Presented paper reports the effect of the processing route on the microstructure and microhardnes... more Presented paper reports the effect of the processing route on the microstructure and microhardness in the cold rolled low-carbon sheets processed by dual rolls equal channel extrusion (DRECE). The DRECE process was repeated up to four passes in two processing routes, called routes A and C. As the number of passes increased, the heterogeneous evolution of microhardness and microstructural heterogeneities between the core and surface regions gradually became intensified in both processing routes. The results showed that the DRECE method is a powerful method for processing the sheets with gradient structure and enhanced utility properties. Therefore, it appears that the proposed method has a great potential to a wide range of industrial applications.
Contemporary materials should possess high mechanical properties, physical and chemical, as well ... more Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The above mentioned requirements and expectations regarding the contemporary materials are met by the non-ferrous metals alloys used nowadays, including namely the aluminium and magnesium alloys. Presented experimental work focused on the study and comparison of microstructure and mechanical properties selected non-ferrous metals after application different methods of forming and heat treatment respectively. Tensile test for mechanical properties determination were used. The study of microstructures has been used methods of light microscopy.
Inżynieria materiałowa w obróbce plastycznej prof. dr hab. inż. Stanislav RUSZ 1) , prof. dr hab.... more Inżynieria materiałowa w obróbce plastycznej prof. dr hab. inż. Stanislav RUSZ 1) , prof. dr hab. inż. Lubomír ČÍŽEK 1) , prof. dr hab. inż. Jan DUTKIEWICZ 2) , inż. Stanislav TYLŠAR 1) , inż. Michal SALAJKA 1) , inż. Vaclav DIVIN 1) , inż. Jan KEDROŇ 1) , dr inż. Marcel KLOS 3)
The aim of this study is to evaluate the influence of the roll bonding (RB) process on the mechan... more The aim of this study is to evaluate the influence of the roll bonding (RB) process on the mechanical properties of Al/Cu bimetallic strip specimens. A specially designed test instrument for the cyclic bending test of strip specimens produced by RB has been proposed. The test consists of repeated pulling of a strip of sheet metal through a system of cylindrical countersamples. Samples cut along and across the sheet rolling direction were tested. The specimens were subjected to preliminary microstructural tests using an optical microscope with Nomarski contrast and scanning electron microscopy. The tests showed a slight influence of the orientation of the samples on changes to the mechanical properties of the bimetallic sheets in the cyclic bending process. For samples oriented along the sheet rolling direction, discontinuities in the transition layer were found. The samples oriented perpendicularly to the rolling direction were free of this defect.
Method DRECE (Dual Rolls Equal Channel Extrusion) belongs to a perspective group of technologies ... more Method DRECE (Dual Rolls Equal Channel Extrusion) belongs to a perspective group of technologies utilizing the process of severe plastic deformations (SPD). Used for forming of metallic materials. On the newly developed forming device, unlike the rolling technology, the material is significantly strengthening after the forming process, while maintaining the initial strip sheet dimensions after the first pass through forming device. We want to achieve a significant increase in mechanical properties in as few passages as possible by the forming device, in particular increasing the yield strength Rp0.2 and the ultimate tensile strength Rm, while maintaining good formability. The above-described forming method was used to extrude of two types low carbon steel HC200AM and S235JR. The forming tool, according to the pre-performed experiments, was chosen with an inclination of 108° in the deformation zone. The mechanical properties obtained after first pass through the forming device from the tensile tests.
Archives of Civil and Mechanical Engineering, 2021
The paper presents results of FEM modelling as well as properties and microstructure of the ultra... more The paper presents results of FEM modelling as well as properties and microstructure of the ultralow-carbon ferritic steel after the unconventional SPD process—DRECE (dual rolls equal channel extrusion). Based on the conducted numerical simulation information about the deformation behaviour of a steel strip during the DRECE process was obtained. The simulation results were experimentally verified. The influence of DRECE process on hardness distribution, fracture behaviour and microstructure evolution of the investigated steel was analysed. The increase of steel strength properties after subsequent deformation passes was confirmed. The microstructural investigations revealed that the processed strips exhibit the dislocation cell microstructure and subgrains with mostly low-angle grain boundaries. The grains after processing had relatively high dislocation density and intense microband formation was observed. It was also proved that this unconventional SPD method fosters high grain re...
