During the execution of this work, two companies, a steel supplier of the wire rod and an AWS 70S... more During the execution of this work, two companies, a steel supplier of the wire rod and an AWS 70S-6 welding electrode factory, joined forces. The electrodes are made from continuous rolls in basically two stages of drawing: dry, consisting of 9 die applying reductions from 6.00 mm to 2.21 mm, and wet (10 die) from 2.21 mm down to 0.90 mm, without intermediate heat treatment. The motivation was to use the installed capacity of the plant of 1000 ton/month. Prior to this work, productivity was close to 800 ton/month. This low productivity was mainly attributed to the undesired cuts that occur during the wet drawing process that hinder the continuity of the operation. The objective of this work was to reduce cuttings in the wet drawing stage by implementing a dynamic drawing mill, which considered the fact that the wear rates of the dies become larger as the cross-section of the wire decreases. This implementation allowed modifying the die distribution, and thus the distribution of draw...
International Journal of Cast Metals Research, 2003
High chromium-high carbon experimental castings were produced using chilled moulds to study their... more High chromium-high carbon experimental castings were produced using chilled moulds to study their resistance while subjected to erosive conditions. An experimental design in which the ratio of chromium over carbon equivalent, the amount of molybdenum and that of vanadium plus titanium were varied each in two different levels to obtain eight different casting conditions. The average size and volume fraction of the carbides present in the castings were determined by quantitative analysis. Samples cut from the ingots were subjected to wear in a specially designed rig that used directly reduced iron pellets as an erosive agent; the design is such that these particles impinge the samples after being impulsed by commercial purity nitrogen heated up to maintain a temperature of 550 a c. A multi-linear statistical model was developed to relate the wear resistance of the samples. It was found that resistance to wear was related to chemical composition, in such a way that the samples that exhibit higher wear were those with the higher amount of molybdenum. It was also found that the distribution of primary carbide sizes could affect resistance to wear.
An AISI 304 austenitic stainless steel square bar, with a length to thickness ratio 5:1 was heate... more An AISI 304 austenitic stainless steel square bar, with a length to thickness ratio 5:1 was heated at 900°C and spray quenched with water using 4 full oval nozzles. Five thermocouples were placed in the probe to record the cooling time-temperature curves. Three were placed at mid-thickness plane, being one in the geometric centre, and the other thermocouples were placed 1/4 thickness and near surface (1 mm). In addition, another two thermocouples were placed in a 45° plane (diagonal from center to square edge), one at 1/2 diagonal and the other near the surface (1 mm from two surfaces in the diagonal, at mm from the square edge). The thermocouples were placed at mid-length in order to ignore the end-cooling effects and to facilitate the computation with 1D heat transfer. In addition, the square edge cooling effect was analyzed. FEM was used to model the transient temperature distribution during cooling. It was found that the cooling rate at the square edge was a factor of 1.5 greate...
Modelling of hot rolling of steel strip involves metallurgical phenomena such as restoration of d... more Modelling of hot rolling of steel strip involves metallurgical phenomena such as restoration of deformed structures, transformation to ferrite and growth of the oxide layer on top of the steel strip. The effect of composition is taken into account when restoration and phase transformation is considered, whereas it is assumed that the chemical composition of the steel substrate does not affect the oxide crust, being common place to consider the oxide just as a thermal barrier and to assume sticking conditions within the roll-gap. Observations indicate that elements such as silicon and manganese, more susceptible to oxidize than iron, affect the growth kinetics, adhesion and the behaviour during deformation of the oxide layer. This work deals with the way used to model various superficial and metallurgical phenomena, and how this knowledge is used to simulate hot rolling of steel strip. K Ke ey yw wo or rd ds s Rolling steel. Modelling. Restoration. Oxidation. (•) Trabajo recibido el día 7 de Febrero de 2007 y aceptado en su forma final el día 10 de Abril de 2007.
The continuing quest for explanations that resolve real-world problems leads to present a two-dim... more The continuing quest for explanations that resolve real-world problems leads to present a two-dimensional model for work rolls used for hot rolling of steel strip in a continuous mill. This model is developed in a novel form using analytic and numerical methods by considering the roll as a semi-infinite solid. Due to the excessive thermal cycles to which the roll is subjected during the processing, the industry requires that the research predicting its thermal behaviour is robust. Therefore, this current research was developed and the heat flow at a steady-state through the two-dimensional model computed in a way that is valued in the industry, and meets its requirements. This paper contributes to the state of art of the modelling and simulation of industrial processes of the real world, as well as in significant learning through the pedagogic practice, and its assessment. This work presents a novel insight for the development of future researches in the field of materials science.
