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Akihisa Inoue - One of the best experts on this subject based on the ideXlab platform.
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relation between time temperature Transformation and continuous Heating Transformation diagrams of metallic glassy alloys
Physica B-condensed Matter, 2005Co-Authors: D V Louzguineluzgin, Akihisa InoueAbstract:Abstract The time–temperature Transformation (TTT) diagrams for the onset of devitrification of the Ge–Ni–La and Cu–Hf–Ti glassy alloys were calculated from the isothermal differential calorimetry data using an Arrhenius equation. The continuous Heating Transformation (CHT) diagrams for the onset of devitrification of the glassy alloys were subsequently recalculated from TTT diagrams. The recalculation method used for conversion of the TTT into CHT diagrams produces reasonable results and is not sensitive to the type of the devitrification reaction (polymorphous or primary Transformation). The diagrams allow to perform a comparison of the stabilities of glassy alloys on a long-term scale. The relationship between these diagrams is discussed.
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Relation between time–temperature Transformation and continuous Heating Transformation diagrams of metallic glassy alloys
Physica B-condensed Matter, 2005Co-Authors: Dmitri V. Louzguine-luzgin, Akihisa InoueAbstract:Abstract The time–temperature Transformation (TTT) diagrams for the onset of devitrification of the Ge–Ni–La and Cu–Hf–Ti glassy alloys were calculated from the isothermal differential calorimetry data using an Arrhenius equation. The continuous Heating Transformation (CHT) diagrams for the onset of devitrification of the glassy alloys were subsequently recalculated from TTT diagrams. The recalculation method used for conversion of the TTT into CHT diagrams produces reasonable results and is not sensitive to the type of the devitrification reaction (polymorphous or primary Transformation). The diagrams allow to perform a comparison of the stabilities of glassy alloys on a long-term scale. The relationship between these diagrams is discussed.
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Evaluation of the thermal stability of a Cu60Hf25Ti15 metallic glass
Applied Physics Letters, 2002Co-Authors: Dmitri V Louzguine, Akihisa InoueAbstract:The present letter shows how a continuous Heating Transformation diagram for a Cu60Hf25Ti15 metallic glass can be obtained by applying an extension of the Kissinger analysis. According to the calculation this glass is completely stable in the Earth’s climate for its lifetime. This extension of the Kissinger analysis method can be applied to any other metallic glass.
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Comparison of the long-term thermal stability of various metallic glasses under continuous Heating
Scripta Materialia, 2002Co-Authors: Dmitri V Louzguine, Akihisa InoueAbstract:Abstract Continuous Heating Transformation diagrams for different metallic glasses were constructed using the differential scanning calorimetry data by applying the corollary of the Kissinger analysis method. The diagrams allow to perform comparison of the stabilities of metallic glasses on the long-term scale.
J. Pacyna - One of the best experts on this subject based on the ideXlab platform.
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THE KINETICS OF PHASE TransformationS IN NEW HOT WORK TOOL STEEL
2014Co-Authors: J. PacynaAbstract:The reason for writing this paper was to describe the kinetics of phase Transformation of undercooled austenite in the form of the CCT (Continuous Cooling Transformation) diagram as well as the kinetics phase Transformation during Heating from as-quenched state in the form of the CHT (Continuous Heating Transformation) diagram of the new hot work tool steel. In order to make the CCT diagram of the kinetics of phase Transformation of undercooled austenite the samples were heated to a temperature of 940°C with a rate of 5C/s, hold for 20 minutes and then cooled with various rates (50÷0.02C/s) to a temperature of 20C. Numerically recorded dilatograms were differentiated to provide more precise readings of characteristic temperatures. In order to make the CHT diagram of the kinetics of phase Transformations at continuous Heating from as-quenched state, the previously quenched samples (TA = 940C, tA = 20 min, cooling with the rate of 30°C/s) were heated with the following rates: 0.05; 0.1; 0.5; 1; 5; 10; 15; 35°C/s to a temperature of 700°C, while changes in the samples elongation in dependence of the temperature were recorded. In this case, numerically recorded dilatograms were also differentiated for a more precise reading of characteristic temperatures. The CCT diagram is characterized by the range of diffusive changes shifted strongly to the right, it means to longer times (high hardenability). During continuous Heating from the as-quenched state the obtained results confirmed the following order of phase Transformations: precipitation of carbide, Transformations of retained austenite within of which Transformations range precipitation of cementite take place, independent nucleation of MC carbides followed by the nucleation of M2C carbides. The increase of Heating rate (from 0.05 to 35°C/s) results in the increase of temperatures of the beginnings and the ends of particular Transformations.
