Texture Evolution during High Temperature Plane Strain Compression of High Silicon Steels

2007 ◽  
Vol 553 ◽  
pp. 15-20 ◽  
Author(s):  
Pablo Rodriguez-Calvillo ◽  
Yvan Houbaert
Keyword(s):  
Magnetic Properties ◽  
High Temperature ◽  
Plane Strain ◽  
Silicon Content ◽  
Texture Evolution ◽  
Plane Strain Compression ◽  
Compression Tests ◽  
Average Grain Size ◽  
High Silicon ◽  
Average Size

High silicon steel is used for electrical applications because its electrical resistivity is increased and the magnetostriction is reduced. A silicon content up to 6.5 wt.-% gives excellent magnetic properties. The improvement of the magnetic properties stays in contrast with the lack of ductility of these alloys, making their thermo-mechanical processing difficult. The optimum final microstructure and texture depends on the final application of the material: extremely big grains with a Goss orientation ({110} <001>) are desired in transformers and grains with an average size of 100 -m and cube component ({100} <001>) are used in electrical motors. A series of plane strain compression (PSC) tests were performed on 3 electrical steels, with a silicon content from 1.8 to 4.1 wt.-%, in a temperature range of 800 to 1100°C, strain rates between of 0.5 and 5 s-1. Reductions and time between deformation and quenching were also varied in order to study the recrystallisation progress. Apparent activation energies for hot working, calculated using the hyperbolic sine equation, was in good agreement with literature and higher than the activation energy for self diffusion in iron. These values increase with the silicon content. The high temperature texture evolution was investigated by means of electron back scattering Diffraction (EBSD) technique, which allows the quantification of important texture components in function of the thermo-mechanical parameters applied during hot rolling and the plane strain compression tests. The hot rolled microstructures have shown an average grain size of 140 -m and a texture with a maximum on the cube fibre ({001} <-1-10>). The conventional α (<110> // RD) / γ (<111> // ND) fibre texture was developed after plane strain compression and their intensities depend on the deformation temperature and reduction. A similar tendency was observed for the fraction of static recrystallised grains.

A Study of Texture Evolution during Deformation and Annealing in Fe 3 wt.-% Si by Orientation Contrast Microscopy

2007 ◽  
Vol 550 ◽  
pp. 539-544 ◽  
Author(s):  
Pablo Rodriguez-Calvillo ◽  
Roumen H. Petrov ◽  
Yvan Houbaert ◽  
Leo Kestens
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Plane Strain ◽  
Lattice Structure ◽  
Texture Evolution ◽  
Constant Strain Rate ◽  
Plane Strain Compression ◽  
Compression Tests ◽  
Electrical Steels ◽  
Average Grain Size

Electrical steels, in particular Fe-Si alloys, are used as magnetic flux carrier in transformers and motors because of their excellent magnetic properties. They owe these magnetic properties in part to the presence of specific texture components such as the Goss ({110} <001>) or the cube components ({001} <010>), but also to the chemical composition which is optimum with 6.5 wt. % Si. This high silicon content provides a stable BCC lattice structure to the alloy over the entire solid state domain, but also renders the material more brittle. This embrittlement, which is induced by ordering phenomena, makes it impossible to produce the alloy in a conventional rolling process unless a specific thermomechanical route at high temperature is applied. In order to examine the working behaviour of high Si electrical steels, a series of room temperature plane strain compression tests was carried out on a Fe-3%Si alloy in hot band condition. The samples were compressed with a constant strain rate of 20 s-1 to a reduction of 10, 35 and 70% and subsequently annealed for different times at 800 and 900°C in an electrical furnace without protecting atmosphere. The hot rolled microstructure displayed an average grain size of 195 7m and the texture showed on the cube component ({001} <010>) of maximum 5x random levels. After plane strain compression the samples developed the conventional α (<110> // RD) / γ (<111> // ND) fibre texture by plastic shear which was also accommodated, in part, by mechanical twinning. With regard to the annealed material, it was observed that the recrystallisation started in grains with the higher stored energy and within the shear bands. After a reduction of 70% the samples that were annealed at 800°C for 4 hours displayed an average grain size of 27 7m and a relative maximum of 4x random on the cube component. Also other less intense components such as the rotated cube ({001} <110>) and the Goss ({110} <001>) were present in the annealing texture. The samples that were annealed at 900°C, after a reduction of 70%, were characterized by an average grain size of 36 7m and by the appearance of the {111} <121> γ fibre component with an intensity of 4.7.

