TY  - JOUR
AU  - Jovanović, Gvozden
AU  - Glišić, Dragomir
AU  - Dikić, Stefan
AU  - Međo, Bojan
AU  - Marković, Branislav
AU  - Vuković, Nikola
AU  - Radović, Nenad
PY  - 2023
UR  - https://ritnms.itnms.ac.rs/handle/123456789/1174
AB  - Two medium-carbon microalloyed steels with a predominant acicular ferrite microstructure were investigated in this study in order to determine the initial micro-crack formation mechanism and the role of acicular ferrite structure in cleavage fracture. In order to ensure cleavage fracture, samples were investigated at −196 ◦C for uniaxial tension and four point bending fracture. Previous investigations have shown that cleavage fracture for steels with a predominant acicular ferrite microstructure has not been initiated by the fracture of coarse TiN particles as in ferrite-pearlite,
bainite, or martensitic microalloyed steels. The average maximal thickness of cementite plates measured in this work is 0.798 µm and 0.966 µm, for V and TiV steel, respectively. The corresponding stress values required for their fracture according to Griffith’s equation are 1970 MPa and 1791 MPa,
respectively. Estimated values of the effective surface energy for the V steel with an average cementite volume fraction of 3.8% range from 40 Jm−2 to 86 Jm−2, and for the TiV steel with an average cementite volume fraction of 18.3% range from 55 Jm−2 to 82 Jm−2. The fracture of coarse cementite plates was found to not to be responsible for the cleavage fracture initiation in case of both steels.
PB  - MDPI
T2  - Materials
T1  - Determining the role of acicular ferrite carbides in cleavage fracture crack Initiation for two medium carbon microalloyed steels
IS  - 22
VL  - 16
DO  - 10.3390/ma16227192
ER  - 

@article{
author = "Jovanović, Gvozden and Glišić, Dragomir and Dikić, Stefan and Međo, Bojan and Marković, Branislav and Vuković, Nikola and Radović, Nenad",
year = "2023",
abstract = "Two medium-carbon microalloyed steels with a predominant acicular ferrite microstructure were investigated in this study in order to determine the initial micro-crack formation mechanism and the role of acicular ferrite structure in cleavage fracture. In order to ensure cleavage fracture, samples were investigated at −196 ◦C for uniaxial tension and four point bending fracture. Previous investigations have shown that cleavage fracture for steels with a predominant acicular ferrite microstructure has not been initiated by the fracture of coarse TiN particles as in ferrite-pearlite,
bainite, or martensitic microalloyed steels. The average maximal thickness of cementite plates measured in this work is 0.798 µm and 0.966 µm, for V and TiV steel, respectively. The corresponding stress values required for their fracture according to Griffith’s equation are 1970 MPa and 1791 MPa,
respectively. Estimated values of the effective surface energy for the V steel with an average cementite volume fraction of 3.8% range from 40 Jm−2 to 86 Jm−2, and for the TiV steel with an average cementite volume fraction of 18.3% range from 55 Jm−2 to 82 Jm−2. The fracture of coarse cementite plates was found to not to be responsible for the cleavage fracture initiation in case of both steels.",
publisher = "MDPI",
journal = "Materials",
title = "Determining the role of acicular ferrite carbides in cleavage fracture crack Initiation for two medium carbon microalloyed steels",
number = "22",
volume = "16",
doi = "10.3390/ma16227192"
}

Jovanović, G., Glišić, D., Dikić, S., Međo, B., Marković, B., Vuković, N.,& Radović, N.. (2023). Determining the role of acicular ferrite carbides in cleavage fracture crack Initiation for two medium carbon microalloyed steels. in Materials
MDPI., 16(22).
https://doi.org/10.3390/ma16227192

Jovanović G, Glišić D, Dikić S, Međo B, Marković B, Vuković N, Radović N. Determining the role of acicular ferrite carbides in cleavage fracture crack Initiation for two medium carbon microalloyed steels. in Materials. 2023;16(22).
doi:10.3390/ma16227192 .

Jovanović, Gvozden, Glišić, Dragomir, Dikić, Stefan, Međo, Bojan, Marković, Branislav, Vuković, Nikola, Radović, Nenad, "Determining the role of acicular ferrite carbides in cleavage fracture crack Initiation for two medium carbon microalloyed steels" in Materials, 16, no. 22 (2023),
https://doi.org/10.3390/ma16227192 . .

