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Metalurgia INTERNATIONAL English version, published by romanian metallurgical foundation Honorary president of scientific publishing house f.m.r. Dr. ec. Lepădatu v. gheorghe vol. X (2005) no.1 romanian metallurgical foundation Scientific publishing house

romanian metallurgical foundation Scientific publishing house scientific board staff Professor NICOLAE AVRAM Ph. D. professor Scorţea Costin Ph. D Managing Director: Professor Scorţea Costin Ph. D. Editor-in-chief: Professor Nicolae Avram Ph. D. Professor Maria Nicolae Ph. D editorial board: Prof. dr. eng. bejan Mircea Prof. dr. eng. bunea Daniel Prof. dr. eng. cănănău nicolae Prof. dr. eng. GEORGETA COŞMELEAŢĂ Prof. dr. eng. CIUCĂ ION Prof. dr. eng. gaba aurel Prof. dr. eng. GĂLUŞCĂ DAN GELU Prof. dr. eng. hepuţ teodor Prof. dr. eng. IONIŢĂ GHEORGHE Prof. dr. eng. mănescu tiberiu Conf. univ. dr. ing. TODERIŢA NEMEŞ Prof. dr. eng. samoilă Corneliu Prof. dr. eng. SCORŢEA COSTIN Prof. dr. eng. SIMITI IOAN VIDA Prof. dr. eng. SOFONEA GALAFTION Prof. dr. eng. Şaban Rami Manager Scientific Publishing House F.M.R.: eng. Florentina Brânduşa Scorţea

Contents Issn 1582 – 2214 Ştefănoiu Radu, Geantă Victor: Experimental researches regarding the dimensions of the gas bubbles formed at inert gas injection into the liquid steel …………………..……..3 Felicia Bratu, Neacsu Marian:: Effect of the fretting parameters open-circuit potential of AS7G06 aluminium alloy ..….10 Erika Ardelean: The influence of technological work parameters on primary solidification of semi-finished parts obtained by continuous casting …………………………………….….15 Beatrice Tudor: Researches concerning the corrosion behavior of Al alloy …………………………………………………….22 Cojocaru V. Dănuţ: Ball-milling synthesis of nanostructured hitperm alloys ………………………..………………….29 Stanciu Sergiu, Bujoreanu gh.-Leandru, Ioniţă Iulian, Găluşcă Dan-Gelu, Munteanu Corneliu: Chemical composition effects on the thermal memory of β-type …32 Miloşan Ioan: Researches about the wear resistence of a S.G. cast iron ………………………………………………………...42 ? Press release …………...……….………………..………................I – VI ? Authors Index ……………………………………………………VII - VIII ? New books, published by romanian metallurgical foundation IX - X

abstract

metalurgia International 1/2005

D.C.: 669.184.144-7; 621.43-4 Keywords: modeling, simulation, inert gas injection, steel refining, bubble dimension Ştefănoiu Radu, Geantă Victor: Experimental researches regarding the dimensions of the gas bubbles formed at inert gas injection into the liquid steel Metalurgia International (vol. X), no.1, 2005, p. 3 The determination of the gas bubbles dimensions formed at the injection orifice is important for establishing the flow regime which takes place at the inert gas injection into a liquid steel. Also, knowing the inert gas bubbles dimensions is determinant in order to estimate the physico-chemical processes efficiency specific to inert gas refining steels. This paper presents the results of the model experimental researches regarding the inert gas bubble dimension formed inside of the ferrous metal baths at the inert gas injection through three types of injection systems. D.C.: 669.71 Felicia Bratu, Neacsu Marian:: Effect of the fretting parameters open-circuit potential of AS7G06 aluminium alloy Metalurgia International (vol. X), no.1, 2005, p. 10 The synergism wear-corrosion can produce a significant increase in the total material loss even for those materials characterized by a good corrosion resistance in absence of mechanical wear. Therefore it’s important to determinate which is the influence of the mechanical parameters on the electrochemical parameters, more exactly open-circuit potential. This work shows that an increase of the fretting normal force value conduces to a decrease of the potential mean value while the frequency influence must be correlated with the normal force variation could be more evident since the normal force increase. In these conditions an increase of the frequency is accompanied by a decrease of potential. D.C.: 621.746.628’ Erika Ardelean: The influence of technological work parameters on primary solidification of semi-finished parts obtained by continuous casting Metalurgia International (vol. X), no.1, 2005, p.15 The primary cooling, inside the mould, has a high importance in what concerns the thickness of the solidified steel crust. If the crust is too thin when coming out of the mould, under the action of the ferro-static pressure generated by the liquid steel from inside and due the own weight of the strand, the crust can force through, thus resulting the strand breaking. The paper presents a series of correlation between the casting speed (as a technological parameter) and the cooling conditions inside the mould for three different profiles of the crystallizing vessel: 240x270 mm, Ø 150 mm and Ø 180 mm.

D.C.: 620.193 Beatrice Tudor: Researches concerning the corrosion behavior of Al alloy Metalurgia International (vol. X), no.1, 2005, p.22 This report shows the electrochemical methods applied to study the aluminium alloys were: the potentiodynamic (PD) method and the electrochemical impedance spectroscopy (EIS). The measurements have been made on two alloys AlCu, samples A and C, thermally treated by quenching and aging to 150^0C It can be seen that both exolated samples have a corrosion speed lower than the uncoated samples, this being due to the barrier role played by the oxide layer formed on the samples after exolation. D.C.: 621.771 Cojocaru V. Dănuţ: Ball-milling synthesis of nanostructured hitperm alloys Metalurgia International (vol.X), no.1, 2005, p.29 Over the last decade, nanocrystalline materials were investigated for applications in magnetic devices that require soft magnetic materials (transformers, inductive devices, etc). The benefits of nanocrystalline alloys stem from their chemical and structural variations over nanometer scale which are important for developing optimal magnetic properties. High induction bulk materials, including HITPERM-type alloys, were investigated, however less attention has been paid to the stability of nanostructured materials under extreme conditions of pressure and temperature. The main aim of the present work is to study the synthesis of soft-magnetic nanostructured materials. HITPERM-type alloy powders were prepared by high-energy ball-milling. The evolution of crystallinity and grain-size during the ball-milling process was evaluated using synchrotron radiation X-ray diffraction. D.C.: 621.744 ; 669.018 Stanciu Sergiu, Bujoreanu gh.-Leandru, Ioniţă Iulian, Găluşcă Dan-Gelu, Munteanu Corneliu: Chemical composition effects on the thermal memory of β-type Metalurgia International (vol.X), no.1, 2005, p. 32 D.C.: 669.131.622 Miloşan Ioan: Researches about the wear resistence of a S.G. cast iron Metalurgia International (vol. X), no.1, 2005, p.42 The paper presents an application of classical isothermal heat treatment and the influence of some technological factors over the structure and the abrasive wear properties of a Ni-Cu low alloy S.G. cast iron. It was determined the lost weight of the samples during the test and it was approximated the wear resistance of a studied S.G. cast iron.