Suitable and complete sets of stress-strain curves significantly affected by dynamic recrystalliz... more Suitable and complete sets of stress-strain curves significantly affected by dynamic recrystallization were analyzed for 11 different iron, copper, magnesium, titanium or nickel based alloys. Using the same methodology, apparent hot deformation activation energy Q p and Q ss values were calculated for each alloy based on peak stress and steady-state stress values. Linear dependence between quantities Q p and Q ss was found, while Q p values are on average only about 6% higher. This should not be essential in predicting true stress of a specific material depending on the temperature-compensated strain rate and strain.
The paper is aimed on appraisal of influence of preceding deformation on spring steel CCT diagram... more The paper is aimed on appraisal of influence of preceding deformation on spring steel CCT diagrams, which were created on the basis on dilatometric analyses of cooling curves, using universal plastometer Gleeble 3800, CCT and DCCT diagrams after austenitisation at the temperature of 850 °C, which were further supported by metallographic analyses and hardness measurements HV30. Dilatometric tests were performed at different cooling rates in the range from 0.16 to 12 °C/s. The diagrams prepared in this way were compared with the diagrams computed numerically by the specialised software QTSteel under the same conditions. The comparison of the experimentally obtained diagrams with the numerically computed ones confirms irreplaceability of physical experiments due to big differences between reality and numerically computed diagrams. The influence of preceding deformation on anisothermal disintegration of austenite was manifested at each phase transformation, but in case of pearlitic tran...
Purpose: was to investigate impact of cold reduction size and annealing on mechanical properties ... more Purpose: was to investigate impact of cold reduction size and annealing on mechanical properties of HSLA steel. Design/methodology/approach: Testing of strip steel QStE 420 was based on a combination of cold rolling, recrystallization annealing, mechanical testing and metallographic analyses. Findings: It was confirmed that by a suitable combination of size of previous cold deformation and parameters of the following annealing it is possible to influence considerably a complex of mechanical properties of particular strips. Strength properties were more or less decreasing with the rising annealing temperature, whereas plastic properties were increasing. Research limitations/implications: The experiment should be supplemented by additional modes of soft-and recrystallization annealing. Practical implications: The results may be utilized for optimization of terms of heat treatment in a cold rolling mill, exactly in accordance with specific requirements for a relation between plastic and strength properties of the investigated material. Originality/value: Research possibilities of VSB-TUO in the sphere of cold rolling were introduced for the first time.
In the selective laser melting process (SLM), the region irradiated by the laser beam is melted a... more In the selective laser melting process (SLM), the region irradiated by the laser beam is melted and quickly solidified, forming solidification lines (laser scan tracks) with symmetrical shapes. Because of the unique (rapid) crystallization conditions, the subgrain structures, typically observed inside these solidification lines, could also have variable geometric symmetrical patterns, e.g., cellular, pentagonal, or hexagonal cellular. The existence of such distinctive microstructures in SLM-made alloys has a significant impact on their superior mechanical and corrosion properties. Thus, any modification of this symmetrical microstructure (due to post-processing) can degrade or improve the properties of SLM-fabricated alloys. This study presents the experimental results on the effects of heat treatment and ECAP on microstructure modification and corrosion behavior of SLM-fabricated AlSi10Mg alloy. Light microscopy, scanning electron microscopy (SEM), electron backscattered diffractio...
