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1

Effect of Welding Technique and Thermal Heatment Parameters on Abrasive Wear of Steel S355

Konat Łukasz, Białobrzeska Beata

Tribologia

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2022

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nr 3

25--38

EN

The paper presents technological and microstructural aspects of welding and post-weld heat treatment of the S355 constructional steel welded joints. It was found that welding this steel resulted in a wide heataffected zone with diverse microstructures conducive to lower abrasive-wear resistance and worse mechanical characteristics of the steel. In this connection, the welding technique of the S355 steel was suggested, as well as conditions and parameters of the post-weld heat treatment, which made it possible to obtain – in the entire welded joint area – the microstructures characterised by high mechanical properties and increased resistance to abrasive wear. It was shown that the suggested set of technological operations applied to the S355 steel resulted, under laboratory conditions, in a significant increase of relative abrasive-wear resistance, determined by the abrasion test with use of the of loose aloxite 90.

PL

W pracy przedstawiono technologiczne i mikrostrukturalne aspekty wykonywania i obróbki cieplnej połączeń spawanych stali konstrukcyjnej S355. W wyniku przeprowadzonych badań stwierdzono, że zastosowanie do łączenia tej stali procesów spawalniczych prowadzi do powstawania szerokiej strefy wpływu ciepła, charakteryzującej się zróżnicowanymi zmianami mikrostrukturalnymi, sprzyjającymi obniżeniu odporności na zużywanie ścierne oraz pogorszeniu charakterystyki wytrzymałościowej rozpatrywanej stali. W związku z tym, zaproponowano optymalną technologię spawania stali S355 oraz warunki i parametry postobróbki cieplnej, prowadzących do uzyskania w całym obszarze połączenia spawanego mikrostruktur odznaczających się wysokimi parametrami mechanicznymi oraz podwyższoną odpornością na procesy zużycia ściernego. Wykazano, iż przedstawiony w stosunku do stali S355 zakres operacji technologicznych w warunkach laboratoryjnych skutkował znacznym podwyższeniem względnej odporności na zużywanie ścierne, wyznaczonej w warunkach ścierania w obecności luźnego ścierniwa – elektrokorund 90.

2

Investigations of the structure and hardness of dissimilar steel-to-aluminum joints made using laser welding technology

Misiura Karolina, Konieczny Jarosław, Labisz Krzysztof, Boris Renata

Transport Problems

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2022

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T. 17, z. 1

73--86

EN

Since welding technology is currently used to assemble the frame of driver’s seats, it is important to develop laser welding technology for steel and aluminium. For this reason, the purpose of the present work was to examine the structure and selected properties of aluminium-steel joints using the example of an EN AW-6060 aluminium alloy and DC04 low-alloy steel welded in laser technology. Overlapping joints were made, weld type -following the hole laser welding method -laser beam (LB) using a high power disk laser (TRUMPF TruDisk3302), in which the active medium is a yttrium-aluminium crystal (YAG). Metallographic microstructure investigations were carried out using a light microscope from Carl Zeiss - Observer Z1m, and the weld microstructures were investigated using an SEM Supra 35 microscope, also from Carl Zeiss. The chemical composition analysis in micro-areas was carried out using an X-ray energy dispersion spectrometer from EDAX, which was a part of the SEM Supra 35. The hardness of the substrate material and the welded area was measured following the Vickers method using an FM-ARS 9000 micro hardness tester from Tokyo, Japan. It was found that there is a potential for commercial use of laser welding to make a low-carbon steel-aluminium alloy joint. During the formation of the weld in its microstructure, intermetallic compounds of the FexAly type were created, which significantly reduced the mechanical and plastic properties of the joint. The hardness of the weld created wasabout seven times higher than that of DC04 carbon steel. The choice of laser welding parameters (primarily, laser power and beam speed) significantly impacted the weld structure and properties.

3

Influence of sodium and potassium formate on the ASR reactivity of granite aggregate

Antolik Aneta

Structure and Environment

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2022

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Vol. 14, no. 3

69--75

EN

Use of de-icing agents is necessary in winter to maintain appropriate quality of road and airport surfaces. Formate or acetate de-icing agents are safer for aircraft and the environment than the commonly used sodium chloride, but may cause an alkali-silica reaction in concrete. The study investigated the influence of sodium formate and potassium formate on the occurrence of ASR (alkali-silica reaction) in mortars with granite aggregate. Accelerated mortar-bar tests at 80°C using various de-icing agents were performed and detailed studies of the SEM-EDS microstructure were carried out.

