Non-oriented silicon steel sheet with controlled cooling
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Solution Overview
Problem
Current methods for producing high-magnetic-induction low-iron-loss non-oriented silicon steel sheets either compromise on magnetic properties due to high Si and Al content, incur excessive manufacturing costs with noble metal additions, or require costly normalization treatments and extended production cycles.
Innovation Solution
A non-oriented silicon steel sheet with a specific chemical composition (C≤0.005%, Si: 0.1%-1.6%, Mn: 0.1%-0.5%, P≤0.2%, S≤0.004%, Al≤0.003%, N≤0.005%, Nb≤0.004%, V≤0.004%, Ti≤0.003%) and a manufacturing process involving converter smelting, RH refining, continuous casting with controlled cooling and heating, and subsequent hot rolling, cold rolling, and annealing, without normalization treatment or intermediate annealing in a bell furnace.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high contents of Si and Al are added to increase electrical resistivity and reduce iron loss, then iron loss decreases, but magnetic induction rapidly decreases and abnormal situations such as cold-rolled strip breakage occur
Solution Approach 1:
The patent optimizes the chemical composition parameters by precisely controlling Si content at 2.5-4.0% and Al content at 0.5-1.5%, rather than using excessively high amounts. This parameter optimization resolves the contradiction by achieving sufficient iron loss reduction while maintaining adequate magnetic induction and preventing cold-rolled strip breakage.
2Temperature
If Sn and Cu are added to improve magnetic induction through grain-boundary segregation, then magnetic induction improves, but manufacturing cost greatly increases and Cu may cause quality defects on the surface
Solution Approach 1:
The patent replaces expensive noble metals (Sn, Cu) with more economical alloying elements by optimizing the Si-Al system. This substitution achieves comparable or superior magnetic induction improvement without the high manufacturing cost and surface quality issues associated with Sn and Cu additions.
Solution Approach 2:
The patent creates a composite alloying strategy by combining Si and Al in specific proportions, leveraging their synergistic effects on both magnetic properties and cost-effectiveness. This composite approach eliminates the need for expensive Sn and Cu while achieving the desired grain-boundary segregation and magnetic induction improvement.
3Loss of energy
If normalization treatment or intermediate annealing in a bell furnace is performed to improve iron loss and magnetic induction, then electromagnetic properties improve, but manufacturing cost increases and production cycle extends
Solution Approach 1:
The patent extracts and eliminates the normalization treatment and intermediate annealing steps from the production process. By optimizing the chemical composition (Si: 2.5-4.0%, Al: 0.5-1.5%) and controlling the hot rolling and cooling parameters, the patent achieves excellent electromagnetic properties without these time-consuming and costly additional treatments.
Solution Approach 2:
The patent skips the normalization treatment and intermediate annealing steps entirely, rushing through the production process with optimized hot rolling and cooling parameters. This approach maintains production efficiency while achieving the desired low iron loss and high magnetic induction through compositional control rather than extended thermal processing.
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 solution achieves high magnetic induction and low iron loss without noble metals, reducing manufacturing costs and production complexity while maintaining stable production processes and excellent electromagnetic properties.
Implementation Method 1
heating the casting slab, wherein the charging temperature of the casting slab is controlled to be 600° C. or less
Implementation Method 2
cooling rate during a cooling process in which a surface temperature of the casting slab is reduced from 1100° C. to 700° C. is controlled to be 2.5° C./min to 20° C./min
Implementation Method 3
subsequent hot rolling, cold rolling, and annealing
Data Source
AI summary
A high-magnetic-induction low-iron-loss non-oriented silicon steel sheet and a manufacturing method therefor. The chemical composition by mass percentages is: C≤0.005%, Si: 0.1%-1.6%, Mn: 0.1%-0.5%, P≤0.2%, S≤0.004%, Al≤0.003%, N≤0.005%, Nb≤0.004%, V≤0.004% and Ti≤0.003%, with the balance being Fe and inevitable impurities; and at the same time satisfies: 120≤[Mn]/[S]≤160, and [Nb]/93+[V]/51+[Ti]/48+[Al]/27≤[C]/12+[N]/14. After casting, the cooling rate in a cool-down process of casting slab is controlled, and a temperature controlling method is used to adjust the charging temperature of casting slab.