This article presents a study on the effect of strain rate, specimen orientation, and plastic str... more This article presents a study on the effect of strain rate, specimen orientation, and plastic strain on the value and distribution of the temperature of dog-bone 1 mm-thick specimens during their deformation in uniaxial tensile tests. Full-field image correlation and infrared thermography techniques were used. A titanium-stabilised austenitic 321 stainless steel was used as test materials. The dog-bone specimens used for uniaxial tensile tests were cut along the sheet metal rolling direction and three strain rates were considered: 4 × 10−3 s−1, 8 × 10−3 s−1 and 16 × 10−3 s−1. It was found that increasing the strain rate resulted in the intensification of heat generation. High-quality regression models (Ra > 0.9) developed for the austenitic 321 steel revealed that sample orientation does not play a significant role in the heat generation when the sample is plastically deformed. It was found that at the moment of formation of a necking at the highest strain rate, the maximum sampl...
Knowledge of the relaxation properties of metal materials at high temperatures is necessary for t... more Knowledge of the relaxation properties of metal materials at high temperatures is necessary for the verification of susceptibility of castings to the creation of defects during the production process. Generated tensions in the castings are the cause of creation and development of defects. At the acoustic emission (next denoted the "AE") use, tensile tests at high temperatures may, among other things, be used for analysis of the AE signal sources and set, in more detail, the temperature limit of elastic-plastic deformations existence in the material under examination. The AE is, during tensile tests at high temperatures, based on the scanning of released elastic waves generated by sharp tension changes in the body as a result of the subsequent physical-metallurgical processes such as plastic deformation, tension redistributing, creation of microcracks and their spreading in macroscopic scale. The results of testing above mentioned magnesium alloys will serve for evaluation of possibility those magnesium alloys for application of SPD methods. The aim of the acoustic emission monitoring at tensile tests at higher temperatures is therefore the specification of the critical heat barrier of the elastic-plastic condition of materials and provision of information concerning the dynamics of deformation processes at tension including influences of surface layers for which acoustic emission, as confirmed by measurement results is a very suitable method. Presented work was further focused on determination of structure characteristics including investigation of fracture characteristics with use of light microscopy and SEM analysis.
The DRECE method is a very promising method for forming sheet metal sheet using the severe plasti... more The DRECE method is a very promising method for forming sheet metal sheet using the severe plastic deformations (SPD) principle. The DRECE method is characterized by the continuous extrusion of the sheet metal strip by the forming die, which creates a forming angle of 108 ° in the deformation zone. In the case of materials formed by a given method, there is a substantial increase in the mechanical properties, in particular the yield strength, already after the first pass through the forming device, while maintaining sufficient ductility of the materials. This fact is very important for the subsequent use of the method in industrial practice. In order to study the possibility of applying the DRECE method in industrial practice, this work presents proposals for design solutions for industrial use. The proposed design solution is also supplemented by mathematical simulations of the forming process.
ABSTRACT Microstructure and texture evolution in equal channel angular extrusion (ECAE) of inters... more ABSTRACT Microstructure and texture evolution in equal channel angular extrusion (ECAE) of interstitial-free (IF) steel is investigated for up to 4 passes via routes A, BA, BC and C. Observations by transmission electron microscopy reveal that the efficacy of grain refinement depends on both processing route and pass number. The preferred route is found to be route C after 2 passes but route BC after 4 passes. Quantitative analysis of the experimental textures shows the development of {1 1 0}〈u v w〉θ and {h k l}〈1 1 1〉θ partial fiber textures in all routes, but the orientation distribution along these fibers is more uniform in routes A and C than BA and BC. The experimental textures are well predicted using a visco-plastic self-consistent model based on the simple shear assumption of ECAE deformation. Finite element (FE) analysis and further texture simulations using the FE-predicted deformation history suggest that imperfect strain reversal is a main factor for the prevalence of shear-type textures and elongated lamellar substructure observed after the even-numbered passes of route C.
This research paper shows the influence of a repeated SPD (Severe Plastic Deformation) plastic fo... more This research paper shows the influence of a repeated SPD (Severe Plastic Deformation) plastic forming with the DRECE technique (Dual Rolls Equal Channel Extrusion) on hardening of low carbon IF steel. The influence of number of passes through the device on change of mechanical properties, such as tensile strength TS and yield stress YS, of tested steel was tested. The developed method is based on equal channel extrusion with dual rolls and uses a repeated plastic forming to refinement of structure and improve mechanical properties of metal bands [1-2]. For the tested steel the increase of strength properties after the DRECE process was confirmed after the first pass in relation to the initial material. The biggest strain hardening is observed after the fourth pass.
