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1

Microstructural Aspects of Bifocal Laser Welding of TRIP Steels

Grajcar A., Grzegorczyk B., Różański M., Stano S., Morawiec M.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2A

611--618

EN

This work is concerned with comparative tests involving single-spot and twin-spot laser welding of thermomechanically rolled TRIP steel. The welding tests were carried out using keyhole welding and a solid state laser. In the case of twin-spot laser beam welding, the power distribution of beams was 50%:50%. The changes in macro- and microstructures were investigated using light and scanning electron microscopy. Three main zones subjected to the tests included the fusion zone, the heat affected zone and the intercritical heat affected zone (transition zone between the base material and the HAZ). Special attention was paid to the effect of various thermal cycles on the microstructure of each zone and on martensite morphology. The tests involved hardness measurements carried out in order to investigate the effect of different microstructures on mechanical properties of welds.

2

Influence of plastic deformation temperature on the structure and mechanical properties of low-alloy copper alloys with Co, Ni and B

Grzegorczyk B., Ozgowicz W.

Archives of Materials Science and Engineering

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2017

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Vol. 84, nr 2

49--57

EN

Purpose: This work presents the influence of chemical composition and plastic deformation temperature of CuCoNi and CuCoNiB as well as CuCo2 and CuCo2B alloys on the structure, mechanical properties and, especially on the inter-crystalline brittleness phenomenon and ductility minimum temperature effect in tensile testing with strain rate of 1.2·10-3 s-1 in the range from 20°C to 800°C. Design/methodology/approach: The tensile test of the investigated copper alloys was realized in the temperature range of 20-800°C with a strain rate of 1.2·10-3 s–1 on the universal testing machine. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope. Findings: Low-alloy copper alloys such as CuCo2 and CuCo2B as well as CuCoNi and CuCoNiB show a phenomenon of minimum plasticity at tensile testing in plastic deforming temperature respectively from 500°C to 700°C for CuCo2, from 450°C to 600°C for CuCo2B and from 450°C to 600°C for CuCo2B and from 500°C to 600°C for CuCoNiB. Practical implications: In result of tensile tests of copper alloys it has been found that the ductility minimum temperature of the alloys equals to about 500°C. At the temperature of stretching of about 450°C the investigated copper alloys show maximum strength values. Originality/value: Based on the test results the temperature range for decreased plasticity of CuCoNi and CuCoNiB as well as CuCo2 and CuCo2B alloys was specified. This brittleness is a result of decreasing plasticity in a determined range of temperatures of deforming called the ductility minimum temperature.

3

Corrosion Resistance and Pitting Behaviour of Low-Carbon High-Mn Steels in Chloride Solution

Grajcar A., Grzegorczyk B., Kozłowska A.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

825--832

EN

Corrosion resistance of the X4MnSiAlNbTi27-4-2 and X6MnSiAlNbTi26-3-3 type austenitic steels, after hot deformation as well as after cold rolling, were evaluated in 3.5% NaCl solution using potentiodynamic polarization tests. A type of nonmetallic inclusions and their pitting corrosion behaviour were investigated. Additionally, the effect of cold deformation on the corrosion resistance of high-Mn steels was studied. The SEM micrographs revealed that corrosion damage formed in both investigated steels is characterized by various shapes and an irregular distribution at the metallic matrix, independently on the steel state (thermomechanically treated or cold worked). Corrosion pits are generated both in grain interiors, grain boundaries and along the deformation bands. Moreover, corrosion damage is stronger in cold deformed steels in comparison to the thermomechanically treated specimens. EDS analysis revealed that corrosion pits preferentially nucleated on MnS and AlN inclusions or complex oxysulphides. The morphology of corrosion damage in 3.5% NaCl supports the data registered in potentiodynamic tests.

