Influence of Thermal Processing in High Magnetic Field on Soft Magnetic Properties and Crystallographic Texture of Non-Oriented Fe-Si Steels

In this work, we report on the effects of high static magnetic field on the formation of desirable crystallographic orientation of grains ("rotating" cube) during the primary recrystallization of non-oriented steels. Vacuum degassed non-oriented steel with the silicon content about 1 wt% was taken from industrial line after final cold rolling with 80% of deformation and then it was subjected to the laboratory annealing at temperature of primary recrystallization. Whole annealing process was carried with and without the applied external magnetic field of 14 T. The analysis of crystallographic orientation of experimental material was studied by electron backscattered diffraction technique. The microstructural and textural observations have shown a small difference in average grain size between samples annealed with and without magnetic field as well as increase of the "rotating" Cube component and decrease of the intensity of deformation texture by application of magnetic field. The magnetic measurements show that the coercivity value of the sample annealed in the magnetic field of 14 T can be reduced by approximately 3% in comparison with sample annealed under the zero field conditions

Microstructure and Texture Evolution in Temper Rolled Fe-Si Steels with New System Nano-Inhibitors Under the Dynamic Annealing Conditions

This work investigates the microstructure and texture evolution in grain-oriented electrotechnical steel with a new inhibition system based on vanadium carbides nano-particles. The novel approach for the preparation of this steel with appropriate final magnetic properties combines not only nanoinhibitors based on the vanadium carbides precipitations but also includes straininduced grain growth mechanism in combination with dynamic continuous annealing during the secondary recrystallization. The experimental grain-oriented steel with proposed new chemical composition was prepared in laboratory conditions. The texture analysis has shown that suggested procedure led the formation of sufficiently strong {110} Goss texture during the short time period of a final annealing process, which is comparable to that obtained in the conventionally treated grain-oriented steels

Improved Processing Technique for Preparation of Non-Oriented Electrical Steels with Low Coercivity

In order to improve soft magnetic properties of vacuum degassed NO steels, an adjusted temper rolling process for development of particular textures {100} was used. The main idea here relies on a deformation-induced grain growth, which promotes preferable formation of the grains with desired orientation. Two vacuum degassed NO steels were chosen as an experimental material. In both cases, a coarse or columnar grained microstructure, with pronounced intensity of cube and Goss texture components, was achieved during a continuous final annealing. The obtained microstructure leads to a significant decrease of coercivity, measured in DC magnetic field. The coercivity of steel with silicon content 2.4 wt.% decreased from 42 A/m to 17 A/m. Even more remarkable improvement of the soft magnetic properties was observed for the steel with Si 0.6 wt.%, where the coercivity value dropped from 68 A/m to 12.7 A/m

Microstructure and Texture Evolution in Temper Rolled Fe-Si Steels with New System Nano-Inhibitors under the Dynamic Annealing Conditions

This work investigates the microstructure and texture evolution in grain-oriented electrotechnical steel with a new inhibition system based on vanadium carbides nano-particles. The novel approach for the preparation of this steel with appropriate final magnetic properties combines not only nanoinhibitors based on the vanadium carbides precipitations but also includes straininduced grain growth mechanism in combination with dynamic continuous annealing during the secondary recrystallization. The experimental grain-oriented steel with proposed new chemical composition was prepared in laboratory conditions. The texture analysis has shown that suggested procedure led the formation of sufficiently strong {110} Goss texture during the short time period of a final annealing process, which is comparable to that obtained in the conventionally treated grain-oriented steels

Effect of Laser Scribing on Soft Magnetic Properties of Conventional Grain-Oriented Silicon Steel

The present work investigates the influence of laser scribing of grain-oriented silicon steel on the improvement of its soft magnetic properties via magnetic domains modification. The experimental material was represented by conventional Fe-3%Si grain-oriented electrical steel that was taken directly from industrial line after the final box annealing. The laser scribing treatments were applied onto the material surface in order to induce thermal stresses having crucial influence on the magnetic domains refinement. The laser scribing conditions have been optimized by introducing thermal stresses onto the experimental material surface leading to optimal refinement of final domains structures and desired magnetic softness minimization. A semiquantitative relationship has been found between the domain patterns and the used fiber laser treating method. The obtained modified domain structure led to a significant decrease in coercivity measured in DC magnetic field from 20 A/m to 12 A/m

Effect of VC inhibitors in combination with unconventional dynamical heat treatment on the magnetic properties of GO steels

The present work investigates some new approaches of grain – oriented steels processes. The suggested approach combines an application of nano – particles VC in combination with dynamic continuous annealing for secondary recrystallization in the investigated steels. Such a dynamical (fast heating) annealing and VC particles was applied to the grain – oriented steels in order to obtain abnormal grain growth with Gass crystallographic orientation development during secondary recrystallization. This abnormal gain growth led to evolution of suficienty sharp {110} Goss texture which is equal to that obtained in conventionally treated GO steels. Moreover, the steels treated by the newly method showed similar magnetic properties as the materials passed the long – time heat treated. The coercive field value of our steels reached ~ 11 A/m. This means that the proposed heat treatment in combination with VC nano – particles lead to development equal material’s quality at significantly shortened time of heat treatment in comparison to the conventional process of GO steel production

Magnetic Losses Evolution of Ferritic Fe-Si Steel Subjected to Temper Rolling at Elevated Temperature