Transactions of the VŠB - Technical University of Ostrava, Mechanical Series, 2017
Protlačená hořčíková slitina Mg-3%Al-1%Zn (AZ31) byla zpracována procesem ECAP (úhlové protlačová... more Protlačená hořčíková slitina Mg-3%Al-1%Zn (AZ31) byla zpracována procesem ECAP (úhlové protlačování rovnostranným kanálem) realizovaného při teplotě 523 K (250 °C). Při teplotě 523 K bylo dosaženo zjemnění průměrné velikosti zrna 2-3 µm, které bylo dosaženo dynamickou rekrystalizací jemné γ faze Mg17Al12 s průměrnou velikostí 200 nm. Vývoj mikrostruktury během ECAP byl systematicky studován na optickém mikroskopu a využitím transmisní elektronové mikroskopie. Klíčová slova AZ31, EX-ECAP, Optická mikroskopie, Transmisní elektronová mikroskopie.
Transactions of the VŠB - Technical University of Ostrava, Mechanical Series, 2016
One of the trends in development of new metal materials, respectively the increase of their mecha... more One of the trends in development of new metal materials, respectively the increase of their mechanical properties, is the use of cyclical plastic deformation. Evaluation of resulting properties of given materials conducted only at the end of the process does not, however, enable to phase individual steps of the cyclical process in order to optimize technological parameters. A very suitable approach to describe the behaviour of materials during repeated plastic deformation seems to consist in a non-destructive analysis of residual stresses. The paper describes the method of analysis of residual stress based on the Barkhausen noise which is applied in the process of increasing mechanical properties of steel plates using the DRECE (Dual Rolling Equal Channel Extrusion) method [1-2].
Presented paper reports the effect of the processing route on the microstructure and microhardnes... more Presented paper reports the effect of the processing route on the microstructure and microhardness in the cold rolled low-carbon sheets processed by dual rolls equal channel extrusion (DRECE). The DRECE process was repeated up to four passes in two processing routes, called routes A and C. As the number of passes increased, the heterogeneous evolution of microhardness and microstructural heterogeneities between the core and surface regions gradually became intensified in both processing routes. The results showed that the DRECE method is a powerful method for processing the sheets with gradient structure and enhanced utility properties. Therefore, it appears that the proposed method has a great potential to a wide range of industrial applications.
Contemporary materials should possess high mechanical properties, physical and chemical, as well ... more Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The above mentioned requirements and expectations regarding the contemporary materials are met by the non-ferrous metals alloys used nowadays, including namely the aluminium and magnesium alloys. Presented experimental work focused on the study and comparison of microstructure and mechanical properties selected non-ferrous metals after application different methods of forming and heat treatment respectively. Tensile test for mechanical properties determination were used. The study of microstructures has been used methods of light microscopy.
Inżynieria materiałowa w obróbce plastycznej prof. dr hab. inż. Stanislav RUSZ 1) , prof. dr hab.... more Inżynieria materiałowa w obróbce plastycznej prof. dr hab. inż. Stanislav RUSZ 1) , prof. dr hab. inż. Lubomír ČÍŽEK 1) , prof. dr hab. inż. Jan DUTKIEWICZ 2) , inż. Stanislav TYLŠAR 1) , inż. Michal SALAJKA 1) , inż. Vaclav DIVIN 1) , inż. Jan KEDROŇ 1) , dr inż. Marcel KLOS 3)
The aim of this study is to evaluate the influence of the roll bonding (RB) process on the mechan... more The aim of this study is to evaluate the influence of the roll bonding (RB) process on the mechanical properties of Al/Cu bimetallic strip specimens. A specially designed test instrument for the cyclic bending test of strip specimens produced by RB has been proposed. The test consists of repeated pulling of a strip of sheet metal through a system of cylindrical countersamples. Samples cut along and across the sheet rolling direction were tested. The specimens were subjected to preliminary microstructural tests using an optical microscope with Nomarski contrast and scanning electron microscopy. The tests showed a slight influence of the orientation of the samples on changes to the mechanical properties of the bimetallic sheets in the cyclic bending process. For samples oriented along the sheet rolling direction, discontinuities in the transition layer were found. The samples oriented perpendicularly to the rolling direction were free of this defect.
