The Experts below are selected from a list of 40359 Experts worldwide ranked by ideXlab platform
J. J. Jonas - One of the best experts on this subject based on the ideXlab platform.
-
Torsion textures produced by dynamic recrystallization in α-iron and two interstitial-free steels
Metallurgical and Materials Transactions A, 1998Co-Authors: J. Baczynski, J. J. JonasAbstract:Two interstitial-free (IF) steels and a high-purity α-iron were deformed in torsion over the temperature range of 600 °C to 840 °C, and the textures produced were measured using conventional X-ray techniques. The conditions were chosen so that dynamic recrystallization (DRX) would take place in the ferrite and static recrystallization would be avoided during cooling after deformation. The DRX textures differ from those observed at room temperature and are dominated by the D1 ( % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9vqpe0x% c9q8qqaqFn0dXdir-xcvk9pIe9q8qqaq-dir-f0-yqaqVe0xe9Fve9% Fve9qapdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGymaiaaig% daieaaceWFYaGbaebaaaa!3B68! $$11\bar 2$$ )[111], D2( % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9vqpe0x% c9q8qqaqFn0dXdir-xcvk9pIe9q8qqaq-dir-f0-yqaqVe0xe9Fve9% Fve9qapdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% aIXaGaaGymaaaaieaacaWFYaaaaa!3B61! $$\overline {11} 2$$ )[111], and E2 ( % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9vqpe0x% c9q8qqaqFn0dXdir-xcvk9pIe9q8qqaq-dir-f0-yqaqVe0xe9Fve9% Fve9qapdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGimaiqaig% dagaqeaiaaigdaaaa!3B66! $$0\bar 11$$ )[111] components. The D2 becomes increasingly important as the strain is increased, which leads to weakening of the D1 and disappearance of the E2 at large strains. Texture simulations were carried out using a DRX model based on sequential deformation, Nucleation, and growth steps. The types of oriented Nucleation and selective growth required to reproduce the experimentally observed textures are discussed. The simulations indicate that the low-Energy Nucleation mechanism plays a dominant role in the formation of bcc DRX textures. The results are also interpreted in terms of the continuous ( in situ ) and discontinuous mechanisms of dynamic recrystallization.
-
Torsion textures produced by dynamic recrystallization in α-iron and two interstitial-free steels
Metallurgical and Materials Transactions A, 1998Co-Authors: J. Baczynski, J. J. JonasAbstract:Two interstitial-free (IF) steels and a high-purity α-iron were deformed in torsion over the temperature range of 600 °C to 840 °C, and the textures produced were measured using conventional X-ray techniques. The conditions were chosen so that dynamic recrystallization (DRX) would take place in the ferrite and static recrystallization would be avoided during cooling after deformation. The DRX textures differ from those observed at room temperature and are dominated by the D1 (\(11\bar 2\))[111], D2(\(\overline {11} 2\))[111], and E2 (\(0\bar 11\))[111] components. The D2 becomes increasingly important as the strain is increased, which leads to weakening of the D1 and disappearance of the E2 at large strains. Texture simulations were carried out using a DRX model based on sequential deformation, Nucleation, and growth steps. The types of oriented Nucleation and selective growth required to reproduce the experimentally observed textures are discussed. The simulations indicate that the low-Energy Nucleation mechanism plays a dominant role in the formation of bcc DRX textures. The results are also interpreted in terms of the continuous (in situ) and discontinuous mechanisms of dynamic recrystallization.
-
Modelling Texture Change during the Static Recrystallization of a Cold Rolled and Annealed Ultra Low Carbon Steel Previously Warm Rolled in the Ferrite Region
ISIJ International, 1997Co-Authors: Leo Kestens, J. J. JonasAbstract:An ultra low carbon steel was finish rolled in the ferrite range, cold rolled and annealed. Quantitative analysis of the deformation and annealing textures indicated that high stored Energy Nucleation was the dominant recrystallization mechanism after a conventional rolling reduction of 75 %. When the rolling reduction was increased to 95 %, texture formation during recrystallization was controlled by both oriented Nucleation and selective growth; this involves the rapid growth of nuclei that display 32° and 38° misorientations with respect to the surrounding matrix. Furthermore, variant selection is of critical importance during selective growth; out of six symmetrically equivalent and four symmetrically equivalent axes, the one chosen is closest to the maximum shear stress pole of the sample. The lower rolling reduction gives rise to a relatively weak and homogeneous //ND fibre texture (max.=6 × random). The higher rolling reduction, on the other hand, leads to a much sharper //ND fibre texture (max.=15 × random) with maxima at orientations that display misorientations of 32° and 38° with respect to the component of maximum intensity of the deformation texture (i.e. {311} ). It is shown that the combined drawability and in-plane isotropy improve with rolling reduction because selective growth controlled recrystallization favours the formation of more suitable textures.