Production of hot rolled steel strip is carried out at temperatures at which oxidation is prone t... more Production of hot rolled steel strip is carried out at temperatures at which oxidation is prone to occur. The oxide crust is subjected to stresses that are originated while growing or are due to the difference between the thermal expansion coefficients of steel and oxide. It is considered that the oxide crust will be in tension when the temperature at the surface of the steel increases and in compression when it decreases. These stresses may cause cracking, buckling and spalling of the oxide. Oxidation to hematite occurs very rapidly once the crust is detached from the surface of the steel, and, in some cases oxide dust clouds will be formed. A model was developed to predict the magnitude and nature of the stresses within the oxide layer considering the temperature changes that take place while the material is being rolled. The model predicts that the oxide crust will deform when compressed and may cause its spalling and, once this occurs it will be expected to form oxide dust clouds.
Page 1. Communication Determination of the Dendrite Coherency Point during Solidification by Mean... more Page 1. Communication Determination of the Dendrite Coherency Point during Solidification by Means of Thermal Diffusivity Analysis RUBE´ N CHA´ VEZ-ZAMARRIPA, J. ANGE´ LICA RAMOS-SALAS, JOSE´ TALAMANTES ...
Ultrasonic spray pyrolysis was used to deposit gold nanoparticles on a glass substrate using ZrO2... more Ultrasonic spray pyrolysis was used to deposit gold nanoparticles on a glass substrate using ZrO2 as a surrounding medium. The deposition was made using three flow rates of caring gas. The characterization was made by UV–Vis spectroscopy, X-ray diffraction, scanning electronic microscopy and atomic force microscopy. The UV–Vis spectra showed that the surface plasmon resonance peak, indicative of the presence
Microstructural evolution of a heat-resisting cast alloy was studied by light and electron optica... more Microstructural evolution of a heat-resisting cast alloy was studied by light and electron optical methods. Samples from a cast pipe, used in a reformer furnace, were cut and aged for up to 6 weeks at 750°C. The material was prepared for metallographic examination in the standard way, and electrolytically etched with an oxalic acid solution. The samples were examined with a light optical and a scanning electron microscope. Examination with the electron microscope was carried out with secondary and backscattered electron detectors; X-ray analysis was conducted at selected areas of the samples. It was found that the microstructure in the as-cast samples consisted of an austenitic matrix and a network of two types of primary carbides (chromium and niobium), whereas that of the aged materials also exhibit a fine dispersion of small chromium carbide precipitates; decomposition of primary niobium carbides was found to occur as aging progressed.
ABSTRACT A series of compression tests were conducted using a servo-hydraulic, computer driven te... more ABSTRACT A series of compression tests were conducted using a servo-hydraulic, computer driven testing machine to deduce the constitutive equations that describe the behavior of commercial purity aluminum deformed at room temperature over a wide range of strain rates. The experimental samples were tested with and without the use of either mineral oil or polytetrafluoroethylene (PTFE) tape. All the tests were performed at constant strain rates up to an equivalent strain close to 1. The load–displacement curves were converted into stress–strain curves using different coefficients of friction. The constitutive equations deduced assuming that a steady state is achieved at large strains are considered to be good enough for using them to predict the strength of the material on a wide range of strains and strain rates. The friction coefficient found to yield the best results was 0.05 for PTFE tape, 0.10 for mineral oil and 0.20 when no lubricant was used.
The thermal and thermoelastic responses of the work rolls used for hot rolling of steel strip are... more The thermal and thermoelastic responses of the work rolls used for hot rolling of steel strip are described by means of an hybrid, analytic-numerical, model. The model assumes that the work roll is heated-up by conduction from the steel slab, and cools-down by the use of cooling headers and to the surrounding media. Fatigue of the work roll is assumed
Aluminium engine blocks require the use of grey iron liners to resist wear from sealings mounted ... more Aluminium engine blocks require the use of grey iron liners to resist wear from sealings mounted in pistons. Liners can be inserted into the piece after machining or can be cast-into the block. The latter method allows for higher productivity, but has the disadvantage to promote the development of residual stresses in critical areas such as the cylinder bridges. These stresses arise from the differences in the thermal expansion coefficient of iron and aluminium and, if high enough, may promote the failure of the block. This work describes the procedure followed to measure the residual stresses that develop in the cylinder bridges in type A319 aluminium-silicon-copper engine blocks with cast-in grey iron liners. The measurements were obtained by extensometric means. It was found that the stresses can be higher than 150 MPa in tension, depending on the geometry and size of the piece. It is concluded that these types of analyses provide for an early advice when changes take place in design, processing or material.
