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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.6 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: Editor-in-chief: Professor Scorţea Costin Ph. D. editorial board: Prof. dr. eng. bejan Mircea Prof. dr. eng. cănănău nicolae Prof. dr. eng. GĂLUŞCĂ DAN GELU Prof. dr. eng. hepuţ teodor Prof. dr. eng. IONIŢĂ GHEORGHE Conf.dr. eng. TODERIŢA NEMEŞ Prof. dr. eng. MARIA NICOLAE Prof. dr. eng. Ripoşan Iulian 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 Stela Constantinescu: Research on the optimum heat treatment for the low alloyed steels used at high temperatures ………. 3 GHIMBĂŞEANU Ioan: Calculation method of a numerical regulator for controlling a endo-typed controlled atmosphere in a carburization process …………………………………………. 7 Ciobanu Ioan, Munteanu Sorin Ion, Crişan Aurel: finite differences mathematical model for the macrosolidification of parts cast from hypoeutectic cast iron ………………….….. 13 Florentina Potecaşu, Potecaşu Octavian, Alexandru PetricĂ: Properties of extruded semi-products of superficial oxidated lead powder ………………………………………… 26 Chichernea Florin: Comparative study on static breaking of cast steel part shrink heads-forth chapter …………………….…. 33 Munteanu Sorin Ion, Ciobanu Ioan, Crişan Aurel: The macro-solidification simulation for a bar with U section cast in eutectic cast iron …………………………………………..… 38 ? Press release ……………..…………………….……...................... I – II ? International events …………….…………………………. III ª Invitation ……………………………………………... III ª Industry events …………………………...……. III - VII ª The world’s leading competence centre …………….VII ª Alta 2005 conferences …………….………………....VIII ª Trade shows thematic & chronological list ……..…VIII ? New books, published by romanian metallurgical foundation… IX-X

abstract

metalurgia International 6/2005

D.C.: 621.785 Stela Constantinescu: Research on the optimum heat treatment for the low alloyed steels used at high temperatures Metalurgia International (vol. X), no.6, 2005, p. 3 To determine the final optimum heat treatment, normalization- annealing and quenching-annealing of the thick RRC plates use was made of a methodology which implies to establish the temperature here resilience is lower than the min admissible value , I e 54 J under the following states: normalization- annealing , quenching-annealing , normalization - annealing - detensioning, quenching-annealing – detensioning , normalization- annealing – detensioning- sensibilisation, quenching-annealing – detensioning- sensibilisation . The measurements have shown an increase in the transition temperature as the material undergoes successive thermal operations, the phenomenon becoming quite obvious for the state normalization- annealing The chemical equipment working at high temperatures are made from easily welding carbon or low alloyed steels of Cr and Mo. The steel is alloyed with 1,25% Cr and 0 5% Mo and is usually called RRC on the home market. D.C.: 66.046.562.2; 621.78.062.3 GHIMBĂŞEANU Ioan: Calculation method of a numerical regulator for controlling a endo-typed controlled atmosphere in a carburization process Metalurgia International (vol. X), no.6, 2005, p. 7 The paper describes several research studies on the identification and the control of ENDO-typed controlled atmosphere in a carburization process. Combining the calculation methods of the regulators and the identification techniques of the process models, a rigurous procedure as well as a calculation performance will be obtained. The calculation and the adjustment of different types of regulators require a sound knowledge of the discret parametric model of the process to adjust D.C.: 669.15-196.52; 621.746.628 Keywords: mathematical model, solidification, hypoeutectic cast iron Ciobanu Ioan, Munteanu Sorin Ion, Crişan Aurel: finite differences mathematical model for the macrosolidification of parts cast from hypoeutectic cast iron Metalurgia International (vol. X), no.6, 2005, p. 13 The paper presents a model and a software for the solidification of parts cast in hypoeutectic cast iron. There are presented the hypothesis that lay on the base of the realised mathematical model. The model uses the finite differences method and is initially conceived in 1D, following to be extended to 2D and 3D. The mathematical model starts from thermal balance equation for an elementary layer of xi thickness and an elementary time interval Dt. In the case of hypoeutectic cast iron there were stand out 16 situations for which it was necessary to detail the thermal balance equation. There are presented the mathematical equations that form the mathematical model and their usage in the software. There are presented two, the software structure and the possibilities of

using this software during the research about the solidification of parts cast from hypoeutectic alloys. D.C.: 621.762 Florentina Potecaşu, Potecaşu Octavian, Alexandru PetricĂ: Properties of extruded semi-products of superficial oxidated lead powder Metalurgia International (vol. X), no.6, 2005, p. 26 The purpose of this research paper is to make semi- products from controlled oxidation lead powder in an attempt to underline the influence of the powder granulation and the particles in the partially oxidized powder mixture on the mechanical, chemical and electrical properties, the structures and phenomena occurring during the plastic deformation process. Two research approaches are presented in the paper. Oxide dispersion into the metallic matrix was achieved by deforming the sinters through extrusion. During extrusion, the particles are compelled to pass through the matrix calibration zone and consequently they are considerably deformed. As an effect of this deformation, the particles of fragile oxide which cover the lead powder particles are crashed and carried away to the material flowing through the matrix longitudinally on the extruded semi product. The experiments showed that these products had improved properties in terms of mechanical resistance, corrosion resistance in an acid medium and electrical conductivity. Therefore, it is recommended to use these materials for making support gratings for the lead accumulators as an alternative to the present day technologies in order to obtain longer service life. D.C.: 621.746.464 Keywords: modelling, the static break, running, feeding, cast steel Chichernea Florin: Comparative study on static breaking of cast steel part shrink heads-forth chapter Metalurgia International (vol. X), no.6, 2005, p. 33 In the laboratories of the Materials Science and Engineering Faculty of the Transilvania University of Brasov a number of theoretical and experimental studies have been conducted on the 3D – modelling of part casting with gatings and shrink heads, as well as on the modelling of breaking generating strains. D.C.: 669.15-196.53 Keywords: mathematical model, solidification, simulation Munteanu Sorin Ion, Ciobanu Ioan, Crişan Aurel: The macro-solidification simulation for a bar with U section cast in eutectic cast iron Metalurgia International (vol.X), no.6, 2005, p. 38 The paper presents a 2D mathematical model, based on finite differences method and a software created by authors, to simulate the solidification of castings with translation symmetry. There are presented the hypotheses that are on the basis of the model. There are presented too the application conditions of the program to study the solidification of the profiles with U20x20 section, as well as the parameters that can be analysed using this program.