The effects of heat transport phenomena and deformation gradient through the sheet cross-section on the microstructure, texture and magnetic properties of non-oriented Fe-Si steel were investigated. In order to achieve desired conditions for the steel microstructural and textural parameters improvement, a temper rolling process at elevated temperature was examined in combination with subsequent short term annealing, employing fast heating rate in laboratory conditions. The experimental material was represented by conventional medium silicon, vacuum degassed non-oriented steel that was taken directly from industrial line after final annealing. Performed electron back scattered diffraction measurements revealed that the experimental steel, treated by our proposed thermomechanical treatment, was characterized by coarse-grained microstructure with enhanced intensity of rotating cube texture. The magnetic losses of experimental samples were measured in ac magnetic field with 50 Hz frequency on the toroid with external and internal diameters of 25 mm and 15 mm, respectively. These measurements with magnetic field intensity of 2500 A/m showed that the application of our suggested treatment led to clear power losses reduction of the investigated material from initial 9.9 W/kg to 6.4 W/kg, i.e. by more than 35%

Influence of Microstructure Evolution on the Coercive Forces in Low Silicon Non-Oriented Steels

The magnetic properties and their dependence on the peculiarity of microstructure in low silicon non-oriented electrotechnical steels were studied in the present work. The estimation of dc magnetic properties of electrical steels was carried out by measurements of coercive forces. It was shown that the coercive force change in silicon steels is dependent on change of average grain size, crystallographic texture and homogeneity of microstructure of the materials. It was revealed that the steels possessing columnar or huge grained microstructure had the lowest measured values of coercive forces. The materials with such microstructure are characterized by a domination of (100) 〈0vw〉 crystallographic orientation

Структура околошовной зоны закалённой высокоуглеродистой стали после сварки с ускоренным охлаждением

Purpose. Study the structure of the heat-affected zone of a welded joint of high-carbon low-alloy steel hardened to martensite after manual arc welding with accelerated cooling.Research methods. Optical and scanning electron microscopy was used to study microstructures. The hardness of the samples was measured using Vickers hardness tester equipped with a computer-controlled positioning and indentation of the sample, as well as determining the diagonals of the prints.Results. Plates of martensite-hardened high-carbon low-alloyed steel and low-carbon steel immersed in water (except edges to be welded) are welded by manual arc welding. The microstructure of the welded joint was investigat­ed. The sizes of characteristic areas of heat-affected zones and the hardness of the material at various distances from the fusion boundary were determined.Scientific novelty. For the first time, high-carbon steel quenched to martensite without tempering was welded with simultaneous accelerated cooling in water. It has been established that in the structure of the heat-affected zone a solid martensitic layer is not adjacent to the fusion boundary, but is separated from it by a layer of austenite.Practical value. The principal possibility of welding heat-treated high-carbon wear-resistant steels without deterioration the structure obtained by preliminary heat treatment is shown. Цель работы – исследование структуры зоны термического влияния сварного соединения закалённой на мартенсит высокоуглеродистой низколегированной стали после ручной дуговой сваркой с ускоренным охлаждением.Методы исследования. Для исследования микроструктур использована оптическая и растровая электронная микроскопия. Твердость образцов измеряли с помощью твердомера Виккерса с компьютерным управлением позиционирования и индентирования образца, а также определения диагоналей отпечатков.Результаты. Погруженные в воду (кроме свариваемых кромок) пластины из закалённой на мартенсит высокоуглеродистой низколегированной стали 120Г3С2 и низкоуглеродистой стали 09Г2С сварены ручной дуговой сваркой. Исследована микроструктура сварного соединения. Определены размеры характерных участков зон термического влияния и твердость материала на различном расстоянии от границы сплавления.Научная новизна. Впервые проведена сварка с ускоренным охлаждением в воде высокоуглеродистой стали после закалки на мартенсит без отпуска. Установле но, что в структуре зоны термического влияния твёрдая мартенситная прослойка расположена не вплотную к границе сплавления, а отделена от неё слоем аустенита.Практическая ценность. Показана принципиальная возможность сварки термически обработанных высокоуглеродистых износостойких сталей без нарушения структуры, полученной предварительной термической обработкой. 

Magnetic Losses Evolution of Ferritic Fe-Si Steel Subjected to Temper Rolling at Elevated Temperature

The effects of heat transport phenomena and deformation gradient through the sheet cross-section on the microstructure, texture and magnetic properties of non-oriented Fe-Si steel were investigated. In order to achieve desired conditions for the steel microstructural and textural parameters improvement, a temper rolling process at elevated temperature was examined in combination with subsequent short term annealing, employing fast heating rate in laboratory conditions. The experimental material was represented by conventional medium silicon, vacuum degassed non-oriented steel that was taken directly from industrial line after final annealing. Performed electron back scattered diffraction measurements revealed that the experimental steel, treated by our proposed thermomechanical treatment, was characterized by coarse-grained microstructure with enhanced intensity of rotating cube texture. The magnetic losses of experimental samples were measured in ac magnetic field with 50 Hz frequency on the toroid with external and internal diameters of 25 mm and 15 mm, respectively. These measurements with magnetic field intensity of 2500 A/m showed that the application of our suggested treatment led to clear power losses reduction of the investigated material from initial 9.9 W/kg to 6.4 W/kg, i.e. by more than 35%