LOJEN, Gorazd ;MAYER, Janez ;BONČINA, Tonica ;ZUPANIČ, Franc . Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4. Strojniški vestnik - Journal of Mechanical Engineering, [S.l.], v. 66, n.12, p. 687-696, december 2020. ISSN 0039-2480. Available at: <https://www.sv-jme.eu/sl/article/single-step-heat-treatment-for-the-restoration-of-mechanical-properties-of-cold-strained-mining-support-steel-31mn4/>. Date accessed: 20 apr. 2024. doi:http://dx.doi.org/10.5545/sv-jme.2020.6818.
Lojen, G., Mayer, J., Bončina, T., & Zupanič, F. (2020). Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4. Strojniški vestnik - Journal of Mechanical Engineering, 66(12), 687-696. doi:http://dx.doi.org/10.5545/sv-jme.2020.6818
@article{sv-jmesv-jme.2020.6818,
author = {Gorazd Lojen and Janez Mayer and Tonica Bončina and Franc Zupanič},
title = {Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4},
journal = {Strojniški vestnik - Journal of Mechanical Engineering},
volume = {66},
number = {12},
year = {2020},
keywords = {microstructure, strain hardening, mechanical properties, recrystallization, steel 31Mn4, steel 1.0520, steel mining supports},
abstract = {The steel 31Mn4+QT630 is used frequently for mining support arches. The supports are cold strained, first during service, and again by re-rolling prior to reinstallation, which results in strain hardening and a loss of ductility. Consequently, many of the rerolled arch-segments are not suitable for reinstallation because their mechanical properties are inadequate. The objective of this work was to assess the feasibility of restoration of the required mechanical properties by means of a cost-efficient single step heat treatment. Specimens were cold deformed to different degrees in the range 0 % to 45 % to establish the relation between the degree of cold deformation and the hardness. Differently strain hardened specimens were subjected to subcritical annealing at temperatures 450 °C to 700 °C in the duration 0.5 h to 8 h to determine a suitable time-temperature combinations. Microstructures and mechanical properties were investigated of as-received, cold strained and recrystallized specimens. Tests performed were optical microscopy, scanning electron microscopy, tensile tests, hardness measurements and Charpy impact tests. Elongation at break of the as-received material was below the requirements of the applicable standard, and its microstructure contained significant fractions of pre-eutectoid ferrite and pearlite. Upon cold straining, hardness increased by approximately 2 HV per 1 % of strain. After one-hour recrystallization at 600 °C to 620 °C, the microstructure consisted of a ferritic matrix containing evenly dispersed globular carbide particles. The original ductility was restored, while the elongation, yield strength, and hardness were higher than in the as-received condition. These results confirmed that it is feasible to restore the original mechanical properties of heavily strained profiles with an adequate single-step heat treatment. Furthermore, they indicated that it should be possible to recover the required properties of inhomogeneously strained material with the same set of well optimized heat treatment parameters. Consequently, it should be possible to increase the reuse rate and to decrease the costs for new support arches significantly.},
issn = {0039-2480}, pages = {687-696}, doi = {10.5545/sv-jme.2020.6818},
url = {https://www.sv-jme.eu/sl/article/single-step-heat-treatment-for-the-restoration-of-mechanical-properties-of-cold-strained-mining-support-steel-31mn4/}
}
Lojen, G.,Mayer, J.,Bončina, T.,Zupanič, F. 2020 December 66. Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4. Strojniški vestnik - Journal of Mechanical Engineering. [Online] 66:12
%A Lojen, Gorazd %A Mayer, Janez %A Bončina, Tonica %A Zupanič, Franc %D 2020 %T Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4 %B 2020 %9 microstructure, strain hardening, mechanical properties, recrystallization, steel 31Mn4, steel 1.0520, steel mining supports %! Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4 %K microstructure, strain hardening, mechanical properties, recrystallization, steel 31Mn4, steel 1.0520, steel mining supports %X The steel 31Mn4+QT630 is used frequently for mining support arches. The supports are cold strained, first during service, and again by re-rolling prior to reinstallation, which results in strain hardening and a loss of ductility. Consequently, many of the rerolled arch-segments are not suitable for reinstallation because their mechanical properties are inadequate. The objective of this work was to assess the feasibility of restoration of the required mechanical properties by means of a cost-efficient single step heat treatment. Specimens were cold deformed to different degrees in the range 0 % to 45 % to establish the relation between the degree of cold deformation and the hardness. Differently strain hardened specimens were subjected to subcritical annealing at temperatures 450 °C to 700 °C in the duration 0.5 h to 8 h to determine a suitable time-temperature combinations. Microstructures and mechanical properties were investigated of as-received, cold strained