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© 2007 editura
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copyright of parts from this publication is allowed with the written
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Brânduşa Scorţea Assistant-secretary Editura Ştiinţifică F.M.R. Anca Ion |
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
(2007)
no.9 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. IMRIŠ (TECHNICAL
UNIVERSITY OF KOŠICE,
SLOVAK REPUBLIC), puşici miho (Slovenia),
roşescu 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. Coşmeleaţă georgeta Ph. D. Prof. Elena drăgulănescu Ph. D., Catedra GDGI, Aerospatial
Engineering Faculty, Bucharest Politechnical University, Romania Prof.
Dumitrescu Constantin Ph. D., deputy member of
Romanian Academy of Technical Science Prof. French David Ph. D., CSIRO Energy Technology, Australia Prof. Găluşcă 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 Dr. Ec. Lepădatu
V.Gheorghe, Demetrius Cantemir Christian University,
Bucharest, Romania 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. Simiti Ioan Vida Ph. D. Prof.
Sofroni Laurenţie Ph. D., member of
Romanian Academy of Technical Sciences Prof. Şaban Rami Ph. D., Dean of
Materials Science Faculty, Bucharest Politechnical University Prof. ŞTEFĂNESCU DORU Ph. D, Ohio State University Columbus, S.U.A. Prof.VASIU Teodor Ph. D., Faculty of „Engineering” in advisory board : Prof. erika ardelean Ph. D Prof. bejan Mircea Ph. D Prof. cănănău nicolae Ph. D Prof. hepuţ teodor Ph. D Prof. miloşan ioan Ph. D Prof. Doina Răducanu Ph. D Prof. rusu nicolae Ph. D Prof. samoilă Corneliu Ph. D prof. semenescu
augustin ph. d Prof. SOFONEA GALAgTION
Ph. D Prof. VARGA
BELA Ph. D Managing Director: Editor-in-chief: Prof. Scorţea Costin Ph. D. |
Contents Issn 1582 – 2214
materials science field .…5 - 32 Khaled M. Ibrahim, Mohamed M. Mourad, Mervat M.
Ibrahim, Adel A. Nofal:
Austempering of Thin Wall
Ductile Iron Castings ……..….. 5 Georgeta Predeanu: Structural properties developed on
brown coals by physical activation ………………………………….....
16 KISS Imre: Laboratory
experiments regarding the durability in exploitation of the hot
rolling mill cylinders ……………………………..…. 20 X X X Ghionea Florian: General consideration about a smoothing
process in urban transport …..... 28
in metallurgy.......................... 33
- 38 Lepădatu V.
Gheorghe: The target
costing …….. 33 ? FOSECO
Turbostop system – reference list… I-II ? Congresses
............…..………………..…...... III-IV ? New books,
published by romanian metallurgical
foundation……………….……..…….....…..... V-VI |
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abstract
metalurgia International 9/2007
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Key words: ADI, thin-wall, austempering treatment, mechanical
properties, casting design. Khaled M. Ibrahim, Mohamed M. Mourad, Mervat M.
Ibrahim, Adel A. Nofal:
Austempering of Thin Wall Ductile Iron Castings Metalurgia International (vol. XII), no.9, 2007,
p. 5 Production of thin wall austempered ductile iron
(TWADI) components can have strength-to-density and elastic-to-density ratios
that approach those of cast aluminum, making it theoretically possible to
apply ADI in high strength light weight parts. Therefore, development of thin
wall ADI technology is essential to permit designers for energy consuming
equipment to choose the most appropriate material based on material
properties, and not solely on weight or density. In the present work, ductile
iron castings with different thicknesses of 2, 4, 6 and 8 mm were cast with
an appreciate casting design to assure good mold filling. Short term
austempering treatment process was used to obtain thin wall ADI castings. The
samples of 2 and 4 mm thickness were austenitized at 900 °C for 30 minutes
followed by holding at 350 °C and 400 °C for 10 minutes for each temperature.
