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Abstrakt

The paper presents results of examination of material parameters of cast iron with structure obtained under rapid resolidification conditions carried out by means of the nanoindentation method.

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Autorzy i Afiliacje

A. Trytek
M. Tupaj
M. Mróz
W. Orłowicz

Abstrakt

Explosion protection is of particular importance for safety as explosions also endanger the health of workers due to the uncontrolled effects of flames and pressure, the presence of harmful reaction products and the consumption of oxygen in the ambient air breathed by workers. CuAlBe alloy is proposed as a solution for mechanical actuators such as gears that work in environments with possible explosive atmosphere. Made of CuBe master alloy and pure aluminum in a induction furnace the material present large grains in melted state. After the hot rolling (heated 600s at 900°C) of the ingots small variation of chemical composition was observed based on the oxidation of the material, appearance of small cracks on the edges and a preferential orientation of the grains along the lamination direction. Scanning electron microscopy (SEM) was used to characterize the microstructural states of CuAlBe as laminated and heat treated states.
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Autorzy i Afiliacje

G.R. Chelariu
1
ORCID: ORCID
N. Cimpoeșu
1
ORCID: ORCID
P. Paraschiv
1
ORCID: ORCID
B.A. Prisecariu
2
ORCID: ORCID
I. Rusu
1
ORCID: ORCID
I. Știrbu
1
ORCID: ORCID
G.I. Sandu
1
ORCID: ORCID
M. Benchea
3
ORCID: ORCID
C. Bejinariu
1
ORCID: ORCID

  1. Gheorghe Asachi University of Iasi, Faculty of Materials Science and Engineering, 43 Dimitrie Mangeron str., 700050, Iasi
  2. “Grigore T. Popa” University of Medicine and Pharmacy, Iasi, Romania
  3. Gheorghe Asachi University of Iasi, Mechanica l Faculty, 43 Dimitrie Mangeron str., 700050, Iasi

Abstrakt

Residual stress has a great influence on the metal, but it is difficult to measure at small area using a general method. Residual stress calculations using the Vickers indentation can solve this problem. In this paper, a numerical simulation has been made for the residual stress measurement method of metal material deformed by high-speed impact. Then, the stress-strain curve at the high-speed deformation was confirmed through actual experiments, and the residual stresses generated thereafter were calculated by the Vickers indenter method. A Vickers indentation analysis under the same conditions was performed at the position where a residual stress of about 169.39 MPa was generated. Experiments were carried out and high speed impact was applied to the specimen to generate residual stress. The obtained results indicate that it is possible to identify residual stresses in various metals with various shapes through Vickers indentation measurements, and to use them for process and quality control.

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Autorzy i Afiliacje

Changho Jung
Moon G. Lee
Yongho Jeon

Abstrakt

The small artificial surface defects in the coarse-grain steel are studied. The size of the used defects is smaller than the most relevant microstructural unit of steel, i.e. the average grain size. The samples of coarse-grain steel are prepared using a welding thermal-cycle simulator and a laboratory furnace. The defects are made by indenting with a Vickers pyramid. One of the final results of the defect making is the existence of local residual stresses. The influence of residual stresses on the crack initiation from those artificial defects is discussed in the article.

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Autorzy i Afiliacje

Vladimir Gliha
Volodymyr Hutsaylyuk
Lucjan Śnieżek
Tomaz Vuherer

Abstrakt

The cooling rate is one of the main tools available to the process engineer by means of which it is possible to influence the crystallisation

process. Imposing a desired microstructure on a casting as early as in the casting solidification phase widens significantly the scope of

technological options at disposal in the process of aluminium-silicon alloy parts design and application. By changing the cooling rate it is

possible to influence the course of the crystallisation process and thus also the material properties of individual microstructure

components. In the study reported in this paper it has been found that the increase of cooling rate within the range of solidification

temperatures of a complex aluminium-silicon alloy resulted in a decrease of values of the instrumented indentation hardness (HIT) and the

instrumented indentation elastic modulus (EIT) characterising the intermetallic phase occurring in the form of polygons, rich in aluminium,

iron, silicon, manganese, and chromium, containing also copper, nickel, and vanadium. Increased cooling rate resulted in supersaturation

of the matrix with alloying elements.

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Autorzy i Afiliacje

A. Trytek
M. Tupaj
M. Mróz
A.W. Orłowicz
O. Markowska

Abstrakt

This study attempted to manufacture an Y2O3 ceramic coating layer on a ceramic (AlN) substrate using aerosol deposition (AD) and investigated its macroscopic properties. Pure Y2O3 powder with a polygonal shape and average size of 5.0 μm was used as initial feedstock. Using aerosol deposition with suitable process conditions, an Y2O3 coating layer was successfully fabricated on aluminum nitride (AIN). The thickness of the manufactured coating layer was approximately 10 mm. The coating layer consisted of Y2O3 phase identical to that in the initial powder, and no additional oxides were identified. In regard to the roughness of the Y2O3 coating layer, the average roughness (Ra) measured 1.32 μm, indicating that the surface roughness was relatively even compared to the initial powder size (5 μm). Mechanical properties of the Y2O3 coating layer were measured using nano indentation equipment, and the indentation modulus of the Y2O3 coating layer fabricated by aerosol deposition measured 136.5 GPa. The interface of the coating layer was observed using TEM, and the deposition mechanism of the Y2O3 coating layer manufactured by aerosol deposition was also discussed.

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Autorzy i Afiliacje

D.-Y. Wi
G.-S. Ham
S.-H. Kim
K.-A. Lee

Abstrakt

New computational procedures developed within the framework of international research projects „Grispe” and „Grispe Plus” are briefly presented and characterised here. Considered algorithms pertain to the verification of bearing capacity and serviceability of selected bearing structure components erected with especially shaped thinwalled sheet metal panels. Structural components of this type are so far rather absent from the codes, and as a result the unequivocal design requirements have not been developed for them. Key problems related to the detailed analysis of the following element classes: steel decks with embossments, indentations and/or outwards stiffeners; liner trays; corrugated sheeting; curved profiles; cladding and roof profile assemblies; perforated and holed profiles; external interlocking planks and their assemblies are indicated in the text. The procedures formulated as a part of the projects indicated above have been delivered to CEN as an official proposal of amendments and/or additions submitted for introduction to the new generation of Eurocodes currently under preparation, and especially as an extension to the code EN 1993-1-3.

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Autorzy i Afiliacje

M. Maslak
M. Pazdanowski

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