Texture Formation Behaviour during High-Temperature Plane Strain Compression Deformation in AZ91 Magnesium Alloy

2018 ◽  
Vol 941 ◽  
pp. 1198-1202
Author(s):  
Dong Keun Han ◽  
Min Soo Park ◽  
Han Sang Kwon ◽  
Kwon Hoo Kim
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Plane Strain ◽  
Texture Evolution ◽  
Plane Strain Compression ◽  
Deformation Condition ◽  
Rolled Plate ◽  
Pole Density ◽  
Texture Formation ◽  
Compression Tests

In previous study, it was investigated texture formation behaviour of high-temperature plane strain compression test at 723K, under a strain rate of 5.0. It was found that the main texture component and it was sharpness vary depending on deformation conditions. To clarify the characteristic of texture formation behaviour, it is necessary to investigate at various deformation condition. Therefore, in this study, is investigating the influence or texture formation behaviour and strain, strain rate at 673K. Three kinds of specimens with different initial textures were machined out from a rolled plate having a <0001> texture. The plane strain compression tests were conducted at a temperature 673K, and a strain rate of 5.0, with strain between-0.4 to-1.0. After compression tests, the specimens were immediately quenched in oil. The texture evolution was conducted by the Schulz reflection method using Cu Kα radiation and EBSD. Before the deformation, {0001} of specimen A was accumulated in the center of pole figure. The {0001} of specimen B was accumulated at the RD direction. The {0001} of specimen C was accumulated TD direction. As a result, work softening is observed in all the cases at the true stress – true strain curve for three types of specimens. After deformation, the maximum pole density of increases with increasing strain. In this study, it was found that the stable orientation was (0001)<100> and (0001)<110> during deformation.

Characteristics of the Deformed and Recrystallised Grains Obtained after Hot Plane Strain Compression of a Model Fe-30wt%Ni Alloy

2004 ◽  
Vol 467-470 ◽  
pp. 21-26 ◽  
Author(s):  
F. Bai ◽  
P. Cizek ◽  
Eric J. Palmiere ◽  
Mark W. Rainforth
Keyword(s):  
Plane Strain ◽  
Crystallographic Texture ◽  
Hot Deformation ◽  
Electron Backscatter Diffraction ◽  
Orientation Dependence ◽  
Plane Strain Compression ◽  
Formation Mechanisms ◽  
Subgrain Structure ◽  
Compression Tests ◽  
Texture Characteristics

The development of physically-based models of microstructural evolution during hot deformation of metallic materials requires knowledge of the grain/subgrain structure and crystallographic texture characteristics over a range of processing conditions. A Fe-30wt%Ni based alloy, retaining a stable austenitic structure at room temperature, was used for modelling the development of austenite microstructure during hot deformation of conventional carbon-manganese steels. A series of plane strain compression tests was carried out at a temperature of 950 °C and strain rates of 10 s-1 and 0.1 s-1 to several strain levels. Evolution of the grain/subgrain structure and crystallographic texture was characterised in detail using quantitative light microscopy and highresolution electron backscatter diffraction. Crystallographic texture characteristics were determined separately for the observed deformed and recrystallised grains. The subgrain geometry and dimensions together with the misorientation vectors across sub-boundaries were quantified in detail across large sample areas and the orientation dependence of these characteristics was determined. Formation mechanisms of the recrystallised grains were established in relation to the deformation microstructure.

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