While, the samples of 6 and 8 mm wall thickness were austenitized at 900 °C
for 30 minutes and followed by holding at 350 °C and 400 °C for 30 minutes.
The microstructure of TWADI austempered at 350 °C showed finer structure than
that austempered at 400 °C. Tensile strength, hardness and wear resistance
increased with decreasing casting wall thickness austempered at 350 °C due to
the structure refinement effect and decreasing the volume fraction of
retained structure in matrix. The minimum wear rate was obtained for 2 mm
casting wall thickness austempered at 350 °C.
D.C.: 669. Georgeta Predeanu: Structural properties developed on brown coals by physical activation Metalurgia International (vol. XII), no.9, 2007,
p. 16 The experiments have been carried out on two Romanian
activated brown coals. The trials proved that the nature of precursor has a
strong influence on the structure and properties of the activated carbons
(AC). At the same time, the product’s adsorption capacity is determined by
the manufacturing conditions, performed in our case on laboratory scale. The
experimental conditions used in this work are included, and the comments
concerning the influence of different parameters on the AC specific surface
area, as: coal rank, grain size, burn-off, carbonization and activation
temperature. The AC from the brown coal A posse’s higher volume of pores than
in case of brown coal B, with a prevalence of micropores and large BET
surface area (320 m2/g). Key
words: hot rolling, iron cylinders,
durability in exploitation, thermal fatigue KISS Imre: Laboratory
experiments regarding the durability in exploitation of the hot rolling mill
cylinders Metalurgia International (vol. XII), no.9, 2007, p. 20 The research
on rolling mills cylinders durability in |
exploitation
experimentally defines an important chapter from the thermal fatigue of the
organs of machines in the movement of rotation, in variable temperature
mediums, and the mathematical molding establishes a methodology for the
determination of the technological parameters values, for which a mechanical
characteristic (the hardness) has the desirable values. The technological manufacturing process of the
rolling mills cylinders, as well as the quality of material used in
manufacturing them, can have a different influence upon
the quality and
the safety in
the exploitation. Our proposal approaches the issue of quality
assurance of the rolling mills cylinders, from the viewpoint of the quality
of materials, which feature can cause duration and safety in exploitation. The experimented durability research, as well as the
optimization of the manufacturing technology, allows the conclusion of direct
results for the rolls. The beneficiaries of these results are the unit in
which the rolls are manufactured, as well as the unit that exploits them. The
research on the durability in exploitation of hot rolling mill cylinders
represents an important scientific and economical issue. The study represents
a detailed approach of the influence of some technological factors on the
durability in exploitation of rolling mill iron cylinders and suggests
solutions meant to increase the durability of the rolls in exploitation. Key
words: smoothing process in urban transport Ghionea Florian: General consideration about a smoothing process in urban transport Metalurgia International (vol. XII), no.9, 2007,
p. 28 In
theory, in passanger urban transport system, the level of the offer must be
the same with the level of the demand, and this is a consequence of
economical rules. It is available another (extreme) alternative: one can
maintain a constant standard of the vehicles park in lines, indifferent of
the demand aspect. But, there is a middle way too: sometimes accepting
deviations from the preset states, other times forcing the system to put on
the ideal itinerary, it can be determined if the goal is to permanently
maximize the entire operation utility function. The present paper shows that
it is possible to interpretation some of the economical rules in function of
type of the objectives (tactical or operational) for a exploitation problem:
the “zero paths”. One of the explanations that assimilate the theory of
equilibrium between demand and offer to the field work could result from
analyzing the referred phenomenon : from static point of view, the
equilibrium theory is obviously valid, but from dynamic point of view,
operational maintaining of the equilibrium is inadequate. Key words: target costs, direct costs, indirect costs, price,
benefit, cost Lepădatu V.
Gheorghe: The target
costing Metalurgia
International (vol. XII), no.9, 2007, p. 33 The method of target costing represents a strategic managerial approach for
products, in which of cost carriers are analysed during the entire life cycle
and particularly during the conception stage. |
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