TY  - JOUR
AU  - Dikić, Stefan
AU  - Glišić, Dragomir
AU  - Fadel, Abdunaser
AU  - Jovanović, Gvozden
AU  - Radović, Nenad
PY  - 2022
UR  - https://ritnms.itnms.ac.rs/handle/123456789/625
AB  - The aim of this work was to establish a temperature of finish rolling stage of Nb/Ti microalloyed steel containing 0.06 wt.% C, 0.77 wt.% Mn, 0.039 wt.% Nb and 0.015 wt.% Ti, using physical simulation. Samples were subjected to laboratory simulation at a twist plastometer at high temperatures, i.e. between 825 and 950 degrees C. Five pass deformation and interpass times were selected in accordance with a processing parameters at five stand finishing hot strip mill. Restoration (recovery and/or recrystallization) behavior was evaluated by calculation of Fraction Softening (FS) and Area Softening Parameter (ASP) values. At 950 degrees C all individual pass stress-strain curves, FS and ASP show full recrystallization in all interpass intervals. On the other hand, with a decrease in temperature to the interval of 875-825 degrees C, the extent of restoration is decreasing, leading to recovery as a sole softening mechanism at 825 degrees C, which was confirmed by the stress-strain curve shape, and values of FS and ASP. It is assumed that, due to high supersaturation, strain-induced precipitation promoted pinning of grain and subgrain boundaries and suppressed recrystallization. Therefore, the critical temperature for finish rolling was estimated to be 825 degrees C.
PB  - Savez hemijskih inženjera, Beograd
T2  - Hemijska industrija
T1  - Physical simulation of finish rolling of microalloyed steels in isothermal conditions
EP  - 236
IS  - 4
SP  - 227
VL  - 76
DO  - 10.2298/HEMIND220816018D
UR  - conv_962
ER  - 

@article{
author = "Dikić, Stefan and Glišić, Dragomir and Fadel, Abdunaser and Jovanović, Gvozden and Radović, Nenad",
year = "2022",
abstract = "The aim of this work was to establish a temperature of finish rolling stage of Nb/Ti microalloyed steel containing 0.06 wt.% C, 0.77 wt.% Mn, 0.039 wt.% Nb and 0.015 wt.% Ti, using physical simulation. Samples were subjected to laboratory simulation at a twist plastometer at high temperatures, i.e. between 825 and 950 degrees C. Five pass deformation and interpass times were selected in accordance with a processing parameters at five stand finishing hot strip mill. Restoration (recovery and/or recrystallization) behavior was evaluated by calculation of Fraction Softening (FS) and Area Softening Parameter (ASP) values. At 950 degrees C all individual pass stress-strain curves, FS and ASP show full recrystallization in all interpass intervals. On the other hand, with a decrease in temperature to the interval of 875-825 degrees C, the extent of restoration is decreasing, leading to recovery as a sole softening mechanism at 825 degrees C, which was confirmed by the stress-strain curve shape, and values of FS and ASP. It is assumed that, due to high supersaturation, strain-induced precipitation promoted pinning of grain and subgrain boundaries and suppressed recrystallization. Therefore, the critical temperature for finish rolling was estimated to be 825 degrees C.",
publisher = "Savez hemijskih inženjera, Beograd",
journal = "Hemijska industrija",
title = "Physical simulation of finish rolling of microalloyed steels in isothermal conditions",
pages = "236-227",
number = "4",
volume = "76",
doi = "10.2298/HEMIND220816018D",
url = "conv_962"
}

Dikić, S., Glišić, D., Fadel, A., Jovanović, G.,& Radović, N.. (2022). Physical simulation of finish rolling of microalloyed steels in isothermal conditions. in Hemijska industrija
Savez hemijskih inženjera, Beograd., 76(4), 227-236.
https://doi.org/10.2298/HEMIND220816018D
conv_962

Dikić S, Glišić D, Fadel A, Jovanović G, Radović N. Physical simulation of finish rolling of microalloyed steels in isothermal conditions. in Hemijska industrija. 2022;76(4):227-236.
doi:10.2298/HEMIND220816018D
conv_962 .

