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Metalurgia INTERNATIONAL (magazine set-up
in 1995) English version,
published by romanian metallurgical
foundation Honorary president
of scientific
publishing house f.m.r. Dr. ec. Lepădatu v. gheorghe
vol. XII
(2007)
no.5 romanian metallurgical
foundation Scientific publishing
house |
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Honourary
Staff (in alphabetical order) bensabra hakim
(algeria), BORDEA MARIUS, chabour salem
(algeria), gencang yang
(china), R.
S. HOUK (S.U.A.), I. IMRI (TECHNICAL
UNIVERSITY OF KOICE,
SLOVAK REPUBLIC), pușici miho (Slovenia), roșescu gheorghe
(grecia), roxana ruxandra
(california), w.m. nicola
(tri. state university angola, indiana, s.u.a.), xianqing you (china) |
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editorial
board : Prof. colan horia Ph. D., member of Romanian Academy of
Technical Sciences Prof. Coșmeleață georgeta Ph. D. Prof. Elena drăgulănescu Ph. D., Catedra
GDGI, Aerospatial Engineering Faculty,
Bucharest Politechnical University Prof.
Dumitrescu Constantin Ph. D., deputy member of
Romanian Academy of Technical Science Prof. French David Ph. D., CSIRO Energy Technology, Australia Prof. Gălușcă Dan-Gelu Ph. D. Prof.
Mihaela Grigore Ph. D., University of New
South Wales, Sydney, Australia Prof. Lawson Cristopher Ph. D., Copenhague Technical Institute, Denmark Prof. Nicolae Avram Ph. D. Prof. Maria Nicolae Ph. D. Prof.
doc. Oprea Florea Ph. D., member of Romanian
Academy of Technical Sciences Prof.
Veena Sahajwalla Ph. D., University of New South Wales, Sydney, Australia Prof. Sakurovs Richard Ph. D.,
CSIRO Energy Technology, Australia Prof. Salvo Luc Ph. D., Grenoble National Politechnical
Institute, France Prof. Saiter Jean-Marc Ph. D., Rouen University, France Prof. Scorțea Costin Ph. D. Prof. Simiti Ioan Vida Ph. D. Prof.
Sofroni Laurenție Ph. D., member of
Romanian Academy of Technical Sciences Prof. Șaban Rami Ph. D., Dean of Materials Science Faculty, Bucharest
Politechnical University Prof. ȘTEFĂNESCU DORU Ph. D, Ohio State University Columbus, S.U.A. advisory board : Prof. bejan Mircea Ph. D Prof. cănănău nicolae Ph. D Prof. hepuț teodor Ph. D Prof. Miloșan Ioan Ph.
D. Prof. Doina Răducanu Ph. D Prof. samoilă Corneliu
Ph. D Prof. SOFONEA GALAgTION
Ph. D Prof. VARGA
BELA Ph. D Managing Director: Editor-in-chief: Professor Scorțea
Costin Ph. D. Manager Scientific Publishing House F.M.R.: eng. Florentina
Brândușa Scorțea |
Contents Issn 1582 2214 Agop Maricel, VIZUREANU Petrică, Liliana CHICOS, M. VASILICA, ABACIOAIE D., Ioannou P. D.: Hydrodinamic model
of scale relativity theory
for nanomaterials (IV). Fractal patterns
in discharges plasmas
5 Alupei - Cojocariu Ovidiu, Semenescu Augustin: Mathematic model for the direct cold extrusion process
... 15 Teisanu on pressurized
gas utilization for cooling the welded joints in austenitic stainless steel
.. 23 PARALIKA
Maria, CALEA Gheorghe, PLESCA Marcel,
NICOLAE Avram, CALEA Gh.Gheorghe, Menadil Hazel: Les qualities des
couches supereficielles ceramiques
31 Ana - Luciana
RUS, TINTELECAN Marius: Commercial aluminium alloy ..................
37 MILOSAN Ioan: Aspects
about the mathematical modelings
results of A.S.G. cast iron .. 43 ? FOSECO
Turbostop system reference list
I-II ? congresses
.................
..
.......... III
- VIII ? New books,
published by romanian metallurgical
foundation
.
........