4

The Portevin –Le Chatelier Effect and Acoustic Emission of Plastic Deformation CuZn30 Monocrystals

Ozgowicz W., Grzegorczyk B., Pawełek A., Piątkowski A., Ranachowski Z.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 1

183--188

EN

The paper presents the investigation of the relation between the acoustic emission (AE) and instability of plastic deformation type Portevin-Le Chatelier (PLC) of single-phase brass CuZn30 monocrystals with crystallographical orientation [13 9]. The monocrystals have been investigated applying the method of free compression at a constant strain rate and the temperature within the range from 200°C to 400°C, simultaneously recording PLC phenomenon by means of acoustic emission. During hot axial compression tests the correlation between work-hardening curves σ - ε, which display PLC effect and characteristic of acoustic emission signals has been found. Moreover, it was proved that in the range of the PLC effect, the acoustic signal is an impulse a character of cyclic repeatability, distinctly correlated qualitatively with the stress oscillations on the curves σ - ε. The analysis of the obtained results leads to the conclusion that in the tested monocrystals the effect PLC is probably controlled by complex processes similar to the phenomenon of dynamic strain ageing (DSA), which are described by diffusion models.

PL

Streszczenie W pracy badano zależność między emisją akustyczną (EA), a niestabilnością odkształcenia plastycznego typu Portevin Le Chatelier monokryształów jednofazowego mosiądzu CuZn30 o orientacji krystalograficznej [13 9]. Monokryształy poddano próbie swobodnego ściskania przy stałej prędkości odkształcenia w zakresie temperatury od 200°C do 400°C stosując jednocześnie pomiar emisji akustycznej. Określono zależność pomiędzy przebiegiem krzywych umocnienia σ - ε wykazujących efekt PLC. a charakterystyką sygnałów emisji akustycznej generowanych w badanej próbie ściskania jednoosiowego. Stwierdzono, że w zakresie występowania efektu PLC podczas próby ściskania, sygnał EA ma charakter impulsu cyklicznego, wyraźnie skorelowany jakościowo z oscylacjami naprężeń na krzywych σ - ε. Analiza uzyskanych wyników pozwala przypuszczać, że w badanych monokryształach efekt PLC jest kontrolowany prawdopodobnie przez złożone procesy podobne do zjawisk starzenia dynamicznego po zgniocie (DSA), które są opisane modelami dyfuzyjnymi.

5

Study on Non-Metallic Inclusions in Laser-Welded TRIP-Aided Nb-Microalloyed Steel

Grajcar A., Różański M., Kamińska M., Grzegorczyk B.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 3

1163--1169

EN

The work concerns the studies on non-metallic inclusions occuring in laser-welded Si-Al TRIP steel containing Nb and Ti microadditions. Laser welding tests of 2 mm thick thermomechanically rolled sheets were carried out using keyhole welding and a solid-state laser. The results of laser welding in the air atmosphere for the heat input value of 0.048 kJ/mm are included. The distribution, type and chemical composition of non-metallic inclusions formed in the base metal, heat-affected zone, and fusion zone are analysed in detail. It was found that the base metal contains rare, fine oxysulphides. Their chemical composition was modified by rare earth elements. Numerous oxide inclusions of a various size and a chemical composition occur in the fusion zone. The dependence between a size of particles and their chemical composition was observed. A microstructure of steel was assessed using light microscopy and scanning electron microscopy techniques.

PL

Praca dotyczy badań wtrąceń niemetalicznych występujących w przetapianej laserowo stali TRIP typu Si-Al zawierającej mikrododatki Nb i Ti. Próby spawania laserowego odwalcowanych termomechanicznie taśm o grubości 2 mm przeprowadzono z wykorzystaniem lasera na ciele stałym i techniki głębokiego przetopienia. Przedstawiono wyniki przetapiania laserowego próbek z energią liniową 0.048 kJ/mm w atmosferze powietrza. Szczegółowej analizie poddano rozkład, rodzaj i skład chemiczny wtrąceń niemetalicznych tworzących się w materiale rodzimym, strefie wpływu ciepła i strefie przetopionej. Stwierdzono, że w materiale rodzimym występują nieliczne, drobne wtrącenia siarczkowo-tlenkowe, których skład chemiczny został zmodyfikowany przez pierwiastki ziem rzadkich. W strefie przetopionej występują liczne wtrącenia tlenkowe o zróżnicowanej wielkości i składzie chemicznym. Zaobserwowano zależność między wielkością wtrąceń a ich składem chemicznym. Mikrostrukturę stali określono z wykorzystaniem mikroskopii świetlnej i skaningowej mikroskopii elektronowej.

