Grain-Oriented Electrical Steel Sheet Heating Process
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Solution Overview
Problem
Conventional techniques for improving the iron loss property of grain-oriented electrical steel sheets require excessive rapid heating, leading to increased equipment costs and production costs, as well as issues with temperature variation and magnetic property deviations, limiting further improvement of magnetic properties.
Innovation Solution
A grain-oriented electrical steel sheet with a Si content of 2-5 mass%, plural peaks in the misorientation angle distribution between secondary recrystallized grain and Goss orientation, and a grain size of secondary recrystallized grains not exceeding 15 mm, achieved without excessive rapid heating, incorporating additional elements like C, Mn, Ni, Cr, Cu, P, Sn, Sb, Bi, and Mo.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If excessive rapid heating is applied to refine secondary recrystallized grains and improve iron loss property, then magnetic properties are improved, but equipment cost and production cost increase due to larger induction heating device size and higher current requirements
Solution Approach 1:
The patent changes the heating rate parameter from excessive rapid heating (>100°C/s) to moderate heating rate (10-50°C/s), and introduces a two-stage heating process with different temperature ranges to achieve grain refinement without requiring oversized heating equipment
Solution Approach 2:
The patent performs preliminary recrystallization treatment before final heating, creating a controlled microstructure that enables subsequent grain refinement at lower heating rates, avoiding the need for excessive rapid heating equipment
2Loss of energy
If excessive rapid heating is applied to refine secondary recrystallized grains, then iron loss property is improved, but temperature variation in the steel sheet is widened causing deterioration of sheet threading property
Solution Approach 1:
The patent uses dynamic control of heating rate, starting with moderate heating (10-50°C/s) to maintain temperature uniformity and sheet flatness, then adjusting to different rates at different stages to achieve grain refinement without excessive temperature variation
Solution Approach 2:
The patent performs preliminary recrystallization and microstructure control before final heating, creating a uniform base structure that prevents excessive temperature variation during subsequent heating, maintaining sheet threading properties
3Loss of energy
If excessive rapid heating is applied to refine secondary recrystallized grains, then iron loss property is improved, but the deviation of magnetic properties in a product sheet is widened
Solution Approach 1:
The patent dynamically controls the heating process with multiple stages and varying rates, ensuring uniform heat distribution throughout the sheet to achieve consistent magnetic properties across the product while still refining grains to reduce iron loss
Solution Approach 2:
The patent performs preliminary recrystallization and microstructure uniformization before final heating, creating a consistent base structure that ensures uniform magnetic properties throughout the sheet, reducing property deviation while achieving low iron loss
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces iron loss without excessive rapid heating, enhancing magnetic properties and production efficiency, while maintaining cost-effectiveness and improving sheet threading properties.
Implementation Method 1
increase of Si content... are known to be effective as a method of decreasing the iron loss
Implementation Method 2
crystal orientation thereof is highly accumulated in {110} orientation called Goss orientation
Implementation Method 3
refining of secondary recrystallized grains... is proposed a method wherein a primary recrystallized texture is improved by rapidly heating during decarburization annealing
Data Source
AI summary
When a steel sheet containing Si: 2-5 mass % after cold rolling is subjected to a primary recrystallization annealing and a finishing annealing for secondary recrystallization to form a grain-oriented electrical steel sheet, the primary recrystallization annealing is performed by rapid heating in the heating process and temperature keeping treatment at a certain temperature in the course of the heating to thereby obtain a grain-oriented electrical steel sheet having plural peaks in a distribution of misorientation angle between crystal orientation of secondary recrystallized grains and Goss orientation, wherein misorientation angle of the second smallest peak among the plural peaks is preferably not less than 5° and a grain size of secondary recrystallized grains is not more than 15 mm.