TY  - JOUR
AU  - Musrati, Walid
AU  - Međo, Bojan
AU  - Cvijović-Alagić, Ivana
AU  - Gubeljak, Nenad
AU  - Štefane, Primož
AU  - Radosavljević, Zoran
AU  - Rakin, Marko
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11325
AB  - Steel pipelines in industrial plants consist of different elements, including seamless and/or welded (seam) pipes. Properties of welded pipes, including their fracture behaviour, depend on the characteristics of both, the base metal, and the weld metal. In this work, two seam pipes are considered having different diameters and manufactured of P235TR1 steel. Hardness and microstructure were examined on the samples which contained the seam zone, to capture the influence of heterogeneity. Fracture resistance of the pipeline material, i.e. of both base metals and both seams, was determined by experimental examination of the recently proposed Pipe ring notch bending specimens with sharp stress concentrators. Differences between the two tested pipes, including the influence of the heterogeneity caused by the welded joint, were determined by comparison of the crack growth resistance curves. Effects of the initial stress concentrator shape, sharp machined notch or fatigue pre-crack are discussed.
AB  - Čelični cevovodi u industrijskim postrojenjima se sastoje od različitih elemenata, uključujući bešavne i/ili zavarene (šavne) cevi. Osobine šavnih cevi, uključujući ponašanje materijala cevi pri lomu, zavise i od osnovnog metala i od metala šava. U ovom radu razmatrane su dve šavne cevi različitih prečnika, izrađene od čelika P235TR1. Tvrdoća i mikrostruktura su analizirane na uzorcima isečenim iz cevi u zoni šava, da bi se odredio uticaj heterogenosti. Otpornost prema lomu materijala cevovoda, tj. oba osnovna metala i oba šava, je određena na osnovu ispitivanja epruveta oblika prstena sa oštrim koncentratorima napona, predloženih u prethodnim studijama. Poređenjem krivih otpornosti prema rastu prsline određene su razlike između dve ispitivane cevi, kao i uticaj heterogenosti izazvan postojanjem zavarenog spoja. Razmotren je uticaj oblika početnog koncentratora napona, oštrog žleba odnosno zamorne početne prsline.
T2  - Hemijska industrija
T1  - Microstructure, hardness and fracture resistance of P235TR1 seam steel pipes of different diameters
T1  - Otpornost prema lomu, tvrdoća i mikrostruktura šavnih cevi različitog prečnika izrađenih od čelika P235TR1
VL  - 77
IS  - 2
SP  - 155
EP  - 165
DO  - 10.2298/HEMIND230222016M
ER  - 

@article{
author = "Musrati, Walid and Međo, Bojan and Cvijović-Alagić, Ivana and Gubeljak, Nenad and Štefane, Primož and Radosavljević, Zoran and Rakin, Marko",
year = "2023",
abstract = "Steel pipelines in industrial plants consist of different elements, including seamless and/or welded (seam) pipes. Properties of welded pipes, including their fracture behaviour, depend on the characteristics of both, the base metal, and the weld metal. In this work, two seam pipes are considered having different diameters and manufactured of P235TR1 steel. Hardness and microstructure were examined on the samples which contained the seam zone, to capture the influence of heterogeneity. Fracture resistance of the pipeline material, i.e. of both base metals and both seams, was determined by experimental examination of the recently proposed Pipe ring notch bending specimens with sharp stress concentrators. Differences between the two tested pipes, including the influence of the heterogeneity caused by the welded joint, were determined by comparison of the crack growth resistance curves. Effects of the initial stress concentrator shape, sharp machined notch or fatigue pre-crack are discussed., Čelični cevovodi u industrijskim postrojenjima se sastoje od različitih elemenata, uključujući bešavne i/ili zavarene (šavne) cevi. Osobine šavnih cevi, uključujući ponašanje materijala cevi pri lomu, zavise i od osnovnog metala i od metala šava. U ovom radu razmatrane su dve šavne cevi različitih prečnika, izrađene od čelika P235TR1. Tvrdoća i mikrostruktura su analizirane na uzorcima isečenim iz cevi u zoni šava, da bi se odredio uticaj heterogenosti. Otpornost prema lomu materijala cevovoda, tj. oba osnovna metala i oba šava, je određena na osnovu ispitivanja epruveta oblika prstena sa oštrim koncentratorima napona, predloženih u prethodnim studijama. Poređenjem krivih otpornosti prema rastu prsline određene su razlike između dve ispitivane cevi, kao i uticaj heterogenosti izazvan postojanjem zavarenog spoja. Razmotren je uticaj oblika početnog koncentratora napona, oštrog žleba odnosno zamorne početne prsline.",
journal = "Hemijska industrija",
title = "Microstructure, hardness and fracture resistance of P235TR1 seam steel pipes of different diameters, Otpornost prema lomu, tvrdoća i mikrostruktura šavnih cevi različitog prečnika izrađenih od čelika P235TR1",
volume = "77",
number = "2",
pages = "155-165",
doi = "10.2298/HEMIND230222016M"
}