6

Investigation of the Portevin-Le Chatelier effect by the acoustic emission

Grzegorczyk B., Ozgowicz W., Kalinowska-Ozgowicz E., Kowalski A.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 60, nr 1

7--14

EN

Purpose: The aim of this paper is to determine the relation existing between the behaviour of the signals of acoustic emissions generated in the course of plastic deformation at elevated temperature, and the shape of the work-hardening curves σ-ε and the Portevin - Le Chatelier effect. Design/methodology/approach: Single crystal was investigated applying the method of free compression at a constant strain rate and a temperature within the range from 20°C to 400°C at a strain rate of 10-5 sec-1to 10-1 sec-1, simultaneously recording this phenomenon by means of acoustic emission. Findings: The analysis of the results of these investigations permitted to prove considerable relations between the work-hardening curve σ-ε displaying the PLC effect and the characteristics of the signals of the acoustic emission generated in the uniaxial compression. Practical implications: The AE method applied in the process of plastic deformation of single crystals of the alloy CuZn30 displays also a dependence of the activity of acoustic emissions on the stage of strain-hardening of the investigated alloy. Originality/value: In the range of the occurrence of the PLC effect during the compression test of the investigated single crystals the signal AE displays a cyclic character, distinctly correlated qualitatively with the oscillations of stresses on the curve σ-ε.

7

Segregation of alloying elements in thermomechanically rolled medium-Mn multiphase steels

Grajcar A., Kamińska M., Opiela M., Skrzypczyk P., Grzegorczyk B., Kalinowska-Ozgowicz E.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 2

256--264

EN

Purpose: The aim of the paper is to assess the tendency of alloying elements to macro- and microsegregation during hot-forging and successive thermomechanical rolling of medium-Mn Al-bearing steel sheets. Design/methodology/approach: The macro- and microsegregation of alloying elements was assessed by EDS and WDS measurements across the thickness of the roughly-forged flats and thermomechanically processed 3.3 mm sheets. The microstructure was revealed using combined methods of optical microscopy (OM) and scanning electron microscopy (SEM). Morphological features of microstructural constituents were discussed with focusing on retained austenite. Findings: It was found that the final multiphase microstructure is mainly dependent on the Mn content and the effect of Nb microaddition is relatively low. The 3Mn steels possess very fine bainite-based microstructures whereas the steels containing 5% Mn are characterized by lath bainitic-martensitic microstructures. All the steels contain retained austenite as fine granules or layers located between bainitic ferrite laths. Some fraction of martensite-austenite (M-A) islands was also identified. The tendency of Mn and Al to macrosegregation was found after the initial hot-forging. It disappears after successive rough and thermomechanical rolling whereas thin martensite and martensite-austenite microbands as a result of Mn microsegregation locally occur. Research limitations/implications: Further investigations are required to quantify the local changes of chemical composition especially in formed microbands and X-ray quantitative phase analysis should be applied to assess a fraction of retained austenite. Practical implications: The knowledge of the macro- and microsegregation of alloying elements in advanced medium-Mn steels containing retained austenite can be useful in designing the thermomechanical rolling procedures of multiphase steel sheets. Originality/value: A problem of macro- and microsegregation of Mn and Al in advanced high strength steels, which belong to the third generation of automotive steels was discussed with concentrating on Mn and Nb microaddition effects.

8

Metallographic aspects of deformed monocrystals of CuZn30 alloys

Grzegorczyk B., Ozgowicz W., Kalinowska-Ozgowicz E., Kowalski A., Pałka P.