-
Orientation selective recrystallization of nonoriented electrical steels
Metallurgical and Materials Transactions A, 1996Co-Authors: L. Kestens, J. J. Jonas, P. Houtte, Etienne AernoudtAbstract:A nonoriented electrical steel that was commercially hot rolled and then given a 70 pct cold reduction on a laboratory mill was annealed at 680 °C for 6 minutes. The sheet was then submitted to a second rolling reduction of 5.2 pct, followed in turn by a second annealing at 730 °C for various times. The textures were measured after the first and second recrystallization treatments and analyzed using a Nucleation and growth model. In the model, the nucleus orientation distribution function is first calculated by assessing the Nucleation probability for each deformed matrix orientation. The Nucleation texture is then transformed into the recrystallization texture by means of an appropriate growth criterion. The calculations indicate that the annealing texture of the conventionally rolled (70 pct reduction) sheet can be accounted for on the basis of random Nucleation followed by selective growth. The latter is characterized by the following physical features: (a) the low mobility of low angle grain boundaries, (b) the enhanced mobility of {110} plane matching boundaries, and (c) variant selection of the (110) plane that carries the largest amount of slip during deformation. The computer simulations also show that low stored Energy Nucleation is favored in the lightly rolled sheet. These nuclei grow into the matrix by a selection mechanism that involves the increased mobility of 219a and 233a (110) coincident site lattice (CSL) boundaries.
-
Orientation Selection During Static Recrystallization of Cross Rolled Non-Oriented Electrical Steels
Textures and Microstructures, 1996Co-Authors: Leo Kestens, J. J. Jonas, P. Van Houtte, Etienne AernoudtAbstract:Very sharp deformation textures, with single maxima of more than 50x random centred on the rotated cube component ({001} ), were produced by submitting a non-oriented electrical steel sheet to various sequences of cross-rolling. The cold rolled sheets were subsequently annealed at 730oC for 3 min. The resulting recrystallization textures were much weaker than the cold rolling textures, displaying maxima of about 5x random at locations some distance away from the {001} cross rolling component.Due to the very sharp character of the rolling texture, the conventional low and high stored Energy Nucleation mechanisms were effectively prevented from operating. Thus orientation selection could only take place by the selective growth of nuclei external to the dominant rolling component. Quantitative analysis of the experimental ODFs revealed that the rolling and recrystallization components are related by Σ27 (31.6o ) and Σ7c (38.2o ) coincidence site lattice (CSL) orientation relations. Simulations of the annealing texture on the basis of random Nucleation and combined Σ27-Σ7c selective growth produced reasonable agreement between the predictions and the experimental results.
Leo Kestens - One of the best experts on this subject based on the ideXlab platform.
-
ICAA13: 13th International Conference on Aluminum Alloys - Modeling the recrystallization textures in particle containing al alloys after various rolling reductions
ICAA13 Pittsburgh, 2012Co-Authors: Jurij Sidor, Roumen Petrov, Koen Decroos, Leo KestensAbstract:Various degrees of rolling reductions account for diverse recrystallization mechanisms and thus different microstructural and texture features. The development of deformation and recrystallization textures is discussed based on experimental data and results of finite element and crystal plasticity simulations. A recrystallization model is presented that incorporates the microstructural heterogeneities and changes in local stored Energy. The experimental observations and results of crystal plasticity calculations testify that orientation selection during recrystallization is controlled by low stored Energy Nucleation which is incorporated in the recrystallization model. Results of texture simulations show that the evolution of {100} and {011} components is related to a particle stimulated Nucleation mechanism.
