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1

Evaluation of the cutting force components and the surface roughness in the milling process of micro-and nanocrystalline titanium

Habrat W., Motyka M., Topolski K., Sieniawski J.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 3

1379--1384

EN

Nanocristalline pure titanium in comparison to inicrocrystalline titanium is characterized by better mechanical properties which influence its wider usability. The aim of the research was to evaluate whether the grain size of pure titanium (micro- and nanocrystalline) has influence on the cutting force components and the surface roughness in the milling process. Models of cutting force components for both materials were prepared and differences between the results were examined. The feed rate effect on selected parameters of surface roughness after milling of micro- and nanocrystalline pure titanium was determined.

2

Elastic modulus of nanocrystalline titanium evaluated by cyclic tensile method

Topolski K., Brynk T., Garbacz H.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 4

927--934

EN

The present study is devoted to examinations of the elastic modulus with the use of the uniaxial tensile test. The commertial purity titanium Grade 2 in the two states i.e. microcrystalline (mc-Ti) and nanocrystalline (nc-Ti) were examined. Bulk nc-Ti was fabricated by hydrostatic extrusion (HE) which is one of the severe plastic deformation methods (SPD). The elastic modulus of mc-Ti and nc-Ti were compared with the aim to analyze the influence of the nanostructure of titanium on its elastic modulus. The mc-Ti and nc-Ti samples were subjected to uniaxial tensile tests at various strain rates and various values of stress. Generally, higher elastic modulus values were obtained in microcrystalline titanium. The elastic modulus of mc-Ti was evaluated at 107 GPa on average, whereas the elastic modulus of nc-Ti was 94 GPa on average. The nanocrystalline titanium had a lower elastic modulus than its microcrystalline counterpart by 13% on average, which can be attributed to the presence of significant volume of amorphous regions in the structure. Moreover, in this case a lower standard deviation of all the results was obtained. In most cases, with higher applied stress (load) the value of the modulus was lower, whereas at higher strain rates its value was higher.

3

Mechanical properties of titanium processed by hydrostatic extrusion

Topolski K., Garbacz H., Wieciński P., Pachla W., Kurzydłowski K. J.

Archives of Metallurgy and Materials

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2012

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Vol. 57, iss. 3

863-867

EN

The mechanical properties of titanium Grade 2 subjected to the hydrostatic extrusion technique (HE) were investigated. The hydrostatic extrusion technique is a method which refines the titanium grains to a nano-metric size. Compared with coarse grained titanium (CG-Ti), nanocrystalline titanium (NC-Ti) is characterized by a much higher yield stress, tensile strength and microhardness. The yield stress of NC-Ti determined in tensile tests is higher than that measured in compression test. The Young modulus of NC-Ti is slightly lower than that of CG-Ti.

PL

Przedmiot badań stanowiły właściwości mechaniczne tytanu Grade 2 poddanego wyciskaniu hydrostatycznemu. Technika wyciskania hydrostatycznego jest metodą, która umożliwia rozdrobnienie ziarna tytanu do wielkości nano-metrycznej. W porównaniu z tytanem gruboziarnistym (CG-Ti), tytan nanokrystaliczny (NC-Ti) charakteryzuje się o wiele wyższą granicą plastyczności, wytrzymałości na rozciąganie oraz mikrotwardością. Granica plastyczności NC-Ti wyznaczona podczas testów rozciągania jest wyższa niż granica plastyczności wyznaczona w testach ściskania. Natomiast moduł Young'a nanokrystalicznego tytanu jest nieznacznie mniejszy niż moduł tytanu gruboziarnistego.

4

Surface modification of titanium subjected to hydrostatic extrusion

Topolski K., Garbacz H., Kurzydłowski K. J.

Inżynieria Materiałowa

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2010

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Vol. 31, nr 3

336-339

EN

The study is concerned with grain refinement in titanium by hydrostatic extrusion (HE) which belongs to the techniques of severe plastic deformation (SPD). Prior to extrusion titanium samples were coated with aluminum. Extrusion process was carried out with varied number of passes and the degree of diameter reduction. The surface modification was aimed at simplifying and optimizing the hydroextrusion process. It has been found that the aluminum coatings allowed to reduce the maximum extrusion pressure, decrease the number of extrusion passes and minimize the die wear.