Archives of Materials Science and Engineering

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2012

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Vol. 54, nr 1

29-36

EN

Purpose: The aim of the paper is to present the technique of production and the analysis of the structures of CuZn30 monocrystals compressed at a temperature of 20°C up to 400°C at a strain rate of 10-5 sec-1 to 10-1 sec-1. Design/methodology/approach: The range of investigations comprised the production of monocrystals for tests, the determination of their crystallographic orientation, the deformation of selected monocrystals by compressing them within the temperature range from 20°C to 400°C at a strain rate of 10-5 sec-1 to 10-1 sec-1, as well as observations of the structures on an optical microscope. Findings: The analysis of the results of these investigations permitted to prove a considerable influence of the temperature, the strain rate and the crystallographic orientation on the metallographic effects of the work hardening of the CuZn30 alloy with the orientation [1 3 9 ]. Practical implications: In the microstructures of the investigated monocrystals typical effects of plastic deformation were observed in the form of parallel cruciform lines and slip zones with locally intensified densities in various ranges of the cross-section of the sample and bands of deflection with weakly visible slip lines in the original system. Originality/value: The analysed microstructures of compressed monocrystals prove that the main mechanism of plastic deformation is the slide. Of essential influence on the structure of plastically deformed monocrystals with the orientation [1 3 9 ] are both the temperature and the strain rate.

9

The operations of building companies in Wrocław in the 2nd half of the 19th century

Grzegorczyk B.

Architectus

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2012

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Nr 1(31)

35--41

EN

One of the problems of Wrocław around 1850 – which in fact is rarely noticed by researchers – due to the fact that other issues are most often studied – is the issue of planned housing development and building societies closely connected with it which were established in those times. In 1840 there was an economic revival along with a population growth and decisions taken by the members of the city government at that time resulted in the construction boom. There was an increased demand for building plots whose values were still growing. It could be observed that there appeared a necessity to build not only tenement houses for rich Wroclaw inhabitants, but there was also a need to erect cheaper houses for poorer inhabitants of the town. It is very characteristic that patterns were derived from English experiences and ‘The Society for Improving the Conditions of the Labouring Classes’ that was established in London in 1844 was presented as an example of a newly understood construction organisation. However, the English Society, similarly to the Amsterdam society called ‘Vereeniging ten Behoven der Arbeiderklasse’, conducted half-charity business, whereas in the territory of Wroclaw the business was carried out in two ways, namely, two groups of societies with different goals appeared. Societies with a definitely commercial character belonged to the first group and they were aimed at gaining building territories, dividing them into building plots and then selling them (for example, Wroclaw Construction Society – 1858, Wroclaw Construction Bank – 1871). It is worth emphasising that some societies did not only deal with selling new plots of land but they also employed architects who designed buildings, constructed them and then sold to private persons or institutions (e.g. Maciejowe Field – Construction Limited Partnership Society – 1869, Silesian Society of Real Estate Trade – 1872). The other group consisted of societies which conducted business on the basis of a cooperative, however, differently than in England or Netherlands, i.e. they were established on the initiative of persons who were united by a necessity to get a relatively cheap flat (e.g. Wroclaw Savings and Construction Cooperative – 1868). The activity of the abovementioned companies, which was outlined in the article, clearly demonstrates not only constant competition but also a great contribution of the discussed institutions in the process of co-creating the planned city development.

PL

Jednym z problemów Wrocławia około roku 1850 – nota bene problemu, który tylko okazjonalnie, z racji omawiania najczęściej innych kwestii, zwraca uwagę badaczy – jest sprawa ówczesnej planowanej gospodarki mieszkaniowej i ściśle z nią powiązanych, tworzonych wówczas towarzystw budowlanych. Nie ulega wątpliwości, że był to wyraz aktywizacji gospodarczej Niemiec po roku 1840. Wraz z ożywieniem gospodarczym nastąpił w mieście przyrost ludności, a podejmowane wówczas przez członków zarządu miasta decyzje zaowocowały koniunkturą budowlaną. Uwidocznił się zwiększony popyt na działki budowlane, których wartość stale rosła. Można zauważyć, że w mieście pojawiła się konieczność wznoszenia nie tylko kamienic czynszowych dla zamożnych wrocławian, ale także budowy tańszych domów dla uboższych mieszkańców. Znamienne jest, że wzorce czerpano przede wszystkim z doświadczeń angielskich, a jako przykład nowo pojętej organizacji budowlanej podawano „Society for Improving the Conditions of the Labouring Classes”, założone w Londynie w 1844 r. O ile jednak angielska spółka, podobnie jak amsterdamskie stowarzyszenie „Vereeniging ten Behoven der Arbeiderklasse”, prowadziła działalność na poły charytatywną, o tyle na terenie Wrocławia prowadzono ją na dwa sposoby – pojawiły się dwie grupy stowarzyszeń o odmiennych celach. Do pierwszej z nich należy zaliczyć towarzystwa o zdecydowanie komercyjnym charakterze, które dążyły do pozyskania terenów budowlanych, następnie podziału ich na działki i sprzedaży (np. „Wrocławskie Towarzystwo Budowlane” – 1858, „Wrocławski Bank Budowlany” – 1871). Warto przy tym zaznaczyć, że część towarzystw nie zajmowała się li tylko sprzedażą nowo wytyczonych działek, zatrudniano bowiem architektów, którzy projektowali budynki, następnie realizowane i odsprzedawane prywatnym osobom bądź instytucjom (np. „Pole Maciejowe – Towarzystwo Budowlane – Komandytowe” – 1869, „Śląskie Towarzystwo Handlu Nieruchomościami” – 1872). Drugą grupę natomiast tworzyły towarzystwa, które działały na zasadach spółdzielni, jednak inaczej niż w Anglii czy Niderlandach, powstawały one przede wszystkim z inicjatywy osób, które jednoczyła konieczność zdobycia stosunkowo taniego mieszkania (np. „Wrocławska Spółdzielnia Oszczędnościowo-Budowlana” – 1868). Naszkicowana w artykule działalność powyższych spółek jednoznacznie dowodzi nie tylko stałej rywalizacji, ale również ogromnego wkładu, jaki wniosły omawiane instytucje we współtworzenie planowego rozwoju miasta.