Musrati, W., Međo, B., Cvijović-Alagić, I., Gubeljak, N., Štefane, P., Radosavljević, Z.,& Rakin, M.. (2023). Microstructure, hardness and fracture resistance of P235TR1 seam steel pipes of different diameters. in Hemijska industrija, 77(2), 155-165.
https://doi.org/10.2298/HEMIND230222016M

Musrati W, Međo B, Cvijović-Alagić I, Gubeljak N, Štefane P, Radosavljević Z, Rakin M. Microstructure, hardness and fracture resistance of P235TR1 seam steel pipes of different diameters. in Hemijska industrija. 2023;77(2):155-165.
doi:10.2298/HEMIND230222016M .

Musrati, Walid, Međo, Bojan, Cvijović-Alagić, Ivana, Gubeljak, Nenad, Štefane, Primož, Radosavljević, Zoran, Rakin, Marko, "Microstructure, hardness and fracture resistance of P235TR1 seam steel pipes of different diameters" in Hemijska industrija, 77, no. 2 (2023):155-165,
https://doi.org/10.2298/HEMIND230222016M . .

TY  - JOUR
AU  - Barjaktarević, Dragana
AU  - Međo, Bojan
AU  - Štefane, Primož
AU  - Gubeljak, Nenad
AU  - Cvijović-Alagić, Ivana
AU  - Đokić, Veljko
AU  - Rakin, Marko
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9606
AB  - Severe plastic deformation (SPD) is a popular group of techniques applied to achieve the nanostructuring of the metallic biomaterials and improvement of their mechanical characteristics. One of the most commonly used SPD methods is the high-pressure torsion (HPT) technique which enables the obtainment of the microstructure with small grains and high strength. In the present study, the influence of the plastic deformation and surface modification treatment on the tensile and corrosion properties of the Ti–13Nb–13Zr (wt%) alloy is investigated. In that purpose, the coarse-grained (CG) Ti–13Nb–13Zr (TNZ) alloy was subjected to the HPT processing by applying a pressure of 4.1 GPa with a rotational speed of 0.2 rpm and 5 revolutions at room temperature to obtain the ultrafine-grained (UFG) microstructure. The alloy microstructure before and after HPT processing was analysed using the scanning electron microscopy (SEM) and the X-ray diffraction (XRD). The homogeneity of the UFG TNZ alloy was determined by microhardness testing and microscopic observations. The nanotubular oxide layer on the surface of the TNZ alloy, both in CG and UFG condition, was formed by electrochemical anodization in 1 M H3PO4 + NaF electrolyte for 90 min. SEM analysis was used to characterise the morphology of the anodized surfaces, while energy dispersive spectroscopy was applied to determine the chemical composition of the nanostructured layers formed at the alloy surfaces. Mechanical properties of the TNZ alloy, before and after HPT processing and electrochemical anodization, were determined by tensile testing. After tensile testing, the fractographic analysis was conducted to identify the fracture mechanisms. The potentiodynamic polarization technique was used to determine the corrosion resistance of the alloy before and after plastic deformation and surface modification treatment. The obtained results showed that the alloy is reasonably homogeneous after the HPT processing. The XRD analyses reviled the presence of α′ and β phases in the CG TNZ alloy microstructure, while the additional ω phase was detected in the microstructure of the UFG TNZ alloy. The HPT obtained alloy exhibits higher hardness and improved tensile properties than the alloy in the as-received CG condition, while the electrochemical anodization leads to a decrease of its mechanical properties. Both CG and UFG alloys show excellent corrosion stability in Ringer’s solution. Moreover, electrochemical anodization leads to a decrease or an increase of the corrosion resistance of these materials, depending on the morphology of the formed nanotubular surface layers. The results indicate that the anodized CG TNZ alloy is characterized by a lower modulus of elasticity and better corrosion resistance properties than the anodized UFG TNZ alloy. Graphic Abstract: [Figure not available: see fulltext.] © 2020, The Korean Institute of Metals and Materials.
T2  - Metals and Materials International
T1  - Tensile and Corrosion Properties of Anodized Ultrafne‑Grained
Ti–13Nb–13Zr Biomedical Alloy Obtained by High‑Pressure Torsion
VL  - 27
IS  - 9
SP  - 3325
EP  - 3341
DO  - 10.1007/s12540-020-00837-z
ER  - 