Analysis of the TRIP-effect has been implemented by means of series of axisymmetric compressive t... more Analysis of the TRIP-effect has been implemented by means of series of axisymmetric compressive tests on a Si-Mn bearing TRIP-assisted steel heat treated to vary the amount of retained austenite from 5.70 to 9.11 %. The cylindrical samples were deformed with true strains of 0.25, 0.5 and 1, and constant strain rate of 0.1 s Ϫ1 at room temperature. Microstructural examination of the samples indicates that most of the deformation is sustained by the weakest phase, ferrite. The stress-strain data was fitted to different constitutive equations to evaluate the point at which the TRIP-effect triggers. The results showed that the amount of retained austenite is reduced with the increase of strain. No complete transformation of austenite was found to occur as a fraction of austenite remains untransformed even at equivalent strains as high as one. The behaviour of samples with different amounts of retained austenite, but of equal carbon content, was found to depend on the volume fraction of this structure. It was found that the TRIP-effect was triggered at lower strains, but higher stresses, as the amount of this phase increased.
Corrosion Engineering, Science and Technology, 2004
... Ciencias, Universidad de Valladolid, 47011 Valladolid, Espan˜a. Marta Diéz-Ercilla, Tanya Ros... more ... Ciencias, Universidad de Valladolid, 47011 Valladolid, Espan˜a. Marta Diéz-Ercilla, Tanya Ros-Yan˜ez, Roumen Petrov and Yvan Houbaert are ... de Ingenierıa Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, AP 149-F, 66451 San Nicolás de los Garza, NL, México. ...
... Brenda Trevino-Cardona, Idalia Gómez-de-la-Fuente, and Rafael Colás ... 9E. Velasco, J.Ta... more ... Brenda Trevino-Cardona, Idalia Gómez-de-la-Fuente, and Rafael Colás ... 9E. Velasco, J.Talamantes, S. Cano, S. Valtierra, JF Mojica, and R. Colás, Casting-Chill Interface Heat Transfer during Solidification of an Aluminum Alloy, Metall. Mater. Trans., 30B, 773 (1999). 10E. ...
A series of trials were conducted on a compact rolling mill to evaluate the properties and charac... more A series of trials were conducted on a compact rolling mill to evaluate the properties and characteristics of carbon steel strip hot rolled to less than 2 mm in thickness from thin cast slabs. Steels of two different compositions were studied, the first one, a low carbon steel, was rolled to a total reduction ranging from 94 to 98 %, final thickness ranging from 1.06 to 2.69 mm, whereas the second one was a Nb bearing microalloyed steel rolled to a total reduction of around 96 %. The rolling trials were complemented by means of computer modelling to get a deeper understanding of the process. It was found that the ferritic grain size of the low carbon strips varied from 7 to 10 mm, with the finer sizes found in the thinner strips, the grain size of the microalloyed steel was found to be 3.6 mm. Analysis of the texture of the hot rolled strips indicated that the ferrite in the low carbon resulted from the transformation of recrystallized austenite, in comparison, low intensity transformation texture from unrecrystallized austenite was found in the Nb bearing steel. The observed texture data correlate with the R-values measured.
The phase transformations of high carbon steel during quenching and equalizing were modelled usin... more The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses.
An overview of the effect of elemental composition on resulting properties of castings will be pr... more An overview of the effect of elemental composition on resulting properties of castings will be provided in this article. Additional topical coverage includes: molten metal processes, solidification, casting processes, die casting, heat treating, computational modeling, and microstructural evolution and control.
... Roumen Petrov * , Leo Kestens * , Rafael Colás ** , and Yvan Houbaert * ... REFERENCES 1) L. ... more ... Roumen Petrov * , Leo Kestens * , Rafael Colás ** , and Yvan Houbaert * ... REFERENCES 1) L. Leduc-Lezama, M. Vazquez-del-Mercado and R. Gonzalez-de-la-Peña: Iron Steel Eng., 23 (4), (1997),27. 2) KW Andrews: J. Iron Steel Inst., 203, (1965), 721. ...