10

Thermomechanical treatment of low-alloy copper alloys of the kind CuCo2Be and CuCo1NiBe

Ozgowicz W., Kalinowska-Ozgowicz E., Grzegorczyk B.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 46, nr 2

161--168

EN

Purpose: The aim of the investigations is to test the influence of the complex thermomechanical treatment on the structure and mechanical properties of low-alloy copper alloys with cobalt, beryllium and nickel of the kind CuCo2Be (CB4) and CuCo1NiBe (CCNB). Design/methodology/approach: The range of investigations comprises an analysis of the complex technique of thermomechanical treatment of the investigated alloys and the conventional thermal treatment of these alloys, the analysis of their chemical composition, a static tensile test, measurement of their hardness, observations of their structure on a light microscope and a fractographic analysis on an electron scanning microscope. Findings: The analysis of the results of investigations concerning the mechanical effect properties permitted to determine the effect of the combined thermomechanical treatment and the comparatively performed precipitation hardening on the structure and mechanical properties of the investigated low-alloy kinds of copper. The character of cracking in the course of stretching were determined basing on fractographic tests. Practical implications: The investigated copper alloys subjected to a complex thermomechanical treatment display a higher strength and lower plastic properties in comparison with these properties achieved by means of the conventional heat treatment. Originality/value: Complex thermomechanical treatment ensures an optimal strength of the investigated alloys as well as satisfying plastic properties.

11

Effects of Mn and Nb on the macro- and microsegregation in high-Mn high-Al TRIP steels

Grajcar A., Kalinowska-Ozgowicz E., Opiela M., Grzegorczyk B., Gołombek K.

Archives of Materials Science and Engineering

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2011

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Vol. 49, nr 1

5-14

EN

Purpose: The aim of the paper is to determine the effects of Mn and Nb on the macro- and microsegregation of new-developed (3-5)Mn 1.5Al TRIP steels in the as-cast state and after hot forging. Design/methodology/approach: To assess possible macro- and microsegregation the chemical composition was investigated in the macro scale by OES and by the use of EDS in microregions. To reveal the macrostructure the ingots were etched by Oberhoffer’s reagent. The chemical composition along a diameter of the ingots was tested as well as in different regions of the plastically deformed flats. Metallographic investigations were carried out using optical (OM) and scanning electron microscopy (SEM). Findings: The Mn and Nb contents have significant effects on the obtained bainitic-martensitic structures and the morphology of retained austenite. The tendency to macrosegregation of Mn and Al between middle and external parts of the as-cast ingots and hot forged flats was detected. The Nb micoalloying results in the overall refinement of obtained microstructures and reduces the identified segregation of Al and Mn. A little microsegregation of these alloying elements between structural constituents was also detected. Research limitations/implications: Further investigations to describe in detail the identified structural constituents and the tendency of alloying elements to segregation in the thermomechanically rolled sheets are in progress. Practical implications: The knowledge of the macro- and microsegregation of Mn and Al in the TRIP steels with a high fraction of retained austenite is of primary importance for the manufacturing paths of these multiphase structure steels. Originality/value: A problem of segregation of Al and Mn in advanced high strength steels with and without Nb microaddition was described and interesting types of bainitic structures were identified.