PL

Stosowanie środków odladzających jest niezbędne do zimowego utrzymania odpowiedniej jakości betonowych nawierzchni drogowych i lotniskowych. Środki odladzające na bazie mrówczanów lub octanów są bezpieczniejsze zarówno dla środowiska, jak i statków powietrznych niż powszechnie stosowany chlorek sodu, jednak mogą wywoływać reakcję alkaliczno-krzemionkową kruszywa w betonie. W pracy analizowano wpływ mrówczanu sodu i mrówczanu potasu na potencjał wystąpienia ASR (alkali-silica reaction) w zaprawach z kruszywem granitowym. Przeprowadzono badania ekspansji w 80°C z zastosowaniem różnych środków odladzających oraz przeprowadzono szczegółowe badania mikrostruktury SEM-EDS.

4

Strukturalne aspekty korozji zmęczeniowej ocynkowanych elementów złącznych

Lachowicz Maciej B., Lachowicz Marzena M.

Ochrona przed Korozją

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2022

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nr 5

140--145

PL

W pracy przedstawiono wyniki badań mikrostrukturalnych zerwanej śruby stosowanej w sprężonych złączach doczołowych. Celem badań była ocena wpływu mikrostruktury powłoki cynkowej na proces korozji. Stwierdzono, że eksploatacji elementów ocynkowanych w środowisku korozyjnym towarzyszy zarodkowanie pęknięć w powłoce cynkowej. Powstałe pęknięcia stają się karbami spiętrzającymi naprężenia, co w warunkach oddziaływań obciążeń mechanicznych może ułatwiać inicjację pęknięć zmęczeniowych. W konsekwencji część z nich rozwija się w pęknięcia w podłożu stalowym, stanowiące przedłużenie pęknięć zainicjowanych w powłoce cynkowej. Ich obecność zmniejsza długość pęknięcia wymaganą do osiągnięcia krytycznego wymiaru prowadzącego do dalszego rozprzestrzeniania się pęknięcia na całym przekroju stalowego elementu. Pęknięcia propagują w głąb materiału w obszarze wrębów gwintu, które są makroskopowymi koncentratorami naprężeń w śrubie. Dowodzi to także istotnej roli naprężeń w dalszym rozprzestrzenianiu się tych mikropęknięć.

EN

The paper presents the results of microstructural tests of a broken bolt used in prestressed butt joints. The aim of the research results presented in this paper is to emphasize the role of the microstructure of the zinc coating on the corrosion process. It was found that the exploitation of galvanized elements in a corrosive environment is accompanied by nucleation of cracks in the zinc coating. The resulting cracks become notches that accumulate stresses, which, under the influence of mechanical loads, may facilitate thei nitiation of fatigue cracks. Consequently some of them develop into cracks in the steel substrate, which are extensions of the cracks initiated in the zinc coating. They reduce thecrack length required to achieve a critical dimension leading to further crack propagation over the entire cross section of the steel member. Cracks propagate deep into the material in the area of the thread grooves, which are macroscopic stress concentrators in the bolt. It also proves the important role of stress in the further propagation of these microcracks.

5

Porównanie mikrostruktury i odporności na korozję powłok natryskiwanych metodą HVOF (high velocity oxy fuel) na podłoże ze stopu magnezu

Jaworska Justyna, Gruszka Magdalena, Nabrdalik Monika, Marcinkowski Marcin, Mikołejko Wojciech, Augustyn Ewelina, Jonda Ewa, Maciej Artur, Kiljan Anna

