Method for evaluating magnetic anisotropy of non-oriented silicon steel

Abstract

The application discloses a method for evaluating magnetic anisotropy of non-oriented silicon steel, and the method comprises the following steps: sampling at the angles of 0, 2θ, 3θ, …, nθ deviated from the rolling direction of a sample respectively, and obtaining the iron loss values and magnetic induction values at the angles of 0, 2θ, 3θ, …, nθ deviated from the rolling direction respectively; then calculating the iron loss anisotropy T p and the magnetic induction anisotropy T B of the sample according to a formula; comparing the iron loss and the magnetic induction at any angle deviated from the rolling direction with the indexes for representing the magnetic properties of products, i.e. the iron loss and the magnetic induction; meanwhile, θ and n in the evaluation formula are limited according to the test principle of the dispersion degree of the distribution of the internal cause of the magnetic anisotropy, i.e. the texture; and the dispersion degree of the iron loss and the magnetic induction levels of each direction relative to the recognized iron loss and magnetic induction levels can be more directly and comprehensively understood according to the calculation results, i.e. the iron loss anisotropy and the magnetic induction anisotropy, T P and T B The smaller the values of T P and T B are, the smaller the magnetic anisotropy is.

Description

Technical Field

[0001] This invention belongs to the technical field of non-oriented silicon steel products, and specifically relates to a method for evaluating the magnetic anisotropy of non-oriented silicon steel. Background Technology

[0002] Non-oriented silicon steel is the raw material for making the iron cores of various motors. The iron core of a motor is generally composed of a stator and a rotor made of stacked toothed circular laminations. These laminations are made of non-oriented silicon steel sheets by stamping with certain molds. Motors generally work in a rotating state, which requires that non-oriented silicon steel be magnetically isotropic, that is, the performance in every direction is consistent. However, in reality, non-oriented silicon steel is inconsistent in every direction and exhibits anisotropy.

[0003] The national standard GB / T 2521.1-2016, "Cold-rolled electrical steel by all processes - Part 1: Grain-free steel strip (sheet)," specifies the characterization method for magnetic anisotropy as follows: As can be seen from this formula, this method only involves the iron loss in the longitudinal (rolling direction) and transverse (perpendicular to the rolling direction) directions of the product, and does not fully take into account the differences in magnetic properties of non-oriented silicon steel in any direction.

[0004] With the increasing national requirements for energy conservation and emission reduction, non-oriented silicon steel is developing towards higher grades and thinner specifications. Currently, the trial production of higher-grade non-oriented silicon steel with a thickness of 0.18mm to 0.35mm and a Si content of over 3.0% generally employs either a single-stage cold rolling method or a double-stage cold rolling method. Different rolling methods result in different magnetic properties in various directions. In the single-stage cold rolling method, the iron loss generally increases with the angle deviating from the rolling direction (i.e., longitudinal direction), reaching its maximum at 90°. In contrast, the double-stage cold rolling method typically reaches its maximum iron loss at an angle deviating from the rolling direction of 50° to 60°.

[0005] Chinese patent application No. 201810909267.0 discloses a "method for evaluating and characterizing the anisotropy of silicon steel materials". The anisotropy ratio of the magnetic properties at angle θ is calculated using the formula Yθ = bθ / a, where Y represents anisotropy, θ represents the angle between the sample and the rolling direction, bθ is the magnetic properties at angle θ, and a is the magnetic properties along the rolling direction. The anisotropy ratio is calculated using the formula as the average value. variance This method is used to characterize magnetic properties in any direction, but it uses the magnetic properties in the rolling direction as a reference to describe the differences in magnetic properties in various directions. After mathematical conversion using formulas, it is almost the same as the anisotropy characterization method in the national standard. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of current methods for evaluating the magnetic anisotropy of non-oriented silicon steel, and to provide a method for evaluating the magnetic anisotropy of non-oriented silicon steel, so as to more comprehensively and omnidirectionally evaluate the magnetic anisotropy of high-grade non-oriented silicon steel.

[0007] To achieve the above objectives, this invention provides a method for evaluating the magnetic anisotropy of non-oriented silicon steel. Samples are taken from the specimen at deviations of θ, 2θ, 3θ, ..., nθ from the rolling direction, and the iron loss and magnetic flux density values ​​at these deviations are obtained respectively. Then, the method is applied according to the formula... and Calculate the iron loss anisotropy T of the sample p and magnetic anisotropy T B ;

[0008] Where 0°<θ≤20°; n is a positive integer, and n=1+90° / θ; i=1,2,3,……,n.

[0009] Furthermore, P and B refer to the Epstein square requirements in the national standard GB / T 3655-2008 "Method for Measuring Electrical Steel Sheets or Magnetic Sheets Using Epstein Squares" or the iron loss value and magnetic induction value of the sample cut according to the national standard GB / T13789-2008 "Method for Measuring Electrical Steel Sheets or Magnetic Sheets Using a Single-Piece Tester".

[0010] Furthermore, the P i B i For shear specimens along the deviation iθ from the rolling direction, the iron loss and magnetic flux density are tested using the same methods as for P and B.

[0011] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention utilizes the standard variance formula to compare iron loss and magnetic induction at arbitrary angles to the rolling direction with commonly used indicators characterizing the magnetic properties of products, namely iron loss and magnetic induction. Simultaneously, based on the testing principle of the inherent cause of magnetic anisotropy—the degree of dispersion in texture distribution—the evaluation formula's θ and n are constrained. The calculation results provide a more intuitive and comprehensive understanding of the dispersion of iron loss and magnetic induction levels in each direction relative to generally accepted levels, i.e., iron loss anisotropy and magnetic induction anisotropy, T. P and T B The smaller the value, the smaller the magnetic anisotropy. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the sample sampling angle for the present invention. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0014] like Figure 1 The method involves preparing 24 square standard samples (30mm × 320mm) with deviations from the rolling direction at intervals of 10°, 20°, ... . Iron loss P is then measured on both the square standard samples and the Epstein square samples. 1.5 / 50 With magnetic induction intensity B 50 With θ = 10° and n = 10, the results are shown in Table 1.

[0015] Table 1 Test Results

[0016]

[0017] Substitute the above data into the formula and Calculate the iron loss anisotropy T of the sample p and magnetic anisotropy T B :

[0018]

Claims

1. A method for evaluating the magnetic anisotropy of non-oriented silicon steel, characterized in that: Samples were taken from the specimen at deviations of θ, 2θ, 3θ, ..., nθ from the rolling direction, and the iron loss and magnetic flux density values ​​at these deviations were obtained respectively. Then, the formula was applied... and Calculate the iron loss anisotropy T of the sample p and magnetic anisotropy T B ; Where 0°<θ≤20°; n is a positive integer, and n=1+90° / θ; i=1,2,3,……,n; P and B refer to the iron loss value and magnetic flux density value of the sample cut according to the Epstein square requirements in the national standard GB / T 3655-2008 "Method for Measuring the Magnetic Properties of Electrical Steel Sheets (Strips) Using Epstein Squares"; or P and B refer to the iron loss value and magnetic flux density value of the sample cut according to the national standard GB / T 13789-2008 "Method for Measuring the Magnetic Properties of Electrical Steel Sheets (Strips) Using a Single-Piece Tester". i B i The iron loss and magnetic flux density values ​​of the shear specimens along the deviation iθ from the rolling direction are tested using the same method as the P and B test methods.

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