@article{
author = "Barjaktarević, Dragana and Međo, Bojan and Štefane, Primož and Gubeljak, Nenad and Cvijović-Alagić, Ivana and Đokić, Veljko and Rakin, Marko",
year = "2021",
abstract = "Severe plastic deformation (SPD) is a popular group of techniques applied to achieve the nanostructuring of the metallic biomaterials and improvement of their mechanical characteristics. One of the most commonly used SPD methods is the high-pressure torsion (HPT) technique which enables the obtainment of the microstructure with small grains and high strength. In the present study, the influence of the plastic deformation and surface modification treatment on the tensile and corrosion properties of the Ti–13Nb–13Zr (wt%) alloy is investigated. In that purpose, the coarse-grained (CG) Ti–13Nb–13Zr (TNZ) alloy was subjected to the HPT processing by applying a pressure of 4.1 GPa with a rotational speed of 0.2 rpm and 5 revolutions at room temperature to obtain the ultrafine-grained (UFG) microstructure. The alloy microstructure before and after HPT processing was analysed using the scanning electron microscopy (SEM) and the X-ray diffraction (XRD). The homogeneity of the UFG TNZ alloy was determined by microhardness testing and microscopic observations. The nanotubular oxide layer on the surface of the TNZ alloy, both in CG and UFG condition, was formed by electrochemical anodization in 1 M H3PO4 + NaF electrolyte for 90 min. SEM analysis was used to characterise the morphology of the anodized surfaces, while energy dispersive spectroscopy was applied to determine the chemical composition of the nanostructured layers formed at the alloy surfaces. Mechanical properties of the TNZ alloy, before and after HPT processing and electrochemical anodization, were determined by tensile testing. After tensile testing, the fractographic analysis was conducted to identify the fracture mechanisms. The potentiodynamic polarization technique was used to determine the corrosion resistance of the alloy before and after plastic deformation and surface modification treatment. The obtained results showed that the alloy is reasonably homogeneous after the HPT processing. The XRD analyses reviled the presence of α′ and β phases in the CG TNZ alloy microstructure, while the additional ω phase was detected in the microstructure of the UFG TNZ alloy. The HPT obtained alloy exhibits higher hardness and improved tensile properties than the alloy in the as-received CG condition, while the electrochemical anodization leads to a decrease of its mechanical properties. Both CG and UFG alloys show excellent corrosion stability in Ringer’s solution. Moreover, electrochemical anodization leads to a decrease or an increase of the corrosion resistance of these materials, depending on the morphology of the formed nanotubular surface layers. The results indicate that the anodized CG TNZ alloy is characterized by a lower modulus of elasticity and better corrosion resistance properties than the anodized UFG TNZ alloy. Graphic Abstract: [Figure not available: see fulltext.] © 2020, The Korean Institute of Metals and Materials.",
journal = "Metals and Materials International",
title = "Tensile and Corrosion Properties of Anodized Ultrafne‑Grained
Ti–13Nb–13Zr Biomedical Alloy Obtained by High‑Pressure Torsion",
volume = "27",
number = "9",
pages = "3325-3341",
doi = "10.1007/s12540-020-00837-z"
}

Barjaktarević, D., Međo, B., Štefane, P., Gubeljak, N., Cvijović-Alagić, I., Đokić, V.,& Rakin, M.. (2021). Tensile and Corrosion Properties of Anodized Ultrafne‑Grained
Ti–13Nb–13Zr Biomedical Alloy Obtained by High‑Pressure Torsion. in Metals and Materials International, 27(9), 3325-3341.
https://doi.org/10.1007/s12540-020-00837-z

Barjaktarević D, Međo B, Štefane P, Gubeljak N, Cvijović-Alagić I, Đokić V, Rakin M. Tensile and Corrosion Properties of Anodized Ultrafne‑Grained
Ti–13Nb–13Zr Biomedical Alloy Obtained by High‑Pressure Torsion. in Metals and Materials International. 2021;27(9):3325-3341.
doi:10.1007/s12540-020-00837-z .

Barjaktarević, Dragana, Međo, Bojan, Štefane, Primož, Gubeljak, Nenad, Cvijović-Alagić, Ivana, Đokić, Veljko, Rakin, Marko, "Tensile and Corrosion Properties of Anodized Ultrafne‑Grained
Ti–13Nb–13Zr Biomedical Alloy Obtained by High‑Pressure Torsion" in Metals and Materials International, 27, no. 9 (2021):3325-3341,
https://doi.org/10.1007/s12540-020-00837-z . .