12

The microstructure and mechanical properties of the alloy CuZn30 after recrystallizion annealing

Ozgowicz W., Kalinowska-Ozgowicz E., Grzegorczyk B.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 40, nr 1

15-24

EN

Purpose: The aim of the investigations is to determine the influence of the recrystallization temperature on the microstructure and mechanical properties of the brass CuZn30 subjected to cold deformation in the process of rolling at various degrees of strain. Design/methodology/approach: The brass CuZn30 was recrystallization annealed within the temperature range of 300-650°C after cold rolling with the strain of 15.8-70.2%. The tensile test was carried out by the use of universal testing machine. Metallographic observations were performed on an optical microscope and fractographic tests on a scanning electron microscope. The hardness was also measured. Findings: The analysis of the results of investigations concerning the mechanical properties permitted to determine the effect of the temperature of recrystallization annealing on the strength and plastic properties of the investigated brass, subjected to cold deformation with a varying strain in the course of rolling. The character of fracture after decohesion in the tension test was determined basing on fractographic investigations. Practical implications: An increase of the recrystallization temperature within the range of 400-650°C results in a deterioration of the mechanical properties of the brass CuZn30 and an increase of its plastic properties. Originality/value: The results of the investigation revealed the occurrence of the phenomenon of heterogeneous plastic deformation in the recrystallized alloy.

13

The building of the Gotthelf Foundation in the context of the architectural tradition

Grzegorczyk B.

Architectus

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2010

|

Nr 1(27)

39--46

EN

In the year 1914, when the construction work for the new building of the Józef Gotthelf Foundation came to an end, its location, far from the hustle and bustle of the city, in the midst of meadows and fields, where only from time to time the sough of trees from the nearby cemetery could be heard - had to be associated with an immense desolation (Fig. 1). After all the only road in this part of the city was the Hallera street (Kürassierstr.), which was laid out during the sixties of the 19th century for the needs of the nearby barracks. Nevertheless this lonely building with six mansards raising above the roof slopes was visible from far. Although it was modest, it was not deprived of sophistication - and so it stays until today, distinctly appearing at the background of the adjacent blocks of flats of the estate built here in 1920.

PL

Wzniesiony w roku 1914 budynek fundacji Józefa Gotthelfa, z sześcioma szczytami mansard wznoszącymi się nad połaciami dachu, widoczny z daleka, choć skromny, nie był pozbawiony elegancji - i taki pozostał do dziś, wyraziście rysując się na tle sąsiadujących z nim bloków mieszkalnych osiedla założonego tutaj w latach dwudziestych XX w. Znamienne jest, że powstawanie tej budowli było bacznie obserwowane, zwłaszcza przez środowisko żydowskie, z którym związana była osoba fundatora. Gdy jednak budynek oddano do użytku, dalszym jego dziejom nie poświęcano uwagi. Tradycyjnie traktowano to założenie jako awangardowe - w tym czasie - rozwiązanie budowli o charakterze socjalnym i w związku z tym autorstwo przypisywano Maksowi Bergowi. Niniejszy artykuł, na podstawie przeprowadzonych badań dotyczących historii powstania budynku, wspartych kwerendą archiwalną oraz analizą genezy formy architektonicznej, polemizuje z przyjętą hipotezą. Wybrane przykłady budowli socjalnych zarówno o charakterze paternalistycznym (zrealizowane przez firmę Kruppa w Essen 1863), jak i budowanych z pobudek filantropijnych (np. Planciusstraat przez amsterdamską spółdzielców Vereeniging ten behoeve der Arbeidersklasse, 1852) czy też zainspirowanych ideami utopijnymi (np. założony przez Jeana Baptista Godina Familister de Guise, 1859-1870) wznoszonych w Europie w stuleciu XIX wskazują, że budynek fundacji Gotthelfa trudno jednak uznać za awangardowe rozwiązanie w owym czasie. Wydaje się również, o czym świadczą przytoczone fakty, że autorstwo należy przypisać ówczesnemu współpracownikowi Berga - Karlowi Klimmowi.