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Influence of the Carbon Content on the Kinetics of Phase Transformations During Continuous Heating from As-Quenched State in a Cr-Mn-Mo Model Alloys / Wpływ Zawartości Węgla Na Kinetykę Przemian Fazowych Podczas Nagrzewania Ze Stanu Zahartowanego W S
Archives of Metallurgy and Materials, 2012Co-Authors: R. Dziurka, J. PacynaAbstract:The presented work concerns the research on the kinetics of phase Transformations during continuous Heating from as-quenched state of three Cr-Mn-Mo model alloys with a different carbon content. The kinetics of phase Transformations during continuous Heating of investigated alloys was presented on the CHT (Continuous, Heating, Transformation) diagrams. The CHT diagrams were made on the grounds of dilatograms recorded for quenched samples, heated with various rates. Also the methodology of the dilatometric samples preparation and the method of the characteristic points determination was described. The investigated alloys are the model alloys. Taking into account their chemical compositions the possibility of improving their properties by means of the heat treatment can be expected. The investigations of the carbon influence on microstructures of model alloys with Cr-Mn-Mo were carried out. Broadening the knowledge on the carbon influence on the kinetics of phase Transformations during continuous Heating from as-quenched state, will help in designing new alloys with a better properties.
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Vanadium influence upon changes at tempering steels of small content of other elements
Journal of Materials Processing Technology, 2006Co-Authors: J. Pacyna, R. DąbrowskiAbstract:Abstract The work presents three continuous–Heating–Transformation (CHT) diagrams at continuous tempering (Heating) for alloys of similar carbon concentration, various vanadium concentration and weak, practically same, “background” of other alloy elements. It has been proved that carbide ɛ precipitation in the researched alloys depends on Heating rate for tempering. The temperatures of the beginning and end of independent nucleating MC type carbides precipitation depend not only on the Heating rate for tempering the alloy but also on vanadium concentration.
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The kinetics of phase Transformations during tempering in structural steels with nickel
Journal of Materials Processing Technology, 2005Co-Authors: G. Zając, J. PacynaAbstract:Abstract The kinetics of phase Transformations during continuous Heating (tempering) from quenched state by means of the CHT (continuous Heating Transformation) diagrams was presented. On these diagrams ranges of temperatures of ɛ carbide and cementite precipitation and retained austenite Transformation were marked. The effect of chemical composition and cooling rate on ranges of temperatures these Transformations were determined. For investigation four model alloys of the variable concentration of Ni and constant concentration of carbon and other elements were used.
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the effect of manganese and silicon on the kinetics of phase Transformations during tempering continuous Heating Transformation cht curves
Journal of Materials Processing Technology, 1997Co-Authors: J. Pacyna, A Jȩdrzejewskastrach, M. StrachAbstract:Abstract The effect of Mn and Si on the kinetics of Phase Transformations was determined at continuous Heating from the quenched state. The investigations were executed on the model alloys of the weak “background” of other elements. The results were presented on the CHT curves (Continuous Heating Transformations) in the temperature-time-Transformation system.
Marcin Kubiak - One of the best experts on this subject based on the ideXlab platform.
