11. Effects of variated final temperature and workpiece thickness for hot rolling of aluminum alloy EN AW-8011Jakob Kraner, Peter Cvahte, Primož Šuštarič, Tomaž Šuštar, Črtomir Donik, Irena Paulin, Shae K. Kim, Kjung Il Kim, 2023, izvirni znanstveni članek Ključne besede: aluminum alloy, hot rolling, simulations, metallography, mechanical properties
Objavljeno v DiRROS: 01.02.2024; Ogledov: 165; Prenosov: 87
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12. Improving the surface properties of additive-manufactured Inconel 625 by plasma nitridingDanijela Anica Skobir Balantič, Črtomir Donik, Bojan Podgornik, Aleksandra Kocijan, Matjaž Godec, 2023, izvirni znanstveni članek Povzetek: As a surface-hardening technique, plasma nitriding is a common procedure for improving the properties of
conventional Ni-based alloys. The diffusion of nitrogen hardens a layer on the surface of the alloy, leading to
better wear resistance and a higher coefficient of friction, as well as a higher surface hardness. This study reports
the effect of plasma nitriding on additive-manufactured (AM) Inconel 625 (IN625) compared to its conventional
manufactured and nitrided counterparts. The samples produced with the laser powder-bed fusion (LPBF) process
were subsequently plasma nitrided in the as-built condition, stress-relief annealed at 870 °C and solution treated
at 1050 °C. The plasma nitridings were carried out at 430 °C and 500 °C for 15 h. The growth kinetics of the
nitride layer of the AM samples depends on the prior heat treatments and is faster in the as-built state due to the
specific cellular structure. The lower nitriding temperature leads to the formation of expanded austenite in the
nitride layer, while at the higher nitriding temperature, the expanded austenite decomposes and CrN precipitation
occurs. The XRD and SEM analyses confirmed the presence of two layers: the surface layer and the
diffusion layer beneath. The lower nitriding temperature caused the formation of expanded austenite or a
combination of expanded austenite and CrN. The higher nitriding temperature led to the decomposition of the
expanded austenite and to the formation/precipitation of CrN. The higher nitriding temperature also decreased
the corrosion resistance slightly due to the increased number of precipitated Cr-nitrides. On the other hand, the
wear resistance was significantly improved after plasma nitriding and was much less influenced by the nitriding
temperature.
Ključne besede: additive manufacturing, powder-bed fusion, plasma nitriding, expanded austenite, wear and corrosion resistance, Ni-based alloy
Objavljeno v DiRROS: 31.01.2024; Ogledov: 205; Prenosov: 84
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13. The corrosion resistance of dental Ti6Al4V with differing microstructures in oral environmentsMirjam Bajt Leban, Tadeja Kosec, Matjaž Finšgar, 2023, izvirni znanstveni članek Povzetek: The impact of the microstructural properties of a Ti6Al4V alloy on its electrochemical properties, as well as the effect of the α- and β-phases present within it, is still unclear. With the introduction of new, emerging technologies, such as selective laser melting and post heat treatments, the effect of the microstructure on an alloy's corrosion properties has become increasingly interesting from a scientific perspective. When these alloys are produced through different methods, despite an identical chemical composition they have diverse microstructures, and consequently display varying resistance to corrosion. In the present research study, Ti–6Al–4V alloy specimens produced by three different processes, leading to the formation of three different microstructures were investigated: heat treated specimen fabricated by selective laser melting, wrought and cast specimens. The impact of the microstructure of these alloys when immersed in artificial saliva was studied through the use of various electrochemical techniques, by microscopical examinations, and time-of-flight secondary ion mass spectrometry. Corrosion properties were investigated by the measurement of open circuit potential, linear polarization, and potentiodynamic curve measurements followed by microscopical examinations, and time-of-flight secondary ion mass spectrometry examination was conducted to reveal spatial distribution of alloying species on oxide film. It was found that the difference between specimens containing an α+β microstructure was small and not dependent on the aspect ratio of the β-phase, alloy grain size, and vanadium partitioning coefficient, but rather on the size, shape, and content of this phase.
Ključne besede: Ti6Al4V, dental alloy, microstructure, corrosion resistance, heat treatment, ToF-SIMS
Objavljeno v DiRROS: 26.10.2023; Ogledov: 477; Prenosov: 236
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14. Influence of laser colour marking on the corrosion properties of low alloyed TiTadeja Kosec, Andraž Legat, Janez Kovač, Damjan Klobčar, 2019, izvirni znanstveni članek Povzetek: In the field of surface treatment, laser colour marking can be used to produce coloured marks on the surfaces of metals. Laser colour markings can be applied to various materials, but on titanium alloys a wide spectra of vivid colours can be achieved. This study presents an analysis of the corrosion properties of laser treated surfaces that were exposed to aggressive environments. Different samples were prepared with laser light of various power intensities and processing speeds. The samples were prepared on low alloyed Ti. Electrochemical, spectroscopic and microstructural analyses were conducted in order to study the properties of the laser treated surfaces. Corrosion testing showed different effects of laser power and production speed on the properties of the laser treated surfaces. It was shown that a high intensity and slow processing rate affect the surfaces by forming oxides that are relatively stable in a corrosive environment of 0.1 M NaCl. Spectroscopic investigations including scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses showed the differences in chemical structure of the surface layer formed after laser treatment. Similarly, microstructural investigations showed different effects on the surface and sub-surface layer of the laser treated samples.
