Grain-Oriented Steel Sheet Low-Temperature Slab Heating
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Solution Overview
Problem
Conventional methods for producing grain-oriented electrical steel sheets require high temperature slab heating, leading to increased energy costs and deterioration of magnetic properties due to excessive carbon content, which necessitates decarburization annealing, limiting productivity and yield.
Innovation Solution
Minimizing carbon content in the steel sheet to 0.0005% to 0.005% and adjusting the silicon content to 2.0% to 4.5%, along with controlling the cooling rate and heating rate during annealing processes, to enhance the growth of Goss-oriented grains and improve magnetic properties without the need for high temperature slab heating or decarburization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high temperature slab heating is performed to achieve uniform inhibitor distribution, then the inhibitor distribution becomes uniform and fine, but the slab structure becomes excessively coarse which impedes secondary recrystallization and deteriorates magnetic properties
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperature (1300°C or higher) to low temperature (1200°C or lower) slab heating, which prevents excessive coarsening of the slab structure while still achieving sufficient inhibitor distribution. This parameter change resolves the contradiction by finding an optimal temperature window that satisfies both inhibitor distribution and magnetic property requirements
2Stability of the object's composition
If high temperature slab heating is performed, then inhibitor distribution is improved, but energy consumption increases and decarburization annealing is required
Solution Approach 1:
The patent reduces the slab heating temperature to 1200°C or lower, which significantly reduces energy consumption compared to conventional high temperature heating (1300°C or higher), while still achieving the necessary inhibitor distribution through optimized heating parameters and material composition
3Stability of the object's composition
If high temperature slab heating is performed, then inhibitor distribution is improved, but additional decarburization annealing step is required which reduces productivity
Solution Approach 1:
The patent optimizes the slab heating temperature to 1200°C or lower and controls the heating time and material composition to achieve sufficient inhibitor distribution without causing excessive carbon content, thereby eliminating the need for additional decarburization annealing steps and improving manufacturing efficiency
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 results in grain-oriented electrical steel sheets with improved magnetic flux density and reduced iron loss, achieving magnetic flux density of 1.92 T or more and iron loss of 0.70 W/kg or less, while reducing manufacturing costs and increasing productivity.
Implementation Method 1
it is necessary to contain C of around 0.03 % to 0.08 % in the material for the purpose of using the α-γ transformation during hot rolling to break the coarse slab structure
Implementation Method 2
it is important to form a predetermined microstructure in the texture of the primary recrystallized sheet
Implementation Method 3
grain oriented electrical steel sheets having crystal grains in accord with the {110} orientation through secondary recrystallization annealing
Data Source
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AI summary
Provides is a method of producing a grain oriented electrical steel sheet by heating a steel slab having a composition containing by mass% C: 0.0005 % to 0.005 %, Si: 2.0 % to 4.5 %, Mn: 0.005 % to 0.3 %, S and/or Se (in total): 0.05 % or less, sol.Al: 0.010 % to 0.04 %, N: 0.005 % or less, the balance being Fe and incidental impurities, then subjecting the slab to hot rolling to obtain a hot rolled sheet, then optionally subjecting the hot rolled sheet to hot band annealing and subsequent cold rolling once, or twice or more with intermediate annealing performed therebetween to obtain a cold rolled sheet with final sheet thickness, then subjecting the cold rolled sheet to primary recrystallization annealing and subsequent secondary recrystallization annealing, in which the aging index AI of the steel sheet before final cold rolling is set to 70 MPa or less to effectively grow Goss-oriented grains to thereby obtain a grain-oriented electrical steel sheet with good magnetic properties, without the restriction of containing a relatively large amount of C.