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Prediction of microstructure composition in steel plate heated using high power Yb:YAG laser radiation
MATEC Web of Conferences, 2019Co-Authors: Marcin KubiakAbstract:Laser beam processing of steel has increasing application in many industries, mainly due to high process speed and good quality of the product as well as a small zone of thermal influence on the material. The concentration of a laser heat energy leads to the generation of high cooling rates in heat affected zone (HAZ). As a result phase Transformations in solid state are present, which leads to the formation of various structures in HAZ with differing mechanical properties. This work concerns numerical modelling and computer simulations of temperature field and phase Transformations during Yb:YAG laser Heating of sheets made of S355 steel. The distribution of Yb:YAG laser power emitted by Trumpf laser head D70 is used in the analysis. The heat source is modelled on the basis of interpolation algorithms using geostatistical kriging method. Coupled heat transfer and fluid flow in the fusion zone are described respectively by transient heat transfer equation with convective term and Navier-Stokes equation. The kinetics of phase Transformations and volumetric fractions of arising phases are obtained on the basis of Johnson-Mehl-Avrami (JMA) and Koistinen-Marburger (KM) models. Continuous Heating Transformation (CHT) diagram is used for Heating process and Continuous Cooling Transformation (CCT) diagram is used for heated steel with the decomposition of final volume fractions of phases transformed form austenite dependant on cooling rates. Examples of computer simulations are presented including temperature field, velocity field of liquid material in the fusion zone and estimated structure composition of elements made of S355 steel, heated by Yb:YAG laser.
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Comprehensive model of thermal phenomena and phase Transformations in laser welding process
Computers & Structures, 2016Co-Authors: Marcin Kubiak, Wiesława PiekarskaAbstract:Prediction of fusion zone and heat affected zone geometry in laser welding process.Estimation of structural composition of the laser welded joint.Considering austenitization temperatures changing with Heating rates.Determining the impact of latent heats on the temperature field.Comparison of predicted characteristic zones of joints with experimental results. This paper concerns computational modelling of thermal phenomena and phase Transformations in solid state in laser welding process. The analysis is performed on the basis of numerical solution into continuum mechanics governing equations as well as classic Johnson-Mehl-Avrami (JMA) and Koistinen-Marburger (KM) kinetics models with continuous Heating Transformation (CHT) and continuous cooling Transformation (CCT) diagrams of S460 steel. The influence of latent heats on temperature distributions is analysed. Obtained results include temperature field, melted material velocity field in the fusion zone and structure composition of welded joint. Calculations are partially verified by experimental data.
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Numerical estimation of phase Transformations in solid state during Yb:YAG laser Heating of steel sheets
2015Co-Authors: Marcin Kubiak, Wiesława Piekarska, T. Domański, Zbigniew Saternus, Sebastian StanoAbstract:This work concerns the numerical modeling of heat transfer and phase Transformations in solid state occurring during the Yb:YAG laser beam Heating process. The temperature field is obtained by the numerical solution into transient heat transfer equation with convective term. The laser beam heat source model is developed using the Kriging interpolation method with experimental measurements of Yb:YAG laser beam profile taken into account. Phase Transformations are calculated on the basis of Johnson - Mehl - Avrami (JMA) and Koistinen - Marburger (KM) kinetics models as well as continuous Heating Transformation (CHT) and continuous cooling Transformation (CCT) diagrams for S355 steel. On the basis of developed numerical algorithms 3D computer simulations are performed in order to predict temperature history and phase Transformations in Yb:YAG laser Heating process.
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Numerical Modelling of Thermal and Structural Strain in Laser Welding Process / Modelowanie Numeryczne Odkształceń Cieplnych I Strukturalnych W Procesie Spawania Techniką Laserową
Archives of Metallurgy and Materials, 2012Co-Authors: Wiesława Piekarska, Marcin Kubiak, Zbigniew SaternusAbstract:This work concerns numerical modelling of thermal and structural strain, resulting in Heating and cooling of laser butt-welded joints. Numerical analysis of strain is carried out in Abaqus FEA. Through the use of additional author’s subroutines, the structural strain caused by phase Transformations during Heating and cooling of welded elements is taken into account in the analysis. V.I. Machnienko models as well as Continuous Heating Transformation (CHT) and Continuous Cooling Transformation (CCT) diagrams for S355 steel are implemented into UEXPAN subroutine in order to determine the kinetics of phase Transformation in the solid state. The model takes into account thermomechanical properties of the base material varying with temperature. The paper presents results of numerical simulation of temperature field, predicted structural composition, thermal and structural strain in laser butt-welded joints.