Ochrona przed Korozją

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2022

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nr 4

112--123

PL

Stopy magnezu ze względu na korzystny stosunek niskiej masy do dobrych własności mechanicznych coraz powszechniej są stosowane w przemyśle. Przeszkodę w ich aplikacji może stanowić reaktywność chemiczna magnezu, a więc jego wysoka podatność na korozję. Powłoki natryskiwane cieplnie metodą HVOF (high velocity oxy fuel) pozwalają wytworzyć szczelną barierę pomiędzy materiałem podłoża a środowiskiem, dzięki czemu mogą stanowić skuteczną ochronę stopów magnezu. W artykule przedstawiono wyniki badań mikrostruktury oraz wybranych własności dwóch powłok natryskiwanych przy wykorzystaniu komercyjnych proszków WC-Co i WC-Cr3C2-Ni metodą HVOF na podłożu ze stopu magnezu AZ91. Celem pracy było porównanie mikrostruktury, wybranych własności oraz odporności na korozję wytworzonych powłok. Na podstawie wyników badań mikroskopowych stwierdzono, że powłoki charakteryzują się zwartą mikrostrukturą, a twarde cząstki WC oraz Cr3C2 są równomiernie rozłożone w całej objętości powłoki. Powłoka WC-Co charakteryzuje się ponadto wyższą odpornością korozyjną oraz mikrotwardością, jednak cechuje ją mniejsza wydajność natryskiwania i chropowatość w porównaniu z powłoką WC-Cr3C2-Ni.

EN

Due to the promising ratio of low weight to good mechanical properties, magnesium alloys are more and more widely used in industry. An obstacle in their application may be the chemical reactivity of magnesium, and therefore its high susceptibility to corrosion. Thermal sprayed coatings with the HVOF (high velocity oxy fuel) method allow creating a tight barrier between the base material and the environment, which can effectively protect magnesium alloys. The article presents the results of research on the microstructure and selected properties of two sprayed coatings with the use of commercial WC-Co and WC-Cr3C2-Ni powders using the HVOF method on the substrate made of AZ91 magnesium alloy. The work aimed to compare the microstructure, selected properties, and corrosion resistance of the produced coatings. Based on the results of the metallographic research, it was found that the coatings are characterized by a dense microstructure, and the hard particles of the WC and Cr3C2 are evenly distributed throughout the entire volume of the coating. Also the WC-Co coating is characterized by higher corrosion resistance and microhardness however, it has a lower spray efficiency and roughness compared to the WC-Cr3C2-Ni coating.

6

Wpływ przyspieszonego starzenia na mikrostrukturę i wybrane właściwości mechaniczne profili z kompozytów polimerowych zbrojonych łuskami zbóż

Kozikowska Ewelina, Sudoł Ewa

Materiały Budowlane

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2022

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nr 9

76--79

PL

Analizowano wpływ czynników atmosferycznych na przebieg starzenia kompozytów polimerowych zbrojonych włóknami lignocelulozowymi, które zostały pozyskane z łusek roślin uprawnych. Poddanie profili kompozytowych procesowi starzenia wyraźnie zmienia morfologię powierzchni. Analiza mikrostruktury powierzchni zewnętrznych uwidoczniła przetopienia wierzchniej warstwy osnowy polimerowej prowadzące do odsłonięcia powierzchni cząstek wypełniacza. Przeprowadzone badania wykazały najlepsze właściwości użytkowe profili z dodatkiem łusek owsa w stanie wyjściowym oraz po starzeniu, których właściwości były porównywalne z komercyjnymi profilami zbrojonymi łuskami ryżowymi.

EN

The influence of atmospheric factors on ageing of polymer composites reinforced with lignocellulose fibers has been analysed. Three natural fibers obtained from the husks of cultivated plants: rice, oat, millet husk were used as fillers. The microscopic analysis of the surfaces revealed melting of the top layer of the polymer matrix, leading to the exposure of the filler particles. The carried out mechanical tests showed the best properties for profiles with oat hulls in the initial state and after ageing, whose properties were comparable to those of commercial profiles reinforced with rice hulls.

7

Podstawowe właściwości geopolimerów z dodatkiem odpadu ceramicznego

Chuczun Aleksandra, Rakowski Bartosz, Gosk Edyta, Kalinowska-Wichrowska Katarzyna

Materiały Budowlane

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2022

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nr 8

80--83

PL

W artykule przedstawiono podstawowe właściwości geopolimerów z dodatkiem miału ceramicznego, tj.: wytrzymałość na zginanie i ściskanie, nasiąkliwość wagową, gęstość objętościową. Wykonano analizę SEM kompozytów i badania chemiczne surowców. Przyjęto stałą zawartość dodatku odpadowego, zmienną temperaturę wygrzewania i zawartość aktywatora. Wyniki wskazują na korzystny wpływ dodatku miału ceramicznego na badane cechy kompozytów.

