Non-grain oriented electrical steel and method for manufacturing same

Abstract

A non-grain oriented electrical steel according to an embodiment of the present invention comprises, in weight, 0.004% or less (excluding 0%) of C, 2.5-4.0% of Si, 0.1% or less (excluding 0%) of P, 0.3-2.0% of Al, 0.003% or less (excluding 0%) of N, 0.003% or less (excluding 0%) of S, 0.15-2.5% of Mn, 0.5% or less (excluding 0%) of Cr, and the balance Fe and unavoidable impurities, wherein the non-grain oriented electrical steel satisfies expression 1 below and has an average crystal grain size of 20 [mu]m or less. [Expression 1] [Mn]>=1450*[S]-0.8 (wherein, [Mn] and [S] represent the contents (wt%) of Mn and S, respectively.).

Description

technical field [0001] The invention relates to a non-oriented electrical steel sheet and a manufacturing method thereof. Specifically, the present invention relates to a non-oriented electrical steel sheet and its manufacturing method. By adding appropriate amounts of Mn and S elements to the steel sheet and controlling the grain size to be small, it is possible to achieve high-strength properties and energy efficiency at the same time. low iron loss magnetic properties. Background technique [0002] Recently, with increasing focus on efficient use of energy, efforts are being made to improve motors used in large generators or in electrical equipment such as environmentally friendly vehicles such as hybrid electric vehicles (HEV; Hybrid Electric Vehicle) or electric vehicles (EV; Electric Vehicle) s efficiency. As part of this, efforts are being made to achieve faster rotation speeds than ordinary motors through frequency modulation, like BLDC motors. [0003] In particu...

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Problems solved by technology

[0006] However, for the technology of forming structures other than ferrite, due to the presence of pearlite, martensite and austenite non-magnetic abnormal structures inside the steel, the iron loss and magnetic flux density decay rapidly, and there is The defect of rapid loss of efficiency

The technology of adding special alloy elements also suffers from the problem of rapid magnetic decay and is limited depending on the application

In addition, the technology of controlling the grain size before cold rolling to a large size is not effective in high-strength electrical steel sheets with many unrecrystallized structures, and there is a problem that it is difficult to effectively improve magnetic properties

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