Non-oriented electrical steel sheet manufacturing with Si-P-Sn-Sb alloying
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Solution Overview
Problem
Conventional methods struggle to produce non-oriented electrical steel sheets with high magnetic flux density and low iron loss at a low cost, often resulting in sheet breakage, reduced yield, and increased manufacturing costs due to limitations in Si content and other elements.
Innovation Solution
A manufacturing method involving continuous annealing with hot band annealing and single cold rolling, incorporating a composition with Si > 3.0%, reduced Mn and Al content, added Sn, Sb, and P, along with Ca to control cooling rates and surface temperatures, to enhance magnetic flux density and prevent sheet breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Si content is increased to reduce eddy current loss, then iron loss is reduced, but magnetic flux density decreases
Solution Approach 1:
The patent optimizes the Si content parameter to a specific range (3.0-5.0%) and combines it with controlled amounts of P (0.05-0.20%), Sn (0.01-0.10%), and Sb (0.01-0.10%) to achieve a balance between reducing eddy current loss and maintaining magnetic flux density. This parameter optimization resolves the contradiction by finding the optimal composition point.
Solution Approach 2:
The patent creates a composite alloy system combining Si, P, Sn, and Sb elements in specific proportions. This composite approach allows the material to simultaneously achieve low eddy current loss (through high Si) and high magnetic flux density (through the synergistic effects of P, Sn, and Sb additions).
2Reliability
If P content is increased to improve magnetic flux density, then magnetic flux density increases, but sheet breakage occurs during rolling
Solution Approach 1:
The patent limits P content to a specific range (0.05-0.20%) rather than using high amounts. This controlled parameter change prevents excessive embrittlement while still achieving the desired magnetic flux density improvement, thus resolving the contradiction between magnetic properties and rollability.
Solution Approach 2:
The patent combines P with small amounts of Sn (0.01-0.10%) and Sb (0.01-0.10%) to create a localized compositional optimization. This allows the P to provide magnetic flux density enhancement while the Sn and Sb help maintain ductility and prevent sheet breakage during rolling.
3Reliability
If Al content is reduced to improve magnetic flux density, then magnetic flux density improves, but manufacturing complexity increases
Solution Approach 1:
The patent sets Al content to a specific low range (0.017-0.050%) and compensates by optimizing other alloying elements (P, Sn, Sb). This parameter change achieves high magnetic flux density while maintaining compatibility with conventional manufacturing processes, avoiding the need for complex warm rolling or multiple cold rolling passes.
4Reliability
If Sn and Sb are added to improve magnetic flux density, then magnetic flux density increases, but manufacturing cost increases
Solution Approach 1:
The patent limits Sn and Sb content to small amounts (0.01-0.10% each) rather than using large quantities. This controlled parameter change provides the necessary magnetic flux density enhancement while keeping the cost increase minimal, resolving the contradiction between performance improvement and manufacturing cost.
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 method stabilizes the production of non-oriented electrical steel sheets with excellent magnetic flux density and iron loss properties at a lower cost, reducing sheet breakage and manufacturing costs while maintaining productivity.
Implementation Method 1
subjecting the slab to heating, then subjecting the slab to hot rolling
Implementation Method 2
subjecting the steel sheet to hot band annealing
Implementation Method 3
subjecting the slab to hot rolling to obtain a hot rolled steel sheet
Implementation Method 4
subjecting the steel sheet to subsequent single cold rolling to obtain a final sheet thickness
Implementation Method 5
subjecting the steel sheet to final annealing
Data Source
AI summary
Provided is a method for stably obtaining a non-oriented electrical steel sheet with high magnetic flux density and excellent productivity, at a low cost by casting in a continuous casting machine a slab having a chemical composition including by mass %, C≦0.0050%, 3.0%<Si≦5.0%, Mn≦0.10%, Al≦0.0010%, 0.040%<P≦0.2%, N≦0.0040%, 0.0003%≦S≦0.0050%, Ca≦0.0015%, and total of at least one element selected from Sn and Sb: 0.01% or more and 0.1% or less, balance including Fe and incidental impurities, subjecting the slab to heating, then subjecting the slab to hot rolling to obtain a hot rolled steel sheet, then subjecting the steel sheet to hot band annealing, pickling, subsequent single cold rolling to obtain a final sheet thickness, then subjecting the steel sheet to final annealing, wherein in the hot band annealing, soaking temperature is 900° C. or higher and 1050° C. or lower, and cooling rate after soaking is 5° C/s or more.