Recent developments in semiprocessed cold rolled magnetic lamination steel

Hilinski, Erik J.

doi:10.1016/j.jmmm.2006.02.114

Cited by 10 publications

(6 citation statements)

References 10 publications

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“…After cold rolling, semi-processed steel coils are generally temper rolled (i.e., skin passed) and then they are subjected to final recrystallization annealing to improve their punchability, facilitate strain-induced grain growth during the annealing at final producers of electromechanical machines. It has been estimated that the temper rolling introduces a soft deformation into the material, which accounts for 5–10% reduction in its thickness [12,13,14]. Thus, the semi-finished steels possess some extent of stored deformation energy, accumulated in dislocation structures, which can provide a sufficient driving force for a selective grain growth process, also known as strain-induced grain boundary migration phenomenon [15].…”

Section: Introductionmentioning

confidence: 99%

Improving the Magnetic Properties of Non-Oriented Electrical Steels by Secondary Recrystallization Using Dynamic Heating Conditions

et al. 2019

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In the present work, we have used unconventional short-term secondary recrystallization heat treatment employing extraordinary high heating rate to develop coarse-grained microstructure with enhanced intensity of rotating cube texture {100}<011> in semi-finish vacuum degassed non-oriented electrical steels. The soft magnetic properties were improved through the increase of grains size with favourable cube crystallographic orientation. The appropriate final textural state of the treated experimental steels was achieved by strain-induced grain boundary migration mechanism, activated by gradient of accumulated stored deformation energy between neighbouring grains after the application of soft cold work, combined with steep temperature gradient during subsequent heat treatment under dynamic heating conditions. The materials in our experimentally prepared material states were mounted on the stator and rotor segments of electrical motors and examined for their efficiency in real operational conditions. Moreover, conventionally long-term heat treated materials, prepared in industrial conditions, were also tested for reference. The results show that the electrical motor containing the segments treated by our innovative approach, exhibits more than 1.2% higher efficiency, compared to the motor containing conventionally heat treated materials. The obtained efficiency enhancement can be directly related to the improved microstructural and textural characteristics of our unconventionally heat treated materials, specifically the homogenous coarse grained microstructure and the high intensity of cube and Goss crystallographic texture.

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Section: Introductionmentioning

confidence: 99%

Improving the Magnetic Properties of Non-Oriented Electrical Steels by Secondary Recrystallization Using Dynamic Heating Conditions

et al. 2019

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“…The stress relief heat treatment is realized at slow heating rates and maximum annealing temperature of about 800 °C. The scheme of long-term heat treatment is very similar to the process of secondary recrystallization heat treatment, which is commonly used for the semi-finished electrical steels [17]. However, in contrast to semi-finished steel, which is characterized by pronounced microstructural evolution, the microstructure of fully finished steel does not exhibit any significant changes after the heat treatment (see Figure 3b).…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted that NO electrical steel sheets are generally divided into two categories, namely the fully processed (i.e., fully finished) and semi-processed (i.e., semi-finished) grades. The semi-processed electrical steels are finished to their final thickness by the steel producer and then their final magnetic properties are achieved during the final heat treatment at the end-consumers after different cutting processes [17]. The fully finished NO steels are characterized by their final sheet thickness, microstructure, magneto-crystalline texture, and specific magnetic properties, which have been adjusted through hot band annealing, cold rolling, and final annealing of thin steel strip.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Power Losses in Bending Rolled Fully Finished NO Electrical Steel Treated under Unconventional Annealing Conditions

et al. 2019

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Currently, the non-oriented (NO) iron-silicon steels are extensively used as the core materials in various electrical devises due to excellent combination of their mechanical and soft magnetic properties. The present study introduces a fairly innovative technological approach applicable for fully finished NO electrical steel before punching the laminations. It is based on specific mechanical processing by bending and rolling in combination with subsequent annealing under dynamic heating conditions. It has been revealed that the proposed unconventional treatment clearly led to effective improvement of the steel magnetic properties thanks to its beneficial effects involving additional grain growth with appropriate crystallographic orientation and residual stress relief. The philosophy of the proposed processing was based on employing the phenomena of selective grain growth by strain-induced grain boundary migration and a steep temperature gradient through the cross-section of heat treated specimens at dynamic heating conditions. The stored deformation energy necessary for the grain growth was provided by plastic deformation induced within the studied specimens during the bending and rolling process. The magnetic measurements clearly show that the specimens treated according to our approach exhibited more than 17% decrease in watt losses in comparison with the specimens treated by conventional heat treatment leading only to stress relief without additional grain growth.

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“…This production path can be associated with the manufacturing of semiprocessed grades of NO steels which are produced by a similar approach. It is known that the magnetic quality of the texture may largely benefit from an annealing treatment carried out on a temperrolled material [9][10][11][12].…”

Section: Two-stage Cold Rollingmentioning

confidence: 99%

Texture Control During the Manufacturing of Nonoriented Electrical Steels

Kestens

Jacobs

2008

Texture, Stress, and Microstructure

133

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Methods of modern quantitative texture analysis are applied in order to characterize the crystallographic texture of various non-oriented electrical steel grades in view of their relation with the magnetic properties of the steel sheet. A texture parameter is defined which quantifies the density of‹100›easy magnetic directions in the sheet planes. An extensive correlation study revealed the relation of this parameter with the hysteresis losses, determined at an induction of 1.5 T, and with the induction measured at an applied external field of 25 A/cm. It is shown that the latter magnetic property is the more texture dependent, whereas the former one is more sensitive to the grain size of the steel. Also various strategies for texture control are critically reviewed. It is shown that the conventional manufacturing process only provides poor tools for optimizing the texture of the final product. In order to obtain a quantum-leap improvement of the magnetic quality of the texture, in combination with other important microstructural features, nonstandard processing strategies are required, such as cross-rolling, two-stage cold rolling, or surface annealing.

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Recent developments in semiprocessed cold rolled magnetic lamination steel

Cited by 10 publications

References 10 publications

Improving the Magnetic Properties of Non-Oriented Electrical Steels by Secondary Recrystallization Using Dynamic Heating Conditions

Improving the Magnetic Properties of Non-Oriented Electrical Steels by Secondary Recrystallization Using Dynamic Heating Conditions

Evolution of Power Losses in Bending Rolled Fully Finished NO Electrical Steel Treated under Unconventional Annealing Conditions

Texture Control During the Manufacturing of Nonoriented Electrical Steels

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