mechanical strength while on the contrary that of the Ti-Al has been deleteriously affected by the presence of large gas porosities. Superior hardness values have been reached with Ti-Al alloy, due to the presence of hard γ-TiAl. Practical implications: The most important implication is related to the transfer toward the proper choice of the correct parameters during manufacturing. Originality/value: Investigation on the influence of the elemental composition enriched by other elements and casting processes on the defect development, the microstructural characteristics and on the mechanical behaviour of the alloys.

3

About heat treatment and properties of Duplex Stainless Steels

Rosso M., Peter I., Suani D

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 59, nr 1

26--36

EN

Purpose: of this paper is to review the effect of heat treatments and of strain hardening on microstructure and properties of superduplex stainless steels. Design/methodology/approach: Annealing and strain hardening treatments influences microstructures and properties. Findings: The characteristics and the properties of the industrially employed superduplex grade has been discussed, moreover the presence and the precipitation of sigma phase has been highlighted through ageing treatments. Research limitations/implications: : Based on the up to date achieved outcomes, it appears that a quite homogeneous and good mechanical properties can be obtained controlling the composition and the heat treatment and strain hardening parameters. Practical implications: The major implication is related to the transfer toward the proper choice of correct parameters for working the duplex grades. Originality/value: to supply deeper information with respect to those available in literature, which does not clearly indicate what amount of secondary phases existing in duplex stainless steel microstructure can be acceptable.

4

Investigation on Cobalt based alloy modified by Titanium for dental applications

Peter I., Rosso M., Toppi A., Dan I., Ghiban B.

Archives of Materials Science and Engineering

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2013

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Vol. 61, nr 2

62--68

EN

Purpose: The main goal of this study is to develop and obtain some competitive products, with high added value. In particular, the attention will be focused on the possibility to obtain a new class of Cobalt based alloy by Ti addition. Design/methodology/approach: Modification of the composition by Ti addition can increase the corrosion resistance, processing and at the same time can improve the alloy biocompatibility. Findings: Addition of these elements has a positive effect on the alloy hardness. Up to 6% of Ti or combining Ti and Zr as alloying elements there are no significant differences as hardness concerns. As corrosion resistance in a simulated oral cavity environment concerns, no significant release of metal ions was observed, the pH value and the weight loss fulfil the conditions required by the Standard ISO 10271/2011. However, the best behaviour was obtained employing CoCrMoTi6 alloy. Research limitations/implications: Based on the up to date achieved outcomes, it appears that a quite homogeneous and good mechanical properties have been obtained modifying the original alloy with 6% of Ti. The future research work will be oriented to get additional and detailed data on the biocompatibility of the alloy. Practical implications: The central issue is the valid transfer to dentistry application. Originality/value: The aim of the paper is to obtain a new class of Co based alloy by the modification of the original chemical composition.

5

Continuous casting and rolling for the manufacturing of thin Al sheets

Rosso M., Peter I.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 52, nr 2

59--66

EN

Purpose: Purpose of this paper is presenting the state-of-the-art and the mechanism of Al continuous casting process and to improve the microstructure of the Al sheets reducing the morphological differences between the surface layer and the core of the considered alloy. Design/methodology/approach: After a short illustration of some techniques which are presently employed for the production of Al alloy sheets for packaging applications, the development of the grain structure and the effect of the homegenization treatment and rolling on the microstructurural evolution has been presented and discussed. Findings: The positive effect of the homogenization treatment and rolling on the microstructure has been demonstrated. The homogenized alloy presents improved workability and machinability. Research limitations/implications: Based on the up to date achieved outcomes, it appears that homogeneous, fine microstructure and quite uniform distribution of the particles allow obtaining higher mechanical properties. The future research work will be oriented to get additional and detailed data on the performance of the alloy. Practical implications: The continuous increase of Al-based alloys in different applications involves manufacturing high integrity and superior performance components using cost-effective and safely processes. In this direction the research communities together with manufacturing industries are focusing their attention to develop new and enhanced products using innovative procedures. The central issue is the technological transfer to industry for affordable mass production. Originality/value: Obtaining a fine and homogenous microstructure for Al sheets by reducing the morphological differences between the surface layer and the core of the alloy improved mechanical performances and enhanced workability and machinability has been obtained. High performance end-product make this type of alloy very attractive for packaging material production.