-
Modelling Texture Change during the Static Recrystallization of a Cold Rolled and Annealed Ultra Low Carbon Steel Previously Warm Rolled in the Ferrite Region
ISIJ International, 1997Co-Authors: Leo Kestens, J. J. JonasAbstract:An ultra low carbon steel was finish rolled in the ferrite range, cold rolled and annealed. Quantitative analysis of the deformation and annealing textures indicated that high stored Energy Nucleation was the dominant recrystallization mechanism after a conventional rolling reduction of 75 %. When the rolling reduction was increased to 95 %, texture formation during recrystallization was controlled by both oriented Nucleation and selective growth; this involves the rapid growth of nuclei that display 32° and 38° misorientations with respect to the surrounding matrix. Furthermore, variant selection is of critical importance during selective growth; out of six symmetrically equivalent and four symmetrically equivalent axes, the one chosen is closest to the maximum shear stress pole of the sample. The lower rolling reduction gives rise to a relatively weak and homogeneous //ND fibre texture (max.=6 × random). The higher rolling reduction, on the other hand, leads to a much sharper //ND fibre texture (max.=15 × random) with maxima at orientations that display misorientations of 32° and 38° with respect to the component of maximum intensity of the deformation texture (i.e. {311} ). It is shown that the combined drawability and in-plane isotropy improve with rolling reduction because selective growth controlled recrystallization favours the formation of more suitable textures.
-
The role of coincident site lattice boundaries during selective growth in interstitial-free steels
Metallurgical and Materials Transactions A, 1996Co-Authors: Peter Gangli, Leo Kestens, John J. JonasAbstract:The development of textures in interstitial-free (IF) steels as a result of annealing after cold rolling is described with the help of a combined Nucleation and growth model. Nucleation is simulated by assuming that high stored Energy Nucleation occurs preferentially in high Taylor factor regions in the 75 to 85 pct cold reduced materials. Growth of the nuclei then takes place by means of Σ (110) type as well as by Σ 7 (111) type coincident site lattice (CSL) transformations. Of the six symmetrically equivalent (110) transformation axes, only the ones near the maximum shear stress poles are assumed to operate. The effects of the migration of individual Σ 9, Σ 11, Σ 17c, Σ 19a, Σ 33a, and Σ 33c (110) boundaries are analyzed. Their relative mobilities and contributions to the final texture are deduced by matching the simulated and experimental preferred orientations using a /ldleast-squares” method. On the basis of experimental results for two steels, the various boundary types are observed to have the following mobility ratios: Σ 33a: 12, Σ 19a:4, Σ 9:1, Σ 33c:l, and Σ 17c: 2.
-
Orientation Selection During Static Recrystallization of Cross Rolled Non-Oriented Electrical Steels
Textures and Microstructures, 1996Co-Authors: Leo Kestens, J. J. Jonas, P. Van Houtte, Etienne AernoudtAbstract:Very sharp deformation textures, with single maxima of more than 50x random centred on the rotated cube component ({001} ), were produced by submitting a non-oriented electrical steel sheet to various sequences of cross-rolling. The cold rolled sheets were subsequently annealed at 730oC for 3 min. The resulting recrystallization textures were much weaker than the cold rolling textures, displaying maxima of about 5x random at locations some distance away from the {001} cross rolling component.Due to the very sharp character of the rolling texture, the conventional low and high stored Energy Nucleation mechanisms were effectively prevented from operating. Thus orientation selection could only take place by the selective growth of nuclei external to the dominant rolling component. Quantitative analysis of the experimental ODFs revealed that the rolling and recrystallization components are related by Σ27 (31.6o ) and Σ7c (38.2o ) coincidence site lattice (CSL) orientation relations. Simulations of the annealing texture on the basis of random Nucleation and combined Σ27-Σ7c selective growth produced reasonable agreement between the predictions and the experimental results.
Iain Todd - One of the best experts on this subject based on the ideXlab platform.