14

The influence of the temperature of plastic deformation on the structure and mechanical properties of copper alloys CuCo2Be and CuCo1Ni1Be

Ozgowicz W., Grzegorczyk B.

Archives of Materials Science and Engineering

|

2009

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Vol. 39, nr 1

5-12

EN

Purpose: The aim of the paper is to determine the influence of temperature of plastic deformation on the structure and mechanical properties of copper alloy of the CuCo2Be and CuCo1Ni1Be during a tensile test applied on electrodes to welders. Design/methodology/approach: The tensile test of the investigated copper alloys was realized in the temperature range of 20-800°C with a strain rate of 1.2⋅10-3s-1 on the universal testing machine. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope. Findings: The mechanical properties of alloys as well as the range of occurrence of the Portevin - Le Chatelier (PLC) phenomenon was determined on the basis of F-ΔL curves formed by tensile tests; however the character of fracture during the break of the samples was defined on the basis of fractographic investigations. Research limitations/implications: Practical implications: In result of tensile tests of copper alloys it has been found that the PLC effect occurs in both alloys in the temperature range of 150-350°C. However, the ductility minimum temperature of the alloys equals about 500°C. At the temperature of stretching of about 450°C the investigated copper alloys show maximum strength values. Originality/value: The type of "teething" on the load - displacement curves was defined, according to the classification received in literature. The dependence εkr = f(t) was marked too.

15

The influence of the temperature of tensile test on the structure and plastic properties of copper alloy type CuCr1Zr

Ozgowicz W., Kalinowska-Ozgowicz E., Grzegorczyk B.

Journal of Achievements in Materials and Manufacturing Engineering

|

2008

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Vol. 29, nr 2

143-146

EN

Purpose: The purpose of this paper is to determine the influence of temperature of plastic deformation on the structure and mechanical properties of copper alloy of the type CuCr1Zr during a tensile test. Design/methodology/approach: The tensile test of the investigated alloy was realized in the temperature range of 20 ÷ 700° C with strain rate of 1.2 • 10 -3 s -1. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope. Findings: The mechanical properties of alloy as well as the range of occurrence of the Portevin - Le Chatelier phenomenon was determined on the basis of σ - ε curves formed by tensile tests; however the character of fracture during the break of the samples was defined on the basis of fractographic investigations. Practical implications: In result of tensile tests of copper alloy it has been found that the PLC effect occurs in temperature range of 250÷400 ° C. However, the ductility minimum temperature of the alloy equals about 550° C. Originality/value: A correlation of temperature of PLC effect was achieved with a qualitative description of the type of "teething" on the σ - ε curves, compatible with the classification quoted in literature.

16

Analysis of the Portevin - Le Chatelier effect in tin bronzes at elevated temperatures

Ozgowicz W., Grzegorczyk B.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 2

281-289

EN

Purpose: The aim of the present paper is the determination of the effect of the chemical composition and temperature of deformation of standardized tin bronzes and bronze modified with zirconium on the Portevin-Le Chatelier (PLC) phenomenon, mainly basing on the shape of stress-strain curves within the temperature range of 100-300° C and observations of their structure. The reasons of the occurrence of such en effect are so far no fully known and explained and the opinions concerning is physical basis vary. Design/methodology/approach: Of essential design in this research is determination of the dependence of PLC effect on the chemical composition, temperature and strain rate and the preliminary heat treatment and grain size. The main method used in this investigation is tensile test at elevated temperature. Findings: The main conclusions are following: the PLC effect on tin bronzes with a micro-addition of zirconium in an amount of 0.01-0.05% depends the temperature of deformation in the tensile test in the range of 100-300° C and the chemical composition of the alloys; the type of serration revealed on the σ-ε curve depend mainly on the temperature of deformation and can be differ during the respective stages of the analyzed curves. Practical implications: In this paper implications for practice are not taken into consideration. Originality/value: In this paper an additive type of serration observed on the curves σ -ε , denoted by the symbol D, is new.