Dikić, Stefan, Glišić, Dragomir, Fadel, Abdunaser, Jovanović, Gvozden, Radović, Nenad, "Physical simulation of finish rolling of microalloyed steels in isothermal conditions" in Hemijska industrija, 76, no. 4 (2022):227-236,
https://doi.org/10.2298/HEMIND220816018D .,
conv_962 .

TY  - JOUR
AU  - Jovanović, Gvozden
AU  - Glišić, Dragomir
AU  - Dikić, Stefan
AU  - Radović, Nenad
AU  - Patarić, Aleksandra
PY  - 2022
UR  - https://ritnms.itnms.ac.rs/handle/123456789/634
AB  - Cleavage fracture of the V and Ti-V microalloyed forging steels was investigated by the four-point bending testing of the notched specimens of Griffith-Owen's type at -196 degrees C, in conjunction with the finite element analysis and the fractographic examination by scanning electron microscopy. To assess the mixed microstructure consisting mostly of the acicular ferrite, alongside proeutectoid ferrite grains and pearlite, the samples were held at 1250 degrees C for 30 min and subsequently cooled instill air. Cleavage fracture was initiated in the matrix under the high plastic strains near the notch root of the four-point bending specimens without the participation of the second phase particles in the process. Estimated values of the effective surface energy for the V and the Ti-V microalloyed steel of 37 Jm(-2) and 74 Jm(-2), respectively, and the related increase of local critical fracture stress were attributed to the increased content of the acicular ferrite. It was concluded that the observed increase of the local stress for cleavage crack propagation through the matrix was due to the increased number of the high angle boundaries, but also that the acicular ferrite affects the cleavage fracture mechanism by its characteristic stress-strain response with relatively low yield strength and considerable ductility at -196 degrees C.
PB  - MDPI, Basel
T2  - Materials
T1  - Cleavage Fracture of the Air Cooled Medium Carbon Microalloyed Forging Steels with Heterogeneous Microstructures
IS  - 5
VL  - 15
DO  - 10.3390/ma15051760
UR  - conv_938
ER  - 

@article{
author = "Jovanović, Gvozden and Glišić, Dragomir and Dikić, Stefan and Radović, Nenad and Patarić, Aleksandra",
year = "2022",
abstract = "Cleavage fracture of the V and Ti-V microalloyed forging steels was investigated by the four-point bending testing of the notched specimens of Griffith-Owen's type at -196 degrees C, in conjunction with the finite element analysis and the fractographic examination by scanning electron microscopy. To assess the mixed microstructure consisting mostly of the acicular ferrite, alongside proeutectoid ferrite grains and pearlite, the samples were held at 1250 degrees C for 30 min and subsequently cooled instill air. Cleavage fracture was initiated in the matrix under the high plastic strains near the notch root of the four-point bending specimens without the participation of the second phase particles in the process. Estimated values of the effective surface energy for the V and the Ti-V microalloyed steel of 37 Jm(-2) and 74 Jm(-2), respectively, and the related increase of local critical fracture stress were attributed to the increased content of the acicular ferrite. It was concluded that the observed increase of the local stress for cleavage crack propagation through the matrix was due to the increased number of the high angle boundaries, but also that the acicular ferrite affects the cleavage fracture mechanism by its characteristic stress-strain response with relatively low yield strength and considerable ductility at -196 degrees C.",
publisher = "MDPI, Basel",
journal = "Materials",
title = "Cleavage Fracture of the Air Cooled Medium Carbon Microalloyed Forging Steels with Heterogeneous Microstructures",
number = "5",
volume = "15",
doi = "10.3390/ma15051760",
url = "conv_938"
}

Jovanović, G., Glišić, D., Dikić, S., Radović, N.,& Patarić, A.. (2022). Cleavage Fracture of the Air Cooled Medium Carbon Microalloyed Forging Steels with Heterogeneous Microstructures. in Materials
MDPI, Basel., 15(5).
https://doi.org/10.3390/ma15051760
conv_938

Jovanović G, Glišić D, Dikić S, Radović N, Patarić A. Cleavage Fracture of the Air Cooled Medium Carbon Microalloyed Forging Steels with Heterogeneous Microstructures. in Materials. 2022;15(5).
doi:10.3390/ma15051760
conv_938 .