PL

Praca dotyczy rozdrabniania ziarna w tytanie metodą wyciskania hydrostatycznego (HE), które jest zaliczane do metod dużego odkształcenia plastycznego (SPD). W przeprowadzonych badaniach tytanowe wsady przed wyciskaniem pokryte zostały powłokami aluminium. Wyciskanie hydrostatyczne prowadzono, stosując rożne parametry procesu, w tym rożną liczbę etapów i stopień redukcji przekroju. Modyfikacja powierzchni wsadu miała na celu zoptymalizowanie oraz uproszczenie hydroekstruzji tytanu. Uzyskane wyniki dowiodły licznych korzyści wynikających z zastosowania powłok aluminium w procesie wyciskania hydrostatycznego tytanu. Należą do nich przede wszystkim obniżenie maksymalnego ciśnienia, zmniejszenie liczby operacji wyciskania oraz mniejsze zużycie matrycy.

5

Statistical Description of Magnetic Domains in the Two Dimensional Ising Model

Lukierska-Walasek K., Topolski K.

Computational Methods in Science and Technology

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2010

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Vol. 16, No. 2

173-176

EN

The Zipf-Mandelbrot power law and its connection with the inhomogeneity of the system has been used. We describe the statistical distributions of the domain masses in the Ising model near the phase transition induced by the temperature. For the large domain masses we observe the characteristic irregularities. The statistical distribution near the critical point appears to be of the Pareto type.

6

Limit theorems for stochastic dynamical system arising in ising model analysis

Szwarc R., Topolski K.

Probability and Mathematical Statistics

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2008

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Vol. 28, Fasc. 2

257--270

EN

A simple stochastic dynamical system defined on the space of doubly-infinite sequences of real numbers is considered. Limit theorems for this system are proved. The results are applied to the physical model of wetting of the flat heterogeneous wall.

7

Wyciskanie hydrostatyczne jako technika wytwarzania nanotytanu

Topolski K., Garbacz H., Pachla W., Kurzydłowski K.J.

Prace Naukowe Politechniki Warszawskiej. Mechanika

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2007

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z. 216

113--118

PL

Wyciskanie hydrostatyczne należy do procesów kształtowania objętościowego materiałów. Jest to technika spełniająca kryteria wyciskania współbieżnego, jednakże wyraźnie odbiegająca od klasycznych procesów tego typu. Wyciskanie hydrostatyczne umożliwia wytwarzanie szerokiej gamy produktów o różnorodnych kształtach przekroju poprzecznego. Proces wyciskania hydrostatycznego stanowi jedną z technik tzw. dużego odkształcenia plastycznego – Severe Plastic Deformation (SPD). Technologia hydroekstruzji pozwala również na świadome i kontrolowane kształtowanie mikrostruktury oraz właściwości materiału. Umożliwia rozdrobnienie ziarna do poziomu nanomertycznego, co skutkuje wyraźnym podwyższeniem właściwości mechanicznych materiału. W pracy przybliżono technikę hydroekstruzji oraz zaprezentowano uzyskane wyniki na przykładzie tytanu.

EN

Hydrostatic extrusion (HE) is classify to the volumetric formation processes of materials. It is a technique fulfiling the criterions of direct extrusion, however differ from classic processes this type. Hydroextrusion makes possible to manufacture products with varied shapes of cross section. This process is a one of Severe Plastic Deformation (SPD) technique. Hydroextrusion technology allows on consciously and controlled structure formation and material properties also. This technology makes possible to grain refinement and decrease its size to the nanometric scale. In consequence of this phenomenon increase of the mechanical properties is observed. In this paper a hydroextrusion technology was discussed and the results obtained for titanium were presented.

8

On the unbounded solutions for parabolic differential-functional Cauchy problem

Topolski K.

Demonstratio Mathematica

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2007

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Vol. 40, nr 1

151-160

EN

We consider the initial value problem for second order differential–func- tional equation. Functional dependence on an unknown function is of the Hale type. We prove the existence theorem for unbounded classical solution. Our formulation admits a large group of nonlocal problems. We put particular stress on “retarded and deviated” argument as it seems to be the most difficult.

9

Hydrostatic extrusion of titanium - process parameters

Topolski K., Garbacz H., Pachla W., Kurzydłowski K.J.

Advances in Materials Science

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2007

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Vol. 7, nr 4(14)

114-120

EN

Hydrostatic extrusion (HE), which belongs to the severe plastic deformation (SPD) techniques, permits producing titanium with a nano-crystalline structure. The homogeneity of the microstructure, the volume of the product and also the quality of its surface depend on the parameters of the hydrostatic extrusion process. The study was concerned with the effects of the deformation magnitude and the number of the HE cycles upon the microstructure and mechanical properties of the titanium being treated. The course of the HE process and its final product appeared to depend greatly on the process temperature and the starting state of the titanium surface. The results obtained during the experiments permitted optimizing the HE process, and improving the performance and mechanical properties of the final product.