During the execution of this work, two companies, a steel supplier of the wire rod and an AWS 70S... more During the execution of this work, two companies, a steel supplier of the wire rod and an AWS 70S-6 welding electrode factory, joined forces. The electrodes are made from continuous rolls in basically two stages of drawing: dry, consisting of 9 die applying reductions from 6.00 mm to 2.21 mm, and wet (10 die) from 2.21 mm down to 0.90 mm, without intermediate heat treatment. The motivation was to use the installed capacity of the plant of 1000 ton/month. Prior to this work, productivity was close to 800 ton/month. This low productivity was mainly attributed to the undesired cuts that occur during the wet drawing process that hinder the continuity of the operation. The objective of this work was to reduce cuttings in the wet drawing stage by implementing a dynamic drawing mill, which considered the fact that the wear rates of the dies become larger as the cross-section of the wire decreases. This implementation allowed modifying the die distribution, and thus the distribution of draw...
International Journal of Cast Metals Research, 2003
High chromium-high carbon experimental castings were produced using chilled moulds to study their... more High chromium-high carbon experimental castings were produced using chilled moulds to study their resistance while subjected to erosive conditions. An experimental design in which the ratio of chromium over carbon equivalent, the amount of molybdenum and that of vanadium plus titanium were varied each in two different levels to obtain eight different casting conditions. The average size and volume fraction of the carbides present in the castings were determined by quantitative analysis. Samples cut from the ingots were subjected to wear in a specially designed rig that used directly reduced iron pellets as an erosive agent; the design is such that these particles impinge the samples after being impulsed by commercial purity nitrogen heated up to maintain a temperature of 550 a c. A multi-linear statistical model was developed to relate the wear resistance of the samples. It was found that resistance to wear was related to chemical composition, in such a way that the samples that exhibit higher wear were those with the higher amount of molybdenum. It was also found that the distribution of primary carbide sizes could affect resistance to wear.
An AISI 304 austenitic stainless steel square bar, with a length to thickness ratio 5:1 was heate... more An AISI 304 austenitic stainless steel square bar, with a length to thickness ratio 5:1 was heated at 900°C and spray quenched with water using 4 full oval nozzles. Five thermocouples were placed in the probe to record the cooling time-temperature curves. Three were placed at mid-thickness plane, being one in the geometric centre, and the other thermocouples were placed 1/4 thickness and near surface (1 mm). In addition, another two thermocouples were placed in a 45° plane (diagonal from center to square edge), one at 1/2 diagonal and the other near the surface (1 mm from two surfaces in the diagonal, at mm from the square edge). The thermocouples were placed at mid-length in order to ignore the end-cooling effects and to facilitate the computation with 1D heat transfer. In addition, the square edge cooling effect was analyzed. FEM was used to model the transient temperature distribution during cooling. It was found that the cooling rate at the square edge was a factor of 1.5 greate...
Modelling of hot rolling of steel strip involves metallurgical phenomena such as restoration of d... more Modelling of hot rolling of steel strip involves metallurgical phenomena such as restoration of deformed structures, transformation to ferrite and growth of the oxide layer on top of the steel strip. The effect of composition is taken into account when restoration and phase transformation is considered, whereas it is assumed that the chemical composition of the steel substrate does not affect the oxide crust, being common place to consider the oxide just as a thermal barrier and to assume sticking conditions within the roll-gap. Observations indicate that elements such as silicon and manganese, more susceptible to oxidize than iron, affect the growth kinetics, adhesion and the behaviour during deformation of the oxide layer. This work deals with the way used to model various superficial and metallurgical phenomena, and how this knowledge is used to simulate hot rolling of steel strip. K Ke ey yw wo or rd ds s Rolling steel. Modelling. Restoration. Oxidation. (•) Trabajo recibido el día 7 de Febrero de 2007 y aceptado en su forma final el día 10 de Abril de 2007.
The continuing quest for explanations that resolve real-world problems leads to present a two-dim... more The continuing quest for explanations that resolve real-world problems leads to present a two-dimensional model for work rolls used for hot rolling of steel strip in a continuous mill. This model is developed in a novel form using analytic and numerical methods by considering the roll as a semi-infinite solid. Due to the excessive thermal cycles to which the roll is subjected during the processing, the industry requires that the research predicting its thermal behaviour is robust. Therefore, this current research was developed and the heat flow at a steady-state through the two-dimensional model computed in a way that is valued in the industry, and meets its requirements. This paper contributes to the state of art of the modelling and simulation of industrial processes of the real world, as well as in significant learning through the pedagogic practice, and its assessment. This work presents a novel insight for the development of future researches in the field of materials science.