TY  - JOUR
AU  - Barjaktarević, Dragana
AU  - Međo, Bojan
AU  - Gubeljak, Nenad
AU  - Cvijović-Alagić, Ivana
AU  - Štefane, Primož
AU  - Đokić, Veljko
AU  - Rakin, Marko
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9557
AB  - Due to their excellent mechanical properties and corrosion resistance, titanium-based materials are widely represented in aeronautics, chemical industry and medicine, where they are considered the best replacement for damaged hard tissues. In order to obtain optimal properties for medical applications, commercially pure titanium (cpTi) is often alloyed. The ß-type titanium alloys containing Nb, Zr, Ta, Mo, Sn have attracted considerable attention, due to their unique combinations of high strength, low modulus of elasticity, superior corrosion resistance and biocompatibility. Also, titanium-based materials can be processed by surface modifications, including the anodization, which belongs to the group of chemical nanostructured surface modifications. Analysis of microstructure of two-phase Ti-13Nb-13Zr (TNZ) alloy was done by Scanning Electron Microscopy (SEM). Characterisation of surface, obtained by anodization in the H3PO4 + NaF solution, during 90 minutes process, was performed by SEM. Micro Tensile Specimens (MTS) were cut from TNZ and anodized TNZ disks and were subjected to the tensile test using servo-hydraulic testing machine Instron 1255. Stereometric measurement of strain at the surface of the MTS during tension was done using the Aramis system. Results showed that anodization process led to a creation of heterogeneous layer of nanotubes. Anodized TNZ alloy had lower elastic modulus and tensile strength comparing to the initial alloy. In order to better understand tensile behaviour, numerical analysis of non-anodized alloy was done. The 3D numerical model of MTS, which simulated the tensile test, was made in Abaqus software package. Good correlation between experimental and numerical results was obtained. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)
T2  - Procedia Structural Integrity
T1  - Experimental and numerical analysis of tensile properties of Ti-13Nb-13Zr alloy and determination of influence of anodization process
VL  - 28
SP  - 2187
EP  - 2194
DO  - 10.1016/j.prostr.2020.11.047
ER  - 

@article{
author = "Barjaktarević, Dragana and Međo, Bojan and Gubeljak, Nenad and Cvijović-Alagić, Ivana and Štefane, Primož and Đokić, Veljko and Rakin, Marko",
year = "2020",
abstract = "Due to their excellent mechanical properties and corrosion resistance, titanium-based materials are widely represented in aeronautics, chemical industry and medicine, where they are considered the best replacement for damaged hard tissues. In order to obtain optimal properties for medical applications, commercially pure titanium (cpTi) is often alloyed. The ß-type titanium alloys containing Nb, Zr, Ta, Mo, Sn have attracted considerable attention, due to their unique combinations of high strength, low modulus of elasticity, superior corrosion resistance and biocompatibility. Also, titanium-based materials can be processed by surface modifications, including the anodization, which belongs to the group of chemical nanostructured surface modifications. Analysis of microstructure of two-phase Ti-13Nb-13Zr (TNZ) alloy was done by Scanning Electron Microscopy (SEM). Characterisation of surface, obtained by anodization in the H3PO4 + NaF solution, during 90 minutes process, was performed by SEM. Micro Tensile Specimens (MTS) were cut from TNZ and anodized TNZ disks and were subjected to the tensile test using servo-hydraulic testing machine Instron 1255. Stereometric measurement of strain at the surface of the MTS during tension was done using the Aramis system. Results showed that anodization process led to a creation of heterogeneous layer of nanotubes. Anodized TNZ alloy had lower elastic modulus and tensile strength comparing to the initial alloy. In order to better understand tensile behaviour, numerical analysis of non-anodized alloy was done. The 3D numerical model of MTS, which simulated the tensile test, was made in Abaqus software package. Good correlation between experimental and numerical results was obtained. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)",
journal = "Procedia Structural Integrity",
title = "Experimental and numerical analysis of tensile properties of Ti-13Nb-13Zr alloy and determination of influence of anodization process",
volume = "28",
pages = "2187-2194",
doi = "10.1016/j.prostr.2020.11.047"
}

Barjaktarević, D., Međo, B., Gubeljak, N., Cvijović-Alagić, I., Štefane, P., Đokić, V.,& Rakin, M.. (2020). Experimental and numerical analysis of tensile properties of Ti-13Nb-13Zr alloy and determination of influence of anodization process. in Procedia Structural Integrity, 28, 2187-2194.
https://doi.org/10.1016/j.prostr.2020.11.047

Barjaktarević D, Međo B, Gubeljak N, Cvijović-Alagić I, Štefane P, Đokić V, Rakin M. Experimental and numerical analysis of tensile properties of Ti-13Nb-13Zr alloy and determination of influence of anodization process. in Procedia Structural Integrity. 2020;28:2187-2194.
doi:10.1016/j.prostr.2020.11.047 .

Barjaktarević, Dragana, Međo, Bojan, Gubeljak, Nenad, Cvijović-Alagić, Ivana, Štefane, Primož, Đokić, Veljko, Rakin, Marko, "Experimental and numerical analysis of tensile properties of Ti-13Nb-13Zr alloy and determination of influence of anodization process" in Procedia Structural Integrity, 28 (2020):2187-2194,
https://doi.org/10.1016/j.prostr.2020.11.047 . .