Method DRECE (Dual Rolls Equal Channel Extrusion) belongs to a perspective group of technologies ... more Method DRECE (Dual Rolls Equal Channel Extrusion) belongs to a perspective group of technologies utilizing the process of severe plastic deformations (SPD). Used for forming of metallic materials. On the newly developed forming device, unlike the rolling technology, the material is significantly strengthening after the forming process, while maintaining the initial strip sheet dimensions after the first pass through forming device. We want to achieve a significant increase in mechanical properties in as few passages as possible by the forming device, in particular increasing the yield strength Rp0.2 and the ultimate tensile strength Rm, while maintaining good formability. The above-described forming method was used to extrude of two types low carbon steel HC200AM and S235JR. The forming tool, according to the pre-performed experiments, was chosen with an inclination of 108° in the deformation zone. The mechanical properties obtained after first pass through the forming device from the tensile tests.
Archives of Civil and Mechanical Engineering, 2021
The paper presents results of FEM modelling as well as properties and microstructure of the ultra... more The paper presents results of FEM modelling as well as properties and microstructure of the ultralow-carbon ferritic steel after the unconventional SPD process—DRECE (dual rolls equal channel extrusion). Based on the conducted numerical simulation information about the deformation behaviour of a steel strip during the DRECE process was obtained. The simulation results were experimentally verified. The influence of DRECE process on hardness distribution, fracture behaviour and microstructure evolution of the investigated steel was analysed. The increase of steel strength properties after subsequent deformation passes was confirmed. The microstructural investigations revealed that the processed strips exhibit the dislocation cell microstructure and subgrains with mostly low-angle grain boundaries. The grains after processing had relatively high dislocation density and intense microband formation was observed. It was also proved that this unconventional SPD method fosters high grain re...
Suitable and complete sets of stress-strain curves significantly affected by dynamic recrystalliz... more Suitable and complete sets of stress-strain curves significantly affected by dynamic recrystallization were analyzed for 11 different iron, copper, magnesium, titanium or nickel based alloys. Using the same methodology, apparent hot deformation activation energy Q p and Q ss values were calculated for each alloy based on peak stress and steady-state stress values. Linear dependence between quantities Q p and Q ss was found, while Q p values are on average only about 6% higher. This should not be essential in predicting true stress of a specific material depending on the temperature-compensated strain rate and strain.
The paper is aimed on appraisal of influence of preceding deformation on spring steel CCT diagram... more The paper is aimed on appraisal of influence of preceding deformation on spring steel CCT diagrams, which were created on the basis on dilatometric analyses of cooling curves, using universal plastometer Gleeble 3800, CCT and DCCT diagrams after austenitisation at the temperature of 850 °C, which were further supported by metallographic analyses and hardness measurements HV30. Dilatometric tests were performed at different cooling rates in the range from 0.16 to 12 °C/s. The diagrams prepared in this way were compared with the diagrams computed numerically by the specialised software QTSteel under the same conditions. The comparison of the experimentally obtained diagrams with the numerically computed ones confirms irreplaceability of physical experiments due to big differences between reality and numerically computed diagrams. The influence of preceding deformation on anisothermal disintegration of austenite was manifested at each phase transformation, but in case of pearlitic tran...