and recrystallized specimens. Tests performed were optical microscopy, scanning electron microscopy, tensile tests, hardness measurements and Charpy impact tests. Elongation at break of the as-received material was below the requirements of the applicable standard, and its microstructure contained significant fractions of pre-eutectoid ferrite and pearlite. Upon cold straining, hardness increased by approximately 2 HV per 1 % of strain. After one-hour recrystallization at 600 °C to 620 °C, the microstructure consisted of a ferritic matrix containing evenly dispersed globular carbide particles. The original ductility was restored, while the elongation, yield strength, and hardness were higher than in the as-received condition. These results confirmed that it is feasible to restore the original mechanical properties of heavily strained profiles with an adequate single-step heat treatment. Furthermore, they indicated that it should be possible to recover the required properties of inhomogeneously strained material with the same set of well optimized heat treatment parameters. Consequently, it should be possible to increase the reuse rate and to decrease the costs for new support arches significantly. %U https://www.sv-jme.eu/sl/article/single-step-heat-treatment-for-the-restoration-of-mechanical-properties-of-cold-strained-mining-support-steel-31mn4/ %0 Journal Article %R 10.5545/sv-jme.2020.6818 %& 687 %P 10 %J Strojniški vestnik - Journal of Mechanical Engineering %V 66 %N 12 %@ 0039-2480 %8 2020-12-23 %7 2020-12-23
Lojen, Gorazd, Janez Mayer, Tonica Bončina, & Franc Zupanič. "Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4." Strojniški vestnik - Journal of Mechanical Engineering [Online], 66.12 (2020): 687-696. Web. 20 Apr. 2024
TY - JOUR AU - Lojen, Gorazd AU - Mayer, Janez AU - Bončina, Tonica AU - Zupanič, Franc PY - 2020 TI - Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4 JF - Strojniški vestnik - Journal of Mechanical Engineering DO - 10.5545/sv-jme.2020.6818 KW - microstructure, strain hardening, mechanical properties, recrystallization, steel 31Mn4, steel 1.0520, steel mining supports N2 - The steel 31Mn4+QT630 is used frequently for mining support arches. The supports are cold strained, first during service, and again by re-rolling prior to reinstallation, which results in strain hardening and a loss of ductility. Consequently, many of the rerolled arch-segments are not suitable for reinstallation because their mechanical properties are inadequate. The objective of this work was to assess the feasibility of restoration of the required mechanical properties by means of a cost-efficient single step heat treatment. Specimens were cold deformed to different degrees in the range 0 % to 45 % to establish the relation between the degree of cold deformation and the hardness. Differently strain hardened specimens were subjected to subcritical annealing at temperatures 450 °C to 700 °C in the duration 0.5 h to 8 h to determine a suitable time-temperature combinations. Microstructures and mechanical properties were investigated of as-received, cold strained and recrystallized specimens. Tests performed were optical microscopy, scanning electron microscopy, tensile tests, hardness measurements and Charpy impact tests. Elongation at break of the as-received material was below the requirements of the applicable standard, and its microstructure contained significant fractions of pre-eutectoid ferrite and pearlite. Upon cold straining, hardness increased by approximately 2 HV per 1 % of strain. After one-hour recrystallization at 600 °C to 620 °C, the microstructure consisted of a ferritic matrix containing evenly dispersed globular carbide particles. The original ductility was restored, while the elongation, yield strength, and hardness were higher than in the as-received condition. These results confirmed that it is feasible to restore the original mechanical properties of heavily strained profiles with an adequate single-step heat treatment. Furthermore, they indicated that it should be possible to recover the required properties of inhomogeneously strained material with the same set of well optimized heat treatment parameters. Consequently, it should be possible to increase the reuse rate and to decrease the costs for new support arches significantly. UR - https://www.sv-jme.eu/sl/article/single-step-heat-treatment-for-the-restoration-of-mechanical-properties-of-cold-strained-mining-support-steel-31mn4/
@article{{sv-jme}{sv-jme.2020.6818},
author = {Lojen, G., Mayer, J., Bončina, T., Zupanič, F.},
title = {Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4},
journal = {Strojniški vestnik - Journal of Mechanical Engineering},
volume = {66},
number = {12},
year = {2020},
doi = {10.5545/sv-jme.2020.6818},
url = {https://www.sv-jme.eu/sl/article/single-step-heat-treatment-for-the-restoration-of-mechanical-properties-of-cold-strained-mining-support-steel-31mn4/}
}