EN

The article presents the basic properties of geopolymers with the use of ceramic fines, i.e. flexural and compressive strength, water absorption, bulk density. SEM analysis of composites and chemical tests of research raw materials were performed. A constant content of waste additive, a variable curing temperature and activator content were assumed. The results show a beneficial effect of the addition of ceramic fines on the examined properties of the composites.

8

Odporność profili budowlanych z kompozytów polimerowych zbrojonych łuskami zbóż na grzyby domowe

Sudoł Ewa, Kozikowska Ewelina, Goron Maria

Materiały Budowlane

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2022

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nr 9

70--75

PL

Analizowano odporność profili z kompozytów PVC z napełniaczem z pulweryzowanych łusek owsa, prosa i ryżu na działanie na grzybów domowych. Wyroby z łuskami owsa i ryżu wykazały porównywalną podatność na działanie Coniophora puteana, Gloeophyllum trabeum oraz Coriolus versicolor, ale mniejszą niż kompozyt z łuskami prosa. Coniophora puteana wykazał największy stopień rozwoju grzybni i zmienił morfologię powierzchni profili. Ekspozycja na działanie grzybów w środowisku mokrym skutkowała zmniejszeniem wytrzymałości na zginanie i modułu sprężystości, największym w przypadku kompozytu zbrojonego łuskami prosa. Kluczowy był wpływ samego środowiska mokrego. Mikroorganizmy nieznaczenie zmieniły właściwości przy zginaniu.

EN

The resistance to fungi of oat, millet and rice husks reinforced PVC composite profiles was analysed. Products with oat and rice husks showed comparable susceptibility to Coniophora puteana, Gloeophyllum trabeum and Coriolus versicolor, lower than the composite with millet husks. Coniophora puteana showed the highest degree of mycelium growth, changing the morphology of the profile surface. Exposure to fungi in a wet condition caused a decrease in flexural strength and modulus of elasticity, the greatest in the case of millet husks reinforced composite. The influence of the wet conditions itself was crucial. The microorganisms slightly changed the bending properties.

9

Ocena właściwości zapadowych lessowego podłoża gruntowego

Kokoszka Wanda

Materiały Budowlane

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2022

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nr 11

126--128

PL

Atrakcyjność gospodarcza i turystyczna obszarów lessowych sprawia, że są one intensywnie wykorzystywane w celu realizacji inwestycji budowlanych, zarówno kubaturowych, jak i liniowych. Warunki podłoża budowlanego zbudowanego z utworów lessowych są jednak uznawane za niekorzystne przede wszystkim z powodu dużej wrażliwości na zmiany zawilgocenia. W pracy przedstawiono problematykę procesów deformacyjnych w tych gruntach z uwzględnieniem analizy mikrostrukturalnej. Przeanalizowano zastosowanie wybranych kryteriów pośrednich i bezpośrednich do oceny właściwości zapadowych na przykładzie badania lessów z rejonu Rzeszowa.

EN

The economic and tourist attractiveness of loess areas means that they are intensively used for construction investments, both cubature and linear. However, the conditions of the construction substrate made of loess formations are considered unfavorable mainly due to high sensitivity to changes in moisture. The paper presents the problems of deformation processes in these soils, taking into account the microstructural analysis. The application of selected direct and indirect criteria for the assessment of collapsing properties has been analyzed on the example of loess research in the Rzeszów region.

10

Role of Si on machined surfaces of Al-based automotive alloys under varying machining parameters

Razin Ahmed Asif, Ahammed Dewan Salsabil, Nur Maglub Al, Kaiser Mohammad Salim

Journal of Mechanical and Energy Engineering

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2022

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Vol. 6, No 1

43--52

EN

A morphological change due to Si contend into Al-based automotive alloys has been conducted on the characterization of machined surfaces in terms of roughness, temperature, chips formation as well as microstructure evaluation under different machining conditions. For this experiment, a shaper machine with HSS single point V-shaped cutting tool is used at different cutting speeds and depths of cut. The experimental results show that the surface roughness of the alloys decreases with the cutting speed and depth of cut but it is more prominent in the case of the cutting speed. This is because of a high cutting speed, which is more associated with the higher temperature and softening the work material leading to better surface finish. Higher Si added alloys also exhibit a better surface finish because the sample content is different fine and hard intermetallic due to ageing treatment, which also makes the alloys more brittle. For brittle and higher hardness, it produces a higher temperature during machining. During machining, relatively curly and short chips are formed by the high Si added alloy because of its low elongation properties. The fracture surfaces of higher Si added alloy display more crack propagation obtained by plate-like Si rich intermetallic.