Purpose: was to investigate impact of cold reduction size and annealing on mechanical properties ... more Purpose: was to investigate impact of cold reduction size and annealing on mechanical properties of HSLA steel. Design/methodology/approach: Testing of strip steel QStE 420 was based on a combination of cold rolling, recrystallization annealing, mechanical testing and metallographic analyses. Findings: It was confirmed that by a suitable combination of size of previous cold deformation and parameters of the following annealing it is possible to influence considerably a complex of mechanical properties of particular strips. Strength properties were more or less decreasing with the rising annealing temperature, whereas plastic properties were increasing. Research limitations/implications: The experiment should be supplemented by additional modes of soft-and recrystallization annealing. Practical implications: The results may be utilized for optimization of terms of heat treatment in a cold rolling mill, exactly in accordance with specific requirements for a relation between plastic and strength properties of the investigated material. Originality/value: Research possibilities of VSB-TUO in the sphere of cold rolling were introduced for the first time.
In the selective laser melting process (SLM), the region irradiated by the laser beam is melted a... more In the selective laser melting process (SLM), the region irradiated by the laser beam is melted and quickly solidified, forming solidification lines (laser scan tracks) with symmetrical shapes. Because of the unique (rapid) crystallization conditions, the subgrain structures, typically observed inside these solidification lines, could also have variable geometric symmetrical patterns, e.g., cellular, pentagonal, or hexagonal cellular. The existence of such distinctive microstructures in SLM-made alloys has a significant impact on their superior mechanical and corrosion properties. Thus, any modification of this symmetrical microstructure (due to post-processing) can degrade or improve the properties of SLM-fabricated alloys. This study presents the experimental results on the effects of heat treatment and ECAP on microstructure modification and corrosion behavior of SLM-fabricated AlSi10Mg alloy. Light microscopy, scanning electron microscopy (SEM), electron backscattered diffractio...
This article presents a study on the effect of strain rate, specimen orientation, and plastic str... more This article presents a study on the effect of strain rate, specimen orientation, and plastic strain on the value and distribution of the temperature of dog-bone 1 mm-thick specimens during their deformation in uniaxial tensile tests. Full-field image correlation and infrared thermography techniques were used. A titanium-stabilised austenitic 321 stainless steel was used as test materials. The dog-bone specimens used for uniaxial tensile tests were cut along the sheet metal rolling direction and three strain rates were considered: 4 × 10−3 s−1, 8 × 10−3 s−1 and 16 × 10−3 s−1. It was found that increasing the strain rate resulted in the intensification of heat generation. High-quality regression models (Ra > 0.9) developed for the austenitic 321 steel revealed that sample orientation does not play a significant role in the heat generation when the sample is plastically deformed. It was found that at the moment of formation of a necking at the highest strain rate, the maximum sampl...
Knowledge of the relaxation properties of metal materials at high temperatures is necessary for t... more Knowledge of the relaxation properties of metal materials at high temperatures is necessary for the verification of susceptibility of castings to the creation of defects during the production process. Generated tensions in the castings are the cause of creation and development of defects. At the acoustic emission (next denoted the "AE") use, tensile tests at high temperatures may, among other things, be used for analysis of the AE signal sources and set, in more detail, the temperature limit of elastic-plastic deformations existence in the material under examination. The AE is, during tensile tests at high temperatures, based on the scanning of released elastic waves generated by sharp tension changes in the body as a result of the subsequent physical-metallurgical processes such as plastic deformation, tension redistributing, creation of microcracks and their spreading in macroscopic scale. The results of testing above mentioned magnesium alloys will serve for evaluation of possibility those magnesium alloys for application of SPD methods. The aim of the acoustic emission monitoring at tensile tests at higher temperatures is therefore the specification of the critical heat barrier of the elastic-plastic condition of materials and provision of information concerning the dynamics of deformation processes at tension including influences of surface layers for which acoustic emission, as confirmed by measurement results is a very suitable method. Presented work was further focused on determination of structure characteristics including investigation of fracture characteristics with use of light microscopy and SEM analysis.