-
No more tears for metal 3D printing
Nature, 2017Co-Authors: Iain ToddAbstract:3D printing could revolutionize manufacturing processes involving metals, but few industrially useful alloys are compatible with the technique. A method has been developed that might open up the 3D printing of all metals. See Letter p.365 3D printing, or additive manufacturing, of metals uses a direct Energy source, such as a laser or electron beam, to alloy powders, but has succeeded for only a few metals. Often, large columnar grains and cracks are generated during the solidification stage. In this paper, John Martin et al . confront this problem for aerospace-grade aluminium alloys that could not previously be 3D-printed. They decorate the metal powder feedstock with grain-refining nanoparticles that target each alloy. The composition of these nanoparticles was computed by identifying matching crystallographic lattice spacing and density to provide a low-Energy Nucleation barrier. During solidification, these nucleants generated small equiaxed grains which more easily accommodated the stresses generated during solidification, reducing the likelihood of cracks forming. The mechanical properties of the resulting structures were superior to those achieved without the grain refiners and comparable to those of wrought metal.
-
Metallurgy: No more tears for metal 3D printing.
Nature, 2017Co-Authors: Iain ToddAbstract:3D printing could revolutionize manufacturing processes involving metals, but few industrially useful alloys are compatible with the technique. A method has been developed that might open up the 3D printing of all metals. See Letter p.365 3D printing, or additive manufacturing, of metals uses a direct Energy source, such as a laser or electron beam, to alloy powders, but has succeeded for only a few metals. Often, large columnar grains and cracks are generated during the solidification stage. In this paper, John Martin et al. confront this problem for aerospace-grade aluminium alloys that could not previously be 3D-printed. They decorate the metal powder feedstock with grain-refining nanoparticles that target each alloy. The composition of these nanoparticles was computed by identifying matching crystallographic lattice spacing and density to provide a low-Energy Nucleation barrier. During solidification, these nucleants generated small equiaxed grains which more easily accommodated the stresses generated during solidification, reducing the likelihood of cracks forming. The mechanical properties of the resulting structures were superior to those achieved without the grain refiners and comparable to those of wrought metal.
J. Baczynski - One of the best experts on this subject based on the ideXlab platform.
-
Torsion textures produced by dynamic recrystallization in α-iron and two interstitial-free steels
Metallurgical and Materials Transactions A, 1998Co-Authors: J. Baczynski, J. J. JonasAbstract:Two interstitial-free (IF) steels and a high-purity α-iron were deformed in torsion over the temperature range of 600 °C to 840 °C, and the textures produced were measured using conventional X-ray techniques. The conditions were chosen so that dynamic recrystallization (DRX) would take place in the ferrite and static recrystallization would be avoided during cooling after deformation. The DRX textures differ from those observed at room temperature and are dominated by the D1 ( % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9vqpe0x% c9q8qqaqFn0dXdir-xcvk9pIe9q8qqaq-dir-f0-yqaqVe0xe9Fve9% Fve9qapdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGymaiaaig% daieaaceWFYaGbaebaaaa!3B68! $$11\bar 2$$ )[111], D2( % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9vqpe0x% c9q8qqaqFn0dXdir-xcvk9pIe9q8qqaq-dir-f0-yqaqVe0xe9Fve9% Fve9qapdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% aIXaGaaGymaaaaieaacaWFYaaaaa!3B61! $$\overline {11} 2$$ )[111], and E2 ( % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9vqpe0x% c9q8qqaqFn0dXdir-xcvk9pIe9q8qqaq-dir-f0-yqaqVe0xe9Fve9% Fve9qapdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGimaiqaig% dagaqeaiaaigdaaaa!3B66! $$0\bar 11$$ )[111] components. The D2 becomes increasingly important as the strain is increased, which leads to weakening of the D1 and disappearance of the E2 at large strains. Texture simulations were carried out using a DRX model based on sequential deformation, Nucleation, and growth steps. The types of oriented Nucleation and selective growth required to reproduce the experimentally observed textures are discussed. The simulations indicate that the low-Energy Nucleation mechanism plays a dominant role in the formation of bcc DRX textures. The results are also interpreted in terms of the continuous ( in situ ) and discontinuous mechanisms of dynamic recrystallization.