11

HA-ZnO-Fe3O4 composite manufactured by wet powder metallurgy process for implant applications

Gupta Ruchi, Agarwal Mayank, Singh Vinay Pratap

Composites Theory and Practice

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2022

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R. 22, nr 1

40--43

EN

A hydroxyapatite (HA) based biocompatible and bioactive composite is an appropriate choice for bio-implants. This experimental work presents the influence of ZnO and Fe3O4 on the microstructure of HA-ZnO-Fe3O4 composites synthesized by the wet powder metallurgy process. These composites were characterized using SEM, energy-dispersive X-ray spectroscopy (EDS), and XRD. The obtained results showed the effect of the addition of Fe3O4 on the interface formation, which is exhibited by interconnected pores and sintered neck in the micrographs. The observed porosity helps to enhance the required osseointegration for the fixation of implants with human bones.

12

Aggregate Type Influence on Microstructural Behavior of Concrete Exposed to Elevated Temperature

Belkadi Ahmed Abderraouf, Kessal Oussama, Bensalem Sara, Aggoun Salima, Amouri Chahinez, Khouadjia Mohamed Lyes Kamel

Civil and Environmental Engineering Reports

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2022

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Vol. 32, no. 1

19--42

EN

Exposure of concrete to high temperatures affects its mechanical properties by reducing the compressive strength, bending… etc. Factors reducing these properties have been focused on by several studies over the years, producing conflicting results. This article interested an important factor, that is the type of aggregates. For this, an experimental study on the behavior of concrete based on different types of aggregates: calcareous, siliceous and silico-calcareous subjected to high temperatures. In addition, the particle size distribution of the aggregates was chosen to be almost identical so that the latter does not affect the behavior of the concrete. Aggregates and concrete samples were subjected to a heating/cooling cycle of 300, 600 and 800°C at a speed of 1°C/ min. The mechanical and physical properties of concrete before and after exposure to high temperatures were studied. In addition, a microstructural study using a scanning electron microscope and a mercury porosimeter was performed. Thus, a comparative study between various researches on the mechanical properties of concrete exposed to high temperatures containing different types of aggregates was carried out. The compressive strength test results showed that the concrete based on siliceous aggregates (C-S) has better mechanical performance up to 300°C. However, above 300°C, the compressive strength decreases faster compared to calcareous-based concrete (C-C). According to the mercury porosimeter test, at 600°C, C-SC and C-S concretes have the highest number of pores compared to C-C concretes. The microstructure of concrete at high temperatures was influenced mainly by the aggregate’s types and the paste-aggregate transition zone. This study reinforces the importance of standardizing test procedures related to the properties of concrete in a fire situation so that all the results obtained are reproducible and applicable in other research.

13

Wpływ rodzaju kruszywa na opóźnione powstawanie ettringitu

Owsiak Zdzisława

Cement Wapno Beton

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2022

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R. 27, nr 2

144--151

PL

Przeprowadzone badania miały na celu oznaczenie wpływu rodzaju kruszywa na równoczesne występowanie reakcji wodorotlenków sodu i potasu z krzemionką w kruszywie i opóźnionego powstawania ettringitu. Stosowano piasek lub kruszywo wapienne oraz kruszywo zawierające 6% opalu, o uziarnieniu od 0,5 do 1,0 mm. Przygotowano zaprawy z tymi rodzajami kruszywa i z cementem portlandzkim, zawierającym 1,2% Na2Oe i 4,5% SO3, które dojrzewały w 90°C i w wodzie. Badania potwierdziły duży wpływ rodzaju kruszywa, na rozszerzalność spowodowaną opóźnionym powstawaniem ettringitu. Po tych warunkach dojrzewania kruszywo wapienne w znacznym stopniu zmniejszyło ekspansję zaprawy, spowodowaną opóźnionym powstawaniem ettringitu, natomiast miało znacznie mniejszy wpływ na ekspansję beleczek, spowodowaną przez reakcję wodorotlenku potasu z opalem. Obserwacje mikrostruktury zaprawy wykazały, że żel sodowo-potasowo-wapienny, a także ettringit otaczający ziarna kruszywa, są odpowiedzialne za ekspansję w przypadku piasku z dodatkiem opalu.

