Non-oriented silicon steel sheet having excellent core loss and its production method

Abstract

A non-oriented electrical steel sheet, characterized in that the number density of inclusions contained in the steel sheet with an equivalent spherical diameter of less than 100 nm is 1 x 1010 [pieces / mm3] or less; furthermore, in mass %, Contains C: 0.01% or less, Si: 0.1% to 7.0%, Al: 0.1% to 3.0%, Mn: 0.1% to 2.0%, REM: 0.0003% to 0.05%, Ti: 0.02% or less, S: 0.005 % or less, and N: 0.005% or less, the balance is composed of Fe and unavoidable impurities, and the mass % of Al represented by [Al], the mass % of N represented by [N], and the mass % of N represented by [Ti ] The mass % of Ti represented by ] satisfies the following formula (1).

Description

technical field [0001] The present invention relates to a non-oriented electrical steel sheet used for an iron core of a motor and a manufacturing method thereof, and to a non-oriented electrical steel sheet having excellent iron loss, particularly iron loss after stress relief annealing, and a manufacturing method thereof. Background technique [0002] It is well known that the iron loss of the non-oriented electrical steel sheet is the smallest when the grain diameter is about 150 μm. Therefore, from the viewpoint of product characteristics, simplification of the manufacturing process, and improvement of productivity, it is desired to obtain a steel sheet with better grain growth characteristics in the final annealing. [0003] Furthermore, when the user punches the iron core, the finer the crystal grains, the higher the punching accuracy during the punching process, and the crystal grain diameter is preferably 40 μm or less, for example. In this way, the requirements of ...

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Problems solved by technology

[0013] However, high purification in the steelmaking stage will inevitably lead to an increase in steelmaking costs, so it is not preferred

In addition, in the annealing treatment such as the final annealing of the finished plate or the stress relief annealing after blanking, and when the treatment conditions develop toward low temperature and short time, the method of adding elements mentioned above is very effective for grain growth. It is not enough to develop in a favorable direction and to reduce the iron loss

[0014] It should be noted that even if the number density of inclusions is adjusted within the recommended range disclosed in JP-A-2001-271147, when the stress relief annealing is carried out at a low temperature and a short time, the growth of grains may still fail. Improved

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