...... IX - X |
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abstract
metalurgia International 5/2007
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D.C.: 66.015.24 Agop Maricel, VIZUREANU Petrică, Liliana CHICOS, M. VASILICA, ABACIOAIE D., Ioannou P. D.: Hydrodinamic model of scale
relativity theory for nanomaterials (IV). Fractal patterns in discharges plasmas Metalurgia International (vol. XII), no.5, 2007,
p. 5 Using a set of coupled equations for concentrations,
one shows that the self-organization of the two discharge plasmas interface
in the form of double layer or multiple layers is a fractal process (the
equal ambipolar diffusion curves are Kochs type). These structures are
projections of a higher dimensional fractal. Some applications of the model
are also given (improved confinement of neon plasma inside a high-TC
superconducting tube, multiple DLs). Key words: plastic deformation,
mathematical model of direct extrusion, non-linear differential equation Alupei - Cojocariu
Ovidiu, Semenescu Augustin:
Mathematic model for the direct cold extrusion process Metalurgia International (vol. XII), no.5, 2007,
p. 15 The direct extrusion of parts is a wordwide spreded
fabrication methode that involve a cold, mid-hot or hot volume deformation of
a raw worpiece thorugh a die. The deforming process is described through
several formulas that predict the overall pressure and force needed to
initiate and performing the deformation. Using a new mathematical model of
the deformation was developed a new simulation tool that computes the needed
forces through discrete integration. The mathematical model is represented as
a non-linear second degree differential equation, both in description of
the die profile and
for the plastic deformation characteristics of the
extruded material. Experimental approaches shows a good coverage of the
predicted responses over a choosed experimental field tested in the case of
direct extrusion of steel workpieces. A comparative approach is presented
related with the use os other known formulas that describe the direct
extrusion. D.C.: 537 Teisanu Florin, Sontea Sever: Researches on pressurized gas utilization for
cooling the welded joints in austenitic stainless steel Metalurgia International (vol. XII), no.5, 2007,
p. 23 The researches have been focused on
combining two effects beneficial to the achievement of welded joints made of austenitic stainless
steel in the
construction of some power transformer-type products. The aim was to
limit the formation of δ ferrite, constituent affecting the amagnetism
of welding seams, during the process of smelting solidification,. On the
other hand, it was obtained the removal of the gases released by the electric
arc (noxious emissions), very intensely distributed within the working
environment, which by the effect of forced cooling are adsorbed and diluted
in the air jet, leading to the improvement of the conditions from the working
environment. The cooling was carried out by an ecological process, using the
flow of cold air produced by a pneumatic generator. D.C.: 621.791 PARALIKA Maria, CALEA Gheorghe, PLESCA Marcel,
NICOLAE Avram, CALEA Gh.Gheorghe, Menadil Hazel: Les qualites des couches supereficielles ceramiques Metalurgia
International (vol. XII), no.5, 2007, p. 31 Le but principal du
processus de production et la réalisation des produits finis de qualité dans
des conditions de prix avantageuse. La qualité d'un produit est définie comme
l'ensemble des ses caractéristiques qui détermine le degré dans lequel le
produit correspond au but fonctionnel a qui il a été destiné, ça veut dire
pour satisfaire les besoins de l'économie de marche et du consomme individuel. |
Key words: 2024 aluminium alloy, superplasticity,
thermomechanical processing, strain rate, strain rate sensitivity exponent Ana - Luciana
RUS, TINTELECAN Marius: Commercial aluminium alloy Metalurgia International (vol. XII), no.5, 2007,
p. 37 In the recent years, there has been
a rapid growth in interest of superplastic aluminium alloys. This interest
has been brought about by the broad spectrum of opportunities for application
of these materials in aerospace industry. The paper reviews the aluminium
alloys, the superplastic properties of these, and the superplastic potential
of an 2024 aluminium alloy. Fine stable microstructures can be developed by
thermomechanical processing of commercial aluminium alloy. The material studied in this work is the commercial
aluminium alloy 2024-T3 received in the form of extruded bar with a diameter
of 22 mm, produced by S.C. ALPROM S.A. A special thermomechanical processing was developed
for this alloy to obtain a fine structure before superplastic testing. The
specimens from a received material with length of 60 mm and diameter of 22
mm, were homogenized at 5000C for 8 hour, reduced by hot rolling
at 440ś4800C to 7 mm strip thickness and water quenched. Then the
samples were cold rolled to 3 mm thickness. The specimens were fast heated up
to high temperature (4800C), soaked for 10-15 minutes and then
fast quenched in water followed by 30 minutes soaked at 3500C in
order to make fine-grained structure stable.
Constant strain rate tests were performed to characterise the
superplastic behaviour of this alloy. Tensile tests were conducted on a
testing equipment that was interfaced with a computer to provide complet
control of the strain rate. All tests were performed in the temperature range of
450ś4800C and in the strain rate range of 8x10-4ś2.5x10-3s-1.
Elongations to failure in excess of 200% for the fine grained 2024 Al alloy
can be obtained at the temperature of 4600C, in the strain rate
range of 8x10-4ś1.5x10-3 s-1. A
maximum elongation of 245.5% was measured in the superplastic conditions of
4600C and the strain rate 1x10-3 s-1 . The microstructure of the as-received bar shows a
structure consisting of large grains with the average grain size of 36ś40
μm. In contrast, the processing microstructure consists of echiaxed
recrystallized fine grains with particles present at the grain boundaries and
the grain interiors. The average grain size at the center of the processed
region was found to be 5ś8 μm. The strain rate sensitivity value obtained for the
2024 aluminium alloy thermomechanical processed is 0.3462 at the temperature
of 4600C in the strain range of 8x10-4 ś1.5x10-3 s-1. Key word: Mathematical modeling, regression equation,
mechanical properties, S.G. Cast Iron MILOSAN Ioan: Aspects
about the mathematical modelings results of A.S.G. cast iron Metalurgia International (vol. XII), no.5, 2007,
p. 43 The paper contains a study about computer use in graphical and
mathematical processing of the results of some researchers about Ni-Cu-Cr
alloyed, ferrito-bainitic, S.G. cast iron. It is pointed out the influence of
some metallurgical factors on the phase transformation and properties in the
studied cast iron. |
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1. The METALURGIA INTERNATIONAL magazine
receives manuscripts of papers including basic scientific research and industrial research in the following fields:
metallurgy, materials science and engineering and different relating
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