Jovanović, Gvozden, Glišić, Dragomir, Dikić, Stefan, Radović, Nenad, Patarić, Aleksandra, "Cleavage Fracture of the Air Cooled Medium Carbon Microalloyed Forging Steels with Heterogeneous Microstructures" in Materials, 15, no. 5 (2022),
https://doi.org/10.3390/ma15051760 .,
conv_938 .

TY  - JOUR
AU  - Dikić, Stefan
AU  - Glišić, Dragomir
AU  - Fadel, Abdunaser
AU  - Jovanović, Gvozden
AU  - Radović, Nenad
PY  - 2021
UR  - https://ritnms.itnms.ac.rs/handle/123456789/590
AB  - Isothermal transformation characteristics of a medium carbon Ti-V microalloyed steel were investigated using light microscopy, scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and by uniaxial compressive testing. Samples austenitized on 1100 degrees C were isothermally treated in the range from 350 to 600 degrees C and subsequently water quenched. The final microstructure of the samples held at 350 degrees C consisted of bainitic sheaves and had compressive yield strength, approximately from 1000 MPa, which is attributed to high dislocation density of low bainite. At 400 and 450 degrees C, acicular ferrite became prevalent in the microstructure. It was also formed by a displacive mechanism, but the dislocation density was lower, leading to a decrease of compressive yield strength to approximately 700 MPa. The microstructure after the heat treatment at 500 degrees C consisted of coarse non-polygonal ferrite grains separated by pearlite colonies, principally dislocation free grains, so that the compressive YS reached a minimum value of about 700 MPa. The microstructure of the samples heat-treated at 550 and 600 degrees C consisted of pearlite and both grain boundary and intragranular ferrite, alongside with some martensite. After 600 s, austenite became stable and transformed to martensite after water quenching. Therefore, the presence of martensite increased the compressive YS to approx. 800 MPa.
PB  - MDPI, Basel
T2  - Metals
T1  - Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel
IS  - 7
VL  - 11
DO  - 10.3390/met11071011
UR  - conv_911
ER  - 

@article{
author = "Dikić, Stefan and Glišić, Dragomir and Fadel, Abdunaser and Jovanović, Gvozden and Radović, Nenad",
year = "2021",
abstract = "Isothermal transformation characteristics of a medium carbon Ti-V microalloyed steel were investigated using light microscopy, scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and by uniaxial compressive testing. Samples austenitized on 1100 degrees C were isothermally treated in the range from 350 to 600 degrees C and subsequently water quenched. The final microstructure of the samples held at 350 degrees C consisted of bainitic sheaves and had compressive yield strength, approximately from 1000 MPa, which is attributed to high dislocation density of low bainite. At 400 and 450 degrees C, acicular ferrite became prevalent in the microstructure. It was also formed by a displacive mechanism, but the dislocation density was lower, leading to a decrease of compressive yield strength to approximately 700 MPa. The microstructure after the heat treatment at 500 degrees C consisted of coarse non-polygonal ferrite grains separated by pearlite colonies, principally dislocation free grains, so that the compressive YS reached a minimum value of about 700 MPa. The microstructure of the samples heat-treated at 550 and 600 degrees C consisted of pearlite and both grain boundary and intragranular ferrite, alongside with some martensite. After 600 s, austenite became stable and transformed to martensite after water quenching. Therefore, the presence of martensite increased the compressive YS to approx. 800 MPa.",
publisher = "MDPI, Basel",
journal = "Metals",
title = "Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel",
number = "7",
volume = "11",
doi = "10.3390/met11071011",
url = "conv_911"
}

Dikić, S., Glišić, D., Fadel, A., Jovanović, G.,& Radović, N.. (2021). Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel. in Metals
MDPI, Basel., 11(7).
https://doi.org/10.3390/met11071011
conv_911

Dikić S, Glišić D, Fadel A, Jovanović G, Radović N. Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel. in Metals. 2021;11(7).
doi:10.3390/met11071011
conv_911 .

Dikić, Stefan, Glišić, Dragomir, Fadel, Abdunaser, Jovanović, Gvozden, Radović, Nenad, "Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel" in Metals, 11, no. 7 (2021),
https://doi.org/10.3390/met11071011 .,
conv_911 .