Marco Antônio da Cunha

Effect of the annealing temperature on the structure and magnetic properties of 3% Si non-oriented steel

Abstract 3%Si non-oriented steel samples cold rolled in two stages with an intermediate annealing were finally annealed in the temperature range 540–980°C. Recovery and recrystallization resulted in significant improvement of magnetic properties. Texture improvement on further grain growth resulted in simultaneous decrease of core loss and increase of polarization and permeability.

Influence of grain size and additions of Al and Mn on the magnetic properties of non-oriented electrical steels with 3 wt. (%) Si

The influence of hot-band grain size and additions of aluminum and manganese on the magnetic properties of non-oriented grain (NOG) low-carbon electrical steel with about 3 wt. (%) Si were investigated using optical microscopy and X ray diffraction. The addition of manganese resulted in larger grains after final annealing. Coarse grains in the hot-band and addition of Mn led to a Goss orientation component after final annealing, which resulted in an increase in the magnetic permeability.

Effect of the Annealing Temperature on the Structure and Magnetic Properties of 2% Si Steel

To study the effect of the annealing temperature on the structure and magnetic properties of a 2%Si non-oriented steel cold rolled samples were submitted to final annealing in the temperature range of 540 °C to 980 °C in hydrogen atmosphere. The samples had received cold rolling reduction of 75% to a final thickness of 0.50 mm. Recovery and recrystallization resulted in significant improvement of magnetic properties, with decrease of iron loss (W1.5) and increase of polarisation (J50) and relative permeability (µ1.5). On further grain growth, after recrystallization, there was simultaneous decrease of iron loss, polarisation and relative permeability. Texture evolution on grain growth accounts for the observed decrease of J50 and µ1.5. The beneficial effect of increasing grain size on core loss overcomes the detrimental effect of texture resulting in decrease of W1.5.

Evolution of Non-Oriented Silicon Steel Texture on Recrystallization and Grain Growth

The evolution of annealing texture of non-oriented grain silicon steel as a function of annealing temperature was investigated from hot rolled samples taken from industrial production. Hot band samples were annealed at 900°C, cold rolled to final thickness of 0.5mm in a single stage cold rolling process or in two stages with intermediate annealing at 900°C, and final annealed in the temperature range from 540°C to 980°C. The results show that the [001]||RD fibre is an important recrystallization texture component, but it may be consumed by further grain growth and become a minor component. The effect of grain growth in the temperature range investigated seems to be that of strengthening the main components at the expenses of the others. The results suggest that to avoid the reduction of the [001]||RD fibre on grain growth a volume fraction ratio between the texture components (111)[112] and (110)[001] close to unity is necessary after recrystallization. This can be obtained under conditions that enhance [001]||RD fibre on recrystallization, such as: strong [111]ND fibre in the deformation texture, large initial grain size and enhanced grain boundary mobility, by proper composition and purity.

The Influence of Hot Rolling Finishing Temperature on the Structure and Magnetic Properties of 2.0%Si Non-Oriented Silicon Steel

Rougher bar samples of 2.0%Si and 0.25%Al Non Oriented Grain with 25mm thickness were rolled to 2.3mm in a pilot reversible mill with temperatures ranging from 920 to 1120°C and processed until the final annealing to study the evolution of grain size and crystallographic orientation. The results showed that higher hot rolling finishing temperature results in larger hot band grain size, but the texture, composed mainly by alpha, gamma, {100} , and eta fibers suffers little effect. As a consequence, after final annealing, an increase of fraction of the grains with eta fiber orientation and a reduction of grains with gamma fiber orientation are observed, improving the magnetic induction. The final grain size decreases with hot rolling finishing temperatures above 1040°C in spite of increasing hot band grain size, deteriorating the core loss results. This was explained by the increasing of shear bands when the grain size prior to cold rolling increases. More shear bands generates more sites for nucleation on recrystallization, then smaller final grain size results. The Goss orientation is generated mainly in the sites inside shear bands. The increasing of prior grain size also increases the fraction of grains with Goss orientation after final annealing and its fraction increases suddenly when the hot rolling finishing temperature achieves 1040°C, supporting that affirmation.

Texture Optimization in Non-Oriented Electrical Steels: The Role of the Goss Texture Component

The non-oriented electrical steels, produced with different processing procedures, base their magnetic property improvement mainly on the increase of the Goss component. This paper relates the anisotropy of magnetic properties to texture, describes the texture evolution in both the Fully-processed and the Semi-processed classes of electrical steels.

Properties of NGO 3% Silicon Steel Asymmetrically Cold Rolled

The effects of asymmetric and conventional deformations and annealing on the microstructure of non-grain-oriented (NGO) 3 wt% silicon steel were analyzed by x-ray diffraction, optical microscopy and magnetometry. The results suggest that pure asymmetric rolling tends to lessen magnetic losses. However, intermediate annealing resulted in lower planar anisotropy, which could be estimated from the magnetic anisotropy theory. In this work, it was shown that this theory is able to predict the J50 magnetic polarization values using crystallographic texture.

Effect of Inter-Pass Ageing during Cold Rolling on Magnetic Properties of Fe-3%Si

The effects of inter-pass ageing temperature during cold rolling on structure, magnetic properties and mechanical properties of high permeability grain oriented electrical steel was studied. The samples were processed in a single-stage cold rolling to 0.27 mm thickness, with 88 % reduction, without and with inter-pass ageing treatment in order to determine the magnetic properties. To determine the changes in mechanical properties due to strain ageing, the samples underwent overlapped ageing, after pre-strain by rolling, under the same conditions of inter-pass ageing and then were subjected to tensile test. The effect of strain ageing was more pronounced in the thickness of 0.7 mm and the largest variation in yield strength was at 200°C in all evaluated thicknesses. At this temperature the largest amount of {110} orientation after primary recrystallization was also observed, as well as the lowest final grain size and consequently the best results of core loss. The magnetic induction had almost no alterations.