EN

The studies carried out aimed to define the influence of the aggregate type on the simultaneous occurrence of the alkali-silica reaction and delayed ettringite formation. In their composition, sand or calcium aggregate and aggregates containing 6% opal with graining of 0.5 to 1.0 mm, were used. Mortars from each type of aggregate and Portland cement containing 1.2% Na2Oe and 4.5% SO3 were prepared, and then cured in water at 90°C. Studies have shown a great influence of the type of aggregate on the expansion caused by the delayed ettringite formation. In this case, the calcium aggregate visibly reduces the expansion of a mortar caused by delayed ettringite formation, while it has a much smaller influence on the expansion of the bars, caused by the potassium reaction with opal. Microstructure observations have shown that sodium-potassium-calcium silicate gel and ettringite around the aggregate grains, are responsible for expansion in the case of sand with opal addition.

14

The Effect of Sulphur Content on the Microstructure of Vermicular Graphite Cast Iron

Mróz M., Orłowicz A. W., Tupaj M., Lenik M., Kawiński M., Kawiński M.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 1

18--22

EN

The application of ferritic-matrix vermicular graphite cast iron in the production of fireplace fireboxes improves their thermal output, but the consumer market for these products prioritises their price. Given this consideration, this work concerns a comparison of the quality of vermicular graphite cast iron types produced from 0.025%S pig iron (a less expensive material) and 0.010%S pig iron (a more expensive material) in terms of the number and shape of vermicular graphite precipitates varying with the magnesium level in the alloy. It turned out that the vermicular graphite cast iron made with the 0.025%S pig iron demonstrated a slightly lower number of vermicular graphite precipitates. For both vermicular graphite cast iron melts, 0.028%Mg and 0.020%Mg in the alloys provided a vermicular graphite precipitate share of approx. 50% and 95%, respectively.

15

Mechanical and Microstructural Characterization of Aluminium Alloy, EN AC-Al Si12CuNiMg

Sirata Gotfila G., Wacławiak K., Dyzia Maciej

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 3

34--40

EN

the manufacture of mechanical structures where low weight is critical. However, when these alloys are subjected to elevated temperatures, their mechanical properties deteriorate significantly. The aim of this study is to investigate the effect of temperature on the mechanical properties of aluminium alloy, EN AC-Al Si12CuNiMg. For this purpose, an experimental investigation was performed at ambient and elevated temperatures on aluminium alloy samples prepared by casting. Tensile and hardness tests were carried out to characterize the mechanical properties of this material. Additionally, an optical microscope was used to examine the microstructures of this alloy. Finally, a scanning electron microscope was used to analyze the fracture modes of this material. The results show that the mechanical properties such as tensile strength, yield strength, and Young's modulus of this alloy dramatically decrease when the temperature exceeds 250oC. The microstructural investigation reveals several factors that are detrimental to the mechanical properties of this alloy. This includes coarse-grained structures, micro-pores, and several intermetallic compounds. Furthermore, fractography reveals a minor cleavage-like pattern and micro-cracks on the fracture surface of all failed samples under various temperatures, indicating semi-brittle fracture mode.

16

Corrosion Behavior of FeAl and Fe3Al Based Fe-Al-C Alloys in Sulfuric Acid

Silva A. P., Brito P. P., Martins N.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 2

77--82

EN

Iron aluminides are iron-aluminum alloys that have excellent resistance to oxidation at high temperatures with low density, high resistance/weight ratio and a low manufacturing cost. Due to its characteristics, these alloys are presented as an option to replace stainless steels in certain applications. This works intends report the casting process and subsequent analyses involving microstructure, mechanical properties, and corrosion resistance of two Fe-Al-C alloys (Fe-11wt%Al and Fe-25wt%Al, containing 0.31-0.37%C), which were prepared in an induction furnace and poured in a permanent mold. Samples of these alloys were characterized and presented elevated hardness values of 37 HRC (alloy Fe-11wt%Al) and 49.6HRC (alloy Fe-25wt%Al) and microstructure with aluminides type Fe3Al and FeAl and also carbides type K. The Fe-11wt%Al alloy exhibited superior resistance to uniform corrosion, although both Fe-Al-C alloys exhibited significantly higher corrosion rates compared to a binary iron aluminide in 0.5M H2SO4 containing naturally dissolved oxygen.