TY - JOUR AU - Lojen, Gorazd AU - Mayer, Janez AU - Bončina, Tonica AU - Zupanič, Franc PY - 2020/12/23 TI - Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4 JF - Strojniški vestnik - Journal of Mechanical Engineering; Vol 66, No 12 (2020): Strojniški vestnik - Journal of Mechanical Engineering DO - 10.5545/sv-jme.2020.6818 KW - microstructure, strain hardening, mechanical properties, recrystallization, steel 31Mn4, steel 1.0520, steel mining supports N2 - The steel 31Mn4+QT630 is used frequently for mining support arches. The supports are cold strained, first during service, and again by re-rolling prior to reinstallation, which results in strain hardening and a loss of ductility. Consequently, many of the rerolled arch-segments are not suitable for reinstallation because their mechanical properties are inadequate. The objective of this work was to assess the feasibility of restoration of the required mechanical properties by means of a cost-efficient single step heat treatment. Specimens were cold deformed to different degrees in the range 0 % to 45 % to establish the relation between the degree of cold deformation and the hardness. Differently strain hardened specimens were subjected to subcritical annealing at temperatures 450 °C to 700 °C in the duration 0.5 h to 8 h to determine a suitable time-temperature combinations. Microstructures and mechanical properties were investigated of as-received, cold strained and recrystallized specimens. Tests performed were optical microscopy, scanning electron microscopy, tensile tests, hardness measurements and Charpy impact tests. Elongation at break of the as-received material was below the requirements of the applicable standard, and its microstructure contained significant fractions of pre-eutectoid ferrite and pearlite. Upon cold straining, hardness increased by approximately 2 HV per 1 % of strain. After one-hour recrystallization at 600 °C to 620 °C, the microstructure consisted of a ferritic matrix containing evenly dispersed globular carbide particles. The original ductility was restored, while the elongation, yield strength, and hardness were higher than in the as-received condition. These results confirmed that it is feasible to restore the original mechanical properties of heavily strained profiles with an adequate single-step heat treatment. Furthermore, they indicated that it should be possible to recover the required properties of inhomogeneously strained material with the same set of well optimized heat treatment parameters. Consequently, it should be possible to increase the reuse rate and to decrease the costs for new support arches significantly. UR - https://www.sv-jme.eu/sl/article/single-step-heat-treatment-for-the-restoration-of-mechanical-properties-of-cold-strained-mining-support-steel-31mn4/
Lojen, Gorazd, Mayer, Janez, Bončina, Tonica, AND Zupanič, Franc. "Single-Step Heat Treatment for the Restoration of Mechanical Properties of Cold-Strained Mining Support Steel 31Mn4" Strojniški vestnik - Journal of Mechanical Engineering [Online], Volume 66 Number 12 (23 December 2020)
Strojniški vestnik - Journal of Mechanical Engineering 66(2020)12, 687-696
© The Authors, CC-BY 4.0 Int. Change in copyright policy from 2022, Jan 1st.
The steel 31Mn4+QT630 is used frequently for mining support arches. The supports are cold strained, first during service, and again by re-rolling prior to reinstallation, which results in strain hardening and a loss of ductility. Consequently, many of the rerolled arch-segments are not suitable for reinstallation because their mechanical properties are inadequate. The objective of this work was to assess the feasibility of restoration of the required mechanical properties by means of a cost-efficient single step heat treatment. Specimens were cold deformed to different degrees in the range 0 % to 45 % to establish the relation between the degree of cold deformation and the hardness. Differently strain hardened specimens were subjected to subcritical annealing at temperatures 450 °C to 700 °C in the duration 0.5 h to 8 h to determine a suitable time-temperature combinations. Microstructures and mechanical properties were investigated of as-received, cold strained and recrystallized specimens. Tests performed were optical microscopy, scanning electron microscopy, tensile tests, hardness measurements and Charpy impact tests. Elongation at break of the as-received material was below the requirements of the applicable standard, and its microstructure contained significant fractions of pre-eutectoid ferrite and pearlite. Upon cold straining, hardness increased by approximately 2 HV per 1 % of strain. After one-hour recrystallization at 600 °C to 620 °C, the microstructure consisted of a ferritic matrix containing evenly dispersed globular carbide particles. The original ductility was restored, while the elongation, yield strength, and hardness were higher than in the as-received condition. These results confirmed that it is feasible to restore the original mechanical properties of heavily strained profiles with an adequate single-step heat treatment. Furthermore, they indicated that it should be possible to recover the required properties of inhomogeneously strained material with the same set of well optimized heat treatment parameters. Consequently, it should be possible to increase the reuse rate and to decrease the costs for new support arches significantly.