Production of hot rolled steel strip is carried out at temperatures at which oxidation is prone t... more Production of hot rolled steel strip is carried out at temperatures at which oxidation is prone to occur. The oxide crust is subjected to stresses that are originated while growing or are due to the difference between the thermal expansion coefficients of steel and oxide. It is considered that the oxide crust will be in tension when the temperature at the surface of the steel increases and in compression when it decreases. These stresses may cause cracking, buckling and spalling of the oxide. Oxidation to hematite occurs very rapidly once the crust is detached from the surface of the steel, and, in some cases oxide dust clouds will be formed. A model was developed to predict the magnitude and nature of the stresses within the oxide layer considering the temperature changes that take place while the material is being rolled. The model predicts that the oxide crust will deform when compressed and may cause its spalling and, once this occurs it will be expected to form oxide dust clouds.
Page 1. Communication Determination of the Dendrite Coherency Point during Solidification by Mean... more Page 1. Communication Determination of the Dendrite Coherency Point during Solidification by Means of Thermal Diffusivity Analysis RUBE´ N CHA´ VEZ-ZAMARRIPA, J. ANGE´ LICA RAMOS-SALAS, JOSE´ TALAMANTES ...
Ultrasonic spray pyrolysis was used to deposit gold nanoparticles on a glass substrate using ZrO2... more Ultrasonic spray pyrolysis was used to deposit gold nanoparticles on a glass substrate using ZrO2 as a surrounding medium. The deposition was made using three flow rates of caring gas. The characterization was made by UV–Vis spectroscopy, X-ray diffraction, scanning electronic microscopy and atomic force microscopy. The UV–Vis spectra showed that the surface plasmon resonance peak, indicative of the presence
Microstructural evolution of a heat-resisting cast alloy was studied by light and electron optica... more Microstructural evolution of a heat-resisting cast alloy was studied by light and electron optical methods. Samples from a cast pipe, used in a reformer furnace, were cut and aged for up to 6 weeks at 750°C. The material was prepared for metallographic examination in the standard way, and electrolytically etched with an oxalic acid solution. The samples were examined with a light optical and a scanning electron microscope. Examination with the electron microscope was carried out with secondary and backscattered electron detectors; X-ray analysis was conducted at selected areas of the samples. It was found that the microstructure in the as-cast samples consisted of an austenitic matrix and a network of two types of primary carbides (chromium and niobium), whereas that of the aged materials also exhibit a fine dispersion of small chromium carbide precipitates; decomposition of primary niobium carbides was found to occur as aging progressed.
ABSTRACT A series of compression tests were conducted using a servo-hydraulic, computer driven te... more ABSTRACT A series of compression tests were conducted using a servo-hydraulic, computer driven testing machine to deduce the constitutive equations that describe the behavior of commercial purity aluminum deformed at room temperature over a wide range of strain rates. The experimental samples were tested with and without the use of either mineral oil or polytetrafluoroethylene (PTFE) tape. All the tests were performed at constant strain rates up to an equivalent strain close to 1. The load–displacement curves were converted into stress–strain curves using different coefficients of friction. The constitutive equations deduced assuming that a steady state is achieved at large strains are considered to be good enough for using them to predict the strength of the material on a wide range of strains and strain rates. The friction coefficient found to yield the best results was 0.05 for PTFE tape, 0.10 for mineral oil and 0.20 when no lubricant was used.
The thermal and thermoelastic responses of the work rolls used for hot rolling of steel strip are... more The thermal and thermoelastic responses of the work rolls used for hot rolling of steel strip are described by means of an hybrid, analytic-numerical, model. The model assumes that the work roll is heated-up by conduction from the steel slab, and cools-down by the use of cooling headers and to the surrounding media. Fatigue of the work roll is assumed
Aluminium engine blocks require the use of grey iron liners to resist wear from sealings mounted ... more Aluminium engine blocks require the use of grey iron liners to resist wear from sealings mounted in pistons. Liners can be inserted into the piece after machining or can be cast-into the block. The latter method allows for higher productivity, but has the disadvantage to promote the development of residual stresses in critical areas such as the cylinder bridges. These stresses arise from the differences in the thermal expansion coefficient of iron and aluminium and, if high enough, may promote the failure of the block. This work describes the procedure followed to measure the residual stresses that develop in the cylinder bridges in type A319 aluminium-silicon-copper engine blocks with cast-in grey iron liners. The measurements were obtained by extensometric means. It was found that the stresses can be higher than 150 MPa in tension, depending on the geometry and size of the piece. It is concluded that these types of analyses provide for an early advice when changes take place in design, processing or material.