Wiesława Piekarska - One of the best experts on this subject based on the ideXlab platform.
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Comprehensive model of thermal phenomena and phase Transformations in laser welding process
Computers & Structures, 2016Co-Authors: Marcin Kubiak, Wiesława PiekarskaAbstract:Prediction of fusion zone and heat affected zone geometry in laser welding process.Estimation of structural composition of the laser welded joint.Considering austenitization temperatures changing with Heating rates.Determining the impact of latent heats on the temperature field.Comparison of predicted characteristic zones of joints with experimental results. This paper concerns computational modelling of thermal phenomena and phase Transformations in solid state in laser welding process. The analysis is performed on the basis of numerical solution into continuum mechanics governing equations as well as classic Johnson-Mehl-Avrami (JMA) and Koistinen-Marburger (KM) kinetics models with continuous Heating Transformation (CHT) and continuous cooling Transformation (CCT) diagrams of S460 steel. The influence of latent heats on temperature distributions is analysed. Obtained results include temperature field, melted material velocity field in the fusion zone and structure composition of welded joint. Calculations are partially verified by experimental data.
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Numerical estimation of phase Transformations in solid state during Yb:YAG laser Heating of steel sheets
2015Co-Authors: Marcin Kubiak, Wiesława Piekarska, T. Domański, Zbigniew Saternus, Sebastian StanoAbstract:This work concerns the numerical modeling of heat transfer and phase Transformations in solid state occurring during the Yb:YAG laser beam Heating process. The temperature field is obtained by the numerical solution into transient heat transfer equation with convective term. The laser beam heat source model is developed using the Kriging interpolation method with experimental measurements of Yb:YAG laser beam profile taken into account. Phase Transformations are calculated on the basis of Johnson - Mehl - Avrami (JMA) and Koistinen - Marburger (KM) kinetics models as well as continuous Heating Transformation (CHT) and continuous cooling Transformation (CCT) diagrams for S355 steel. On the basis of developed numerical algorithms 3D computer simulations are performed in order to predict temperature history and phase Transformations in Yb:YAG laser Heating process.
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Numerical Modelling of Thermal and Structural Strain in Laser Welding Process / Modelowanie Numeryczne Odkształceń Cieplnych I Strukturalnych W Procesie Spawania Techniką Laserową
Archives of Metallurgy and Materials, 2012Co-Authors: Wiesława Piekarska, Marcin Kubiak, Zbigniew SaternusAbstract:This work concerns numerical modelling of thermal and structural strain, resulting in Heating and cooling of laser butt-welded joints. Numerical analysis of strain is carried out in Abaqus FEA. Through the use of additional author’s subroutines, the structural strain caused by phase Transformations during Heating and cooling of welded elements is taken into account in the analysis. V.I. Machnienko models as well as Continuous Heating Transformation (CHT) and Continuous Cooling Transformation (CCT) diagrams for S355 steel are implemented into UEXPAN subroutine in order to determine the kinetics of phase Transformation in the solid state. The model takes into account thermomechanical properties of the base material varying with temperature. The paper presents results of numerical simulation of temperature field, predicted structural composition, thermal and structural strain in laser butt-welded joints.
A.m. Wang - One of the best experts on this subject based on the ideXlab platform.
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Influence of casting temperature on the thermal stability of Zr-based metallic glasses
Journal of Alloys and Compounds, 2010Co-Authors: Jianfeng Mao, H.f. Zhang, A.m. WangAbstract:Influences of casting temperature on the thermal stability of Zr-based metallic glasses (MGs) were analyzed based on continuous Heating Transformation (CHT) diagrams built up by Kissinger analysis. The results indicate that increasing the casting temperature can enhance the thermal stability of MGs, which attributed to the dissipation of pre-existing metastable local-ordering clusters in the melt resulted from the elevating casting temperature. (C) 2010 Elsevier B.V. All rights reserved.