The DRECE method is a very promising method for forming sheet metal sheet using the severe plasti... more The DRECE method is a very promising method for forming sheet metal sheet using the severe plastic deformations (SPD) principle. The DRECE method is characterized by the continuous extrusion of the sheet metal strip by the forming die, which creates a forming angle of 108 ° in the deformation zone. In the case of materials formed by a given method, there is a substantial increase in the mechanical properties, in particular the yield strength, already after the first pass through the forming device, while maintaining sufficient ductility of the materials. This fact is very important for the subsequent use of the method in industrial practice. In order to study the possibility of applying the DRECE method in industrial practice, this work presents proposals for design solutions for industrial use. The proposed design solution is also supplemented by mathematical simulations of the forming process.
ABSTRACT Microstructure and texture evolution in equal channel angular extrusion (ECAE) of inters... more ABSTRACT Microstructure and texture evolution in equal channel angular extrusion (ECAE) of interstitial-free (IF) steel is investigated for up to 4 passes via routes A, BA, BC and C. Observations by transmission electron microscopy reveal that the efficacy of grain refinement depends on both processing route and pass number. The preferred route is found to be route C after 2 passes but route BC after 4 passes. Quantitative analysis of the experimental textures shows the development of {1 1 0}〈u v w〉θ and {h k l}〈1 1 1〉θ partial fiber textures in all routes, but the orientation distribution along these fibers is more uniform in routes A and C than BA and BC. The experimental textures are well predicted using a visco-plastic self-consistent model based on the simple shear assumption of ECAE deformation. Finite element (FE) analysis and further texture simulations using the FE-predicted deformation history suggest that imperfect strain reversal is a main factor for the prevalence of shear-type textures and elongated lamellar substructure observed after the even-numbered passes of route C.
This research paper shows the influence of a repeated SPD (Severe Plastic Deformation) plastic fo... more This research paper shows the influence of a repeated SPD (Severe Plastic Deformation) plastic forming with the DRECE technique (Dual Rolls Equal Channel Extrusion) on hardening of low carbon IF steel. The influence of number of passes through the device on change of mechanical properties, such as tensile strength TS and yield stress YS, of tested steel was tested. The developed method is based on equal channel extrusion with dual rolls and uses a repeated plastic forming to refinement of structure and improve mechanical properties of metal bands [1-2]. For the tested steel the increase of strength properties after the DRECE process was confirmed after the first pass in relation to the initial material. The biggest strain hardening is observed after the fourth pass.
Transactions of the VŠB - Technical University of Ostrava, Mechanical Series, 2017
Protlačená hořčíková slitina Mg-3%Al-1%Zn (AZ31) byla zpracována procesem ECAP (úhlové protlačová... more Protlačená hořčíková slitina Mg-3%Al-1%Zn (AZ31) byla zpracována procesem ECAP (úhlové protlačování rovnostranným kanálem) realizovaného při teplotě 523 K (250 °C). Při teplotě 523 K bylo dosaženo zjemnění průměrné velikosti zrna 2-3 µm, které bylo dosaženo dynamickou rekrystalizací jemné γ faze Mg17Al12 s průměrnou velikostí 200 nm. Vývoj mikrostruktury během ECAP byl systematicky studován na optickém mikroskopu a využitím transmisní elektronové mikroskopie. Klíčová slova AZ31, EX-ECAP, Optická mikroskopie, Transmisní elektronová mikroskopie.
Transactions of the VŠB - Technical University of Ostrava, Mechanical Series, 2016
One of the trends in development of new metal materials, respectively the increase of their mecha... more One of the trends in development of new metal materials, respectively the increase of their mechanical properties, is the use of cyclical plastic deformation. Evaluation of resulting properties of given materials conducted only at the end of the process does not, however, enable to phase individual steps of the cyclical process in order to optimize technological parameters. A very suitable approach to describe the behaviour of materials during repeated plastic deformation seems to consist in a non-destructive analysis of residual stresses. The paper describes the method of analysis of residual stress based on the Barkhausen noise which is applied in the process of increasing mechanical properties of steel plates using the DRECE (Dual Rolling Equal Channel Extrusion) method [1-2].
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