Ključne besede: Ti alloy, laser treatment, XPS, corrosion
Objavljeno v DiRROS: 25.10.2023; Ogledov: 389; Prenosov: 159
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15. Effect of surface machining on the environmentally-assisted cracking of Alloy 182 and 316L stainless steel in light water reactor environments : results of the collaborative project MEACTOSMariia Zimina, Stefan Ritter, Bojan Zajec, Marc Vankeerberghen, Liberato Volpe, Anna Hojna, Rik-Wouter Bosch, Fabio Scenini, Zaiqing Que, Alberto Sáez-Maderuelo, P. Jill Meadows, Michael Grimm, Matthias Herbst, Andraž Legat, Agostino Maurotto, Radek Novotny, Karl-Heinz Seifert, 2023, izvirni znanstveni članek Povzetek: The main objective of the EU-funded project mitigating environmentally-assisted cracking through optimisation of surface condition (MEACTOS) was to gain knowledge on the ability of different surface machining procedures to mitigate environmentally-assisted cracking (EAC) in typical light water reactor structural materials and environments. Surfaces of cold-worked (CW) type 316L austenitic stainless steel and nickel-based weld metal Alloy 182 flat tapered tensile specimens were machined using different processes. EAC initiation susceptibility of these specimens was evaluated using constant extension rate tensile (CERT) tests under simulated boiling water reactor (BWR) and pressurized water reactor (PWR) conditions and assessed using constant load experiments. More than a hundred tests were performed covering about 10 years of autoclave testing time. Only minor or no measurable improvements in EAC initiation susceptibility as a function of surface treatments (grinding or advanced machining) compared to the standard industrial face milling were demonstrated. In most cases, the stress thresholds for EAC initiation determined in constant load tests confirmed the trend obtained from CERT tests. This paper summarises the most important results and conclusions concerning the EAC initiation behaviour for the CW 316L and Alloy 182 under reducing PWR and oxidizing BWR conditions.
Ključne besede: crack initiation, environmentally-assisted cracking, Alloy 182, AISI 304 stainless steel, surface treatment, light water reactor, open access
Objavljeno v DiRROS: 30.05.2023; Ogledov: 343; Prenosov: 195
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16. Differences between 3-D printed and traditionally milled CoCr dental alloy from casted block in oral environmentMirjam Bajt Leban, Matej Kurnik, Igor Kopač, Matic Klug Jovičević, Bojan Podgornik, Tadeja Kosec, 2023, izvirni znanstveni članek Povzetek: The aim of this study was to compare corrosion resistance and ion release in CoCr dental alloys with identical chemical compositions produced using different technologies (SLM – selective laser melting and milling from cast blocks) and heat treatment (SLM parts only). The corrosion properties were tested in artificial saliva, artificial saliva with fluoride ions, and artificial saliva with added lactic acid to simulate inflammations. The study included electrochemical tests, microstructural investigation and ion release tests in the three different environments for a total of 42 days. The best performance of CoCr as a result of potentiodynamic polarization was observed in the artificial saliva with added lactic acid, which is in contradiction with the highest ion release measured from all the materials tested and electrochemical impedance spectroscopy that showed a deterioration of the passive layer in an acidic environment. Microstructural investigation revealed that different phases precipitated by heat treatment trigger increased release of Mo and W ions. The printing method does not raise critically ion release from CoCr alloy, while the state of the surface greatly impacts the extent of the ion release. This study demonstrates the importance of an interdisciplinary approach to the study of corrosion and biocompatibility in dental alloys.
Ključne besede: CoCr dental alloy, selective laser melting, corrosion, ion release, artificial saliva
Objavljeno v DiRROS: 29.05.2023; Ogledov: 347; Prenosov: 294
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17. Investigation of surface treatment effects on the environmentally-assisted cracking behaviour of Alloy 182 in boiling water reactor environmentZaiqing Que, Bojan Zajec, Stefan Ritter, Tommi Seppänen, Timo Saario, Aki Toivonen, Aleksandra Treichel, Valentin Lautaru, Fabio Scenini, 2022, izvirni znanstveni članek Povzetek: Surface treatments of primary circuit components in light water reactors are regarded as possible ways to mitigate environmentally-assisted cracking (EAC). To date, it is not fully conclusive which surface condition is suitable to reduce the EAC initiation susceptibility. Constant extension rate tensile (CERT) tests were performed by several labs using flat tapered tensile specimens with different surface conditions (ground, industrial face milled, advanced face milled and shot peened), exposed to a boiling water reactor normal water chemistry environment at 288°C. Despite some scatter in the results, the CERT tests revealed that the EAC initiation susceptibility seems lowest for the advanced face milled surface and highest for the shot peened surface. However, it must be emphasised that the differences were moderate and that the surprising behaviour of the shot peened surface can be explained. The mechanical grinding of the surface did not significantly retard EAC initiation compared to industrial face milling.
Ključne besede: crack initiation, environmentally-assisted cracking, Alloy 182, surface machining, boiling water reactor, open access
Objavljeno v DiRROS: 05.05.2023; Ogledov: 364; Prenosov: 153
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18. Thermal-deformation model of a SR-modified A356 aluminum alloyYongyue Liu, Xianglai Xu, Jiangxiong Cheng, Hongwei Sun, Xueping Ren, Peng Jiang, 2022, izvirni znanstveni članek Ključne besede: A356 aluminum alloy, Sr modification, microstructure, thermal-deformation model
Objavljeno v DiRROS: 22.06.2022; Ogledov: 534; Prenosov: 157
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20. Structural and elastic properties of AgNi[sub]10 alloy studied with ab-initio calculationsJide Liu, Xue Wang, Xiaoming Du, Ming Xie Xie, Jinguo Li, Shangqiang Zhao, Yizhou Zhou, Qiao Zhang, Jiheng Fang, 2022, izvirni znanstveni članek Ključne besede: AgNi[sub]10 alloy, ab initio calculations, elastic anisotropy, thermodynamic properties
Objavljeno v DiRROS: 22.06.2022; Ogledov: 583; Prenosov: 145
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