-
Dynamic Recrystallization Textures in Ferrite and Ferritic Stainless Steels
Materials Science Forum, 1998Co-Authors: J. Baczynski, I. Deardo, John J. JonasAbstract:The textures produced in two conventional IF steels, two ferritic stainless steels and α-iron were determined after deformation in torsion over the temperature range 20-1200°C. The experiments were carried out in the ferrite range and the conditions were chosen so as to eliminate the possibility of static recrystallization. The differences between the deformation and dynamic recrystallization (DRX) textures are sharp. The ideal orientations observed at room temperature are F(110) , J1(011) , J2(110) , D1(112) , D2(112) , E1(011) and E2(011) . The texture produced under dynamic recrystallization conditions is dominated by the D1, D2 and E2 components. The simulations indicate that the low stored Energy Nucleation mechanism plays the dominant role in the formation of bcc DRX textures. The results are also interpreted in terms of the continuous (in situ) and discontinuous mechanisms of dynamic recrystallization.
-
Torsion textures produced by dynamic recrystallization in α-iron and two interstitial-free steels
Metallurgical and Materials Transactions A, 1998Co-Authors: J. Baczynski, J. J. JonasAbstract:Two interstitial-free (IF) steels and a high-purity α-iron were deformed in torsion over the temperature range of 600 °C to 840 °C, and the textures produced were measured using conventional X-ray techniques. The conditions were chosen so that dynamic recrystallization (DRX) would take place in the ferrite and static recrystallization would be avoided during cooling after deformation. The DRX textures differ from those observed at room temperature and are dominated by the D1 (\(11\bar 2\))[111], D2(\(\overline {11} 2\))[111], and E2 (\(0\bar 11\))[111] components. The D2 becomes increasingly important as the strain is increased, which leads to weakening of the D1 and disappearance of the E2 at large strains. Texture simulations were carried out using a DRX model based on sequential deformation, Nucleation, and growth steps. The types of oriented Nucleation and selective growth required to reproduce the experimentally observed textures are discussed. The simulations indicate that the low-Energy Nucleation mechanism plays a dominant role in the formation of bcc DRX textures. The results are also interpreted in terms of the continuous (in situ) and discontinuous mechanisms of dynamic recrystallization.
John J. Jonas - One of the best experts on this subject based on the ideXlab platform.
-
Dynamic Recrystallization Textures in Ferrite and Ferritic Stainless Steels
Materials Science Forum, 1998Co-Authors: J. Baczynski, I. Deardo, John J. JonasAbstract:The textures produced in two conventional IF steels, two ferritic stainless steels and α-iron were determined after deformation in torsion over the temperature range 20-1200°C. The experiments were carried out in the ferrite range and the conditions were chosen so as to eliminate the possibility of static recrystallization. The differences between the deformation and dynamic recrystallization (DRX) textures are sharp. The ideal orientations observed at room temperature are F(110) , J1(011) , J2(110) , D1(112) , D2(112) , E1(011) and E2(011) . The texture produced under dynamic recrystallization conditions is dominated by the D1, D2 and E2 components. The simulations indicate that the low stored Energy Nucleation mechanism plays the dominant role in the formation of bcc DRX textures. The results are also interpreted in terms of the continuous (in situ) and discontinuous mechanisms of dynamic recrystallization.
-
The role of coincident site lattice boundaries during selective growth in interstitial-free steels
Metallurgical and Materials Transactions A, 1996Co-Authors: Peter Gangli, Leo Kestens, John J. JonasAbstract:The development of textures in interstitial-free (IF) steels as a result of annealing after cold rolling is described with the help of a combined Nucleation and growth model. Nucleation is simulated by assuming that high stored Energy Nucleation occurs preferentially in high Taylor factor regions in the 75 to 85 pct cold reduced materials. Growth of the nuclei then takes place by means of Σ (110) type as well as by Σ 7 (111) type coincident site lattice (CSL) transformations. Of the six symmetrically equivalent (110) transformation axes, only the ones near the maximum shear stress poles are assumed to operate. The effects of the migration of individual Σ 9, Σ 11, Σ 17c, Σ 19a, Σ 33a, and Σ 33c (110) boundaries are analyzed. Their relative mobilities and contributions to the final texture are deduced by matching the simulated and experimental preferred orientations using a /ldleast-squares” method. On the basis of experimental results for two steels, the various boundary types are observed to have the following mobility ratios: Σ 33a: 12, Σ 19a:4, Σ 9:1, Σ 33c:l, and Σ 17c: 2.