Grain-Oriented Electrical Steel Annealing for Co Oxide Layer Control
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Solution Overview
Problem
Existing methods for manufacturing grain-oriented electrical steel sheets face challenges in achieving high magnetic flux density and low core loss due to issues with grain growth suppression and the thickening of Co in metal oxide layers during the primary recrystallization annealing process.
Innovation Solution
A method for manufacturing grain-oriented electrical steel sheets involves controlling the atmosphere gas during the primary recrystallization annealing process to suppress the thickening of Co in the metal oxide layer, thereby improving magnetism. This includes specific compositions of the steel sheet substrate and the metal oxide layer, as well as precise control of the oxidization abilities during the annealing stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the atmosphere gas is not controlled during primary recrystallization annealing, then the manufacturing process is simple, but the Co in the metal oxide layer thickens and magnetic characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the oxidization ability parameter during different temperature rising stages of primary recrystallization annealing. Specifically, the oxidization ability is controlled within 0.7-2.0 during the first temperature rising stage (room temperature to 710-770°C), 0.05-0.6 during the second temperature rising stage (710-770°C to 830-890°C), and 0.3-0.6 during the soaking stage (830-890°C to 900°C). This parameter control prevents excessive Co diffusion to the metal oxide layer while maintaining manufacturing feasibility.
2Manufacturing precision
If MnS is used as grain growth inhibiting agent, then the manufacturing process is simple, but the magnetic flux density is not high enough and core loss is high
Solution Approach 1:
The patent changes the compositional parameters by adding specific amounts of Sb (0.01-0.05 wt%), Sn (0.03-0.08 wt%), and Cr (0.01-0.2 wt%) to replace MnS as grain growth inhibiting agents. This compositional change enables high magnetic flux density while maintaining manufacturing feasibility through controlled annealing processes.
Solution Approach 2:
The patent uses a composite grain growth inhibiting system combining Sb, Sn, and Cr elements instead of a single MnS agent. This composite approach provides effective grain growth suppression while achieving high magnetic flux density and low core loss, resolving the contradiction between performance and manufacturing simplicity.
3Manufacturing precision
If Mn, Se, and Sb are used as grain growth inhibiting agents, then high magnetic flux density is achieved, but the material is hardened and manufacturing cost increases
Solution Approach 1:
The patent adjusts the compositional parameters by removing Se from the grain growth inhibiting agent combination and using only Sb (0.01-0.05 wt%) and Sn (0.03-0.08 wt%). This parameter change achieves high magnetic flux density while avoiding the hardening effect caused by Se, thus maintaining material ductility and reducing manufacturing cost.
4Manufacturing precision
If Sn and Cr are added in complex way with strict temperature control, then low core loss and high magnetic flux density are achieved, but the oxidation layer becomes very thick and decarburization and nitrification become difficult
Solution Approach 1:
The patent controls the oxidization ability parameter during primary recrystallization annealing to prevent excessive oxidation layer formation. By maintaining oxidization ability within 0.7-2.0 during the first temperature rising stage, 0.05-0.6 during the second temperature rising stage, and 0.3-0.6 during soaking, the oxidation layer thickness is controlled, enabling subsequent decarburization and nitrification processes to proceed effectively while achieving low core loss and high magnetic flux density.
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
The method effectively improves the magnetic characteristics of the grain-oriented electrical steel sheets by maintaining a high magnetic flux density and low core loss, while also ensuring the integrity of the Goss texture and preventing the deterioration of the magnetic properties.
Implementation Method 1
suppressing thickening of Co in a metal oxide layer by controlling atmosphere gas in a primary recrystallization annealing process
Implementation Method 2
controlling atmosphere gas in a primary recrystallization annealing process
Implementation Method 3
primary recrystallization annealing process
Implementation Method 4
primary recrystallization annealing process
Data Source
AI summary
A grain-oriented electrical steel sheet according to an embodiment of the present invention includes: an electrical steel sheet substrate including, by wt %, 2.0 to 6.0% of Si, equal to or less than 0.005% of C (excluding 0%), 0.01 to 0.05% of Sb, 0.03 to 0.08% of Sn, 0.01 to 0.2% of Cr, and 0.0003 to 0.097% of Co, and including a remainder of Fe and inevitable impurities; and a metal oxide layer disposed on a surface of the electrical steel sheet substrate, wherein the metal oxide layer includes 0.0005 to 0.25 wt % of Co.