Analysis of the TRIP-effect has been implemented by means of series of axisymmetric compressive t... more Analysis of the TRIP-effect has been implemented by means of series of axisymmetric compressive tests on a Si-Mn bearing TRIP-assisted steel heat treated to vary the amount of retained austenite from 5.70 to 9.11 %. The cylindrical samples were deformed with true strains of 0.25, 0.5 and 1, and constant strain rate of 0.1 s Ϫ1 at room temperature. Microstructural examination of the samples indicates that most of the deformation is sustained by the weakest phase, ferrite. The stress-strain data was fitted to different constitutive equations to evaluate the point at which the TRIP-effect triggers. The results showed that the amount of retained austenite is reduced with the increase of strain. No complete transformation of austenite was found to occur as a fraction of austenite remains untransformed even at equivalent strains as high as one. The behaviour of samples with different amounts of retained austenite, but of equal carbon content, was found to depend on the volume fraction of this structure. It was found that the TRIP-effect was triggered at lower strains, but higher stresses, as the amount of this phase increased.
Corrosion Engineering, Science and Technology, 2004
... Ciencias, Universidad de Valladolid, 47011 Valladolid, Espan˜a. Marta Diéz-Ercilla, Tanya Ros... more ... Ciencias, Universidad de Valladolid, 47011 Valladolid, Espan˜a. Marta Diéz-Ercilla, Tanya Ros-Yan˜ez, Roumen Petrov and Yvan Houbaert are ... de Ingenierıa Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, AP 149-F, 66451 San Nicolás de los Garza, NL, México. ...
... Brenda Trevino-Cardona, Idalia Gómez-de-la-Fuente, and Rafael Colás ... 9E. Velasco, J.Ta... more ... Brenda Trevino-Cardona, Idalia Gómez-de-la-Fuente, and Rafael Colás ... 9E. Velasco, J.Talamantes, S. Cano, S. Valtierra, JF Mojica, and R. Colás, Casting-Chill Interface Heat Transfer during Solidification of an Aluminum Alloy, Metall. Mater. Trans., 30B, 773 (1999). 10E. ...
A series of trials were conducted on a compact rolling mill to evaluate the properties and charac... more A series of trials were conducted on a compact rolling mill to evaluate the properties and characteristics of carbon steel strip hot rolled to less than 2 mm in thickness from thin cast slabs. Steels of two different compositions were studied, the first one, a low carbon steel, was rolled to a total reduction ranging from 94 to 98 %, final thickness ranging from 1.06 to 2.69 mm, whereas the second one was a Nb bearing microalloyed steel rolled to a total reduction of around 96 %. The rolling trials were complemented by means of computer modelling to get a deeper understanding of the process. It was found that the ferritic grain size of the low carbon strips varied from 7 to 10 mm, with the finer sizes found in the thinner strips, the grain size of the microalloyed steel was found to be 3.6 mm. Analysis of the texture of the hot rolled strips indicated that the ferrite in the low carbon resulted from the transformation of recrystallized austenite, in comparison, low intensity transformation texture from unrecrystallized austenite was found in the Nb bearing steel. The observed texture data correlate with the R-values measured.
The phase transformations of high carbon steel during quenching and equalizing were modelled usin... more The phase transformations of high carbon steel during quenching and equalizing were modelled using commercial computer packages based on the finite element method and the kinetic transformation of steel. The model was used to predict the temperature and microstructural changes taking place within balls of two different sizes that are used for grinding mineral ores. A good correlation between the temperatures measured by inserted thermocouples and those predicted by the model was obtained after modifying the thermal conductivity of the steel within the temperature domain at which mixed phases are present. The phase transformations predicted were confirmed by metallographic analyses.
An overview of the effect of elemental composition on resulting properties of castings will be pr... more An overview of the effect of elemental composition on resulting properties of castings will be provided in this article. Additional topical coverage includes: molten metal processes, solidification, casting processes, die casting, heat treating, computational modeling, and microstructural evolution and control.
... Roumen Petrov * , Leo Kestens * , Rafael Colás ** , and Yvan Houbaert * ... REFERENCES 1) L. ... more ... Roumen Petrov * , Leo Kestens * , Rafael Colás ** , and Yvan Houbaert * ... REFERENCES 1) L. Leduc-Lezama, M. Vazquez-del-Mercado and R. Gonzalez-de-la-Peña: Iron Steel Eng., 23 (4), (1997),27. 2) KW Andrews: J. Iron Steel Inst., 203, (1965), 721. ...
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