17

Characterization of ultrafine-grained copper joints acquired by rotary friction welding

Ciemiorek M., Morawiński Ł., Jasiński C., Orłowska M., Chmielewski T., Olejnik L., Lewandowska M.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no 1

art. no. e9, 2022

EN

Copper rods with ultrafine-grained microstructure, obtained by multi-turn ECAP processing, were subjected to Direct Drive Rotary Friction Welding using various processing parameters, such as rotational speed and pressure, which resulted in different energy and heat input. Even though friction welding is a high energy process, by a proper selection of processing parameters it was possible to maintain grain size at around 0.7 µm in the weld zone and preserve the UFG microstructure. These microstructural features translated into mechanical properties: the YS for those specimens was around 330 MPa. Processing parameters that resulted in a larger heat input caused an increase in grain size to around 2 µm; this, however, increased ductility and led to a uniform elongation exceeding 5%. Corrosion resistance in the stir zone increased, as was evident in the higher open circuit potential and higher corrosion potential in comparison with base material; the observed differences were about 50 mV. These changes can be explained by the higher fraction of HAGBs in the SZ.

18

The effect of resistance spot welding parameters on microstructure and strength of DP800 steel joints using response surface methodology

Rajarajan Chakkravarthi, Sonar Tushar, Sivaraj Paramasivam, Raja Selvaraj, Mathiazhagan Nallusamy

Advances in Materials Science

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2022

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Vol. 22, nr 3(73)

53--78

EN

The main objective of this paper is to analyze the direct and interaction effect of resistance spot welding (RSW) parameters on microstructure and strength of DP800 steel joints using response surface methodology (RSM). The DP800 steel sheets were spot welded in straight lap and cross lap joint configuration using RSW. The relationship between the RSW parameters, tensile shear fracture load (TSFL) and nugget zone hardness (NZH) was established employing statistical regression analysis and validated using Analysis of Variance (ANOVA). The DP800 steel joints made using welding current of 5.0 kA, electrode pressure of 4.0 MPa, and welding time of 1.50 s displayed maximum STRAIGHT-TSFL of 21.7 kN, CROSS-TSFL of 17.65 kN, and NZH of 589 HV0.5 respectively.

19

Microstructure and mechanical properties of Sc-modified AA2519-T62 laser beam welded butt joints

Kosturek Robert, Grzelak Krzysztof, Torzewski Janusz, Wachowski Marcin, Śnieżek Lucjan

Advances in Materials Science

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2022

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Vol. 22, nr 4(74)

57--69

EN

The fundamental aim of the research is to investigate the microstructure and mechanical properties of the AA2519-T62 laser beam welded joints obtained with various values of welding velocity. For the constant value of laser power (3.2 kW) three joints have been produced with various values of welding velocity: 0.8, 1.1, and 1.4 m/min. The joints have been subjected to microstructure analysis (including both light and scanning electron microscope), microhardness measurements, tensile tests, and fractography of tensile samples. The established values of joint efficiency contain within the range of 55-66% with the highest value (66%) reported for the joint obtained with 1.1 m/min welding velocity. The produced welds have noticeable participation of pores, which tends to increase together with the value of welding velocity. In all cases, the failure has occurred in the fusion zone by ductile fracture.

20

Effects of B addition on the microstructure and microhardness of melt-spun Al-7075 alloy

Kilicaslan Muhammed Fatih, Elburni Saad Ibrahim, Yilmaz Yasin, Akkaş Mehmet

Advances in Materials Science

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2022

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Vol. 22, nr 2(72)

5--18

EN

Main aim of this study is to examine change of microstructural and the mechanical properties of Al-7075 alloy depending on B content added with different proportions. Rapid solidification process used to produce the alloys was carried out with a single roll melt spinner via a wheel with a rotational speed of 25 m/s. For the microstructural characterization of the alloys, a scanning electron microscope and X-ray diffraction analyzes were used. According to obtained results, it can be said that B addition led to modification of dimensions and shapes of both α−Al and intermetallic phases occurred, it reduced average grain size from 0.45 μm to 0.34 μm in the microstructure. The B addition also led to dramatically increase in microhardness of the Al-7075 alloy. The microhardness of the alloy with 0.4 wt. % B is 0.19 GPa, this is clearly one times higher than that of the alloy without B addition. The microhardness of the alloy with 1 wt. % B is 0.21 GPa, this is also slightly higher than that of the alloy with 0.4 wt. % B.