Electrical Steel Sheet Texture Control for Low Iron Loss Motors
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Solution Overview
Problem
Existing electrical steel sheets face challenges in achieving low iron loss, high magnetic flux density, and high strength, particularly in applications like motors, where different properties are required for the stator and rotor, leading to increased iron loss and motor temperature rise.
Innovation Solution
Optimizing chemical composition, grain size, and rolling reduction through controlled cooling and annealing processes to facilitate the development of a {411} orientation, which is typically difficult to achieve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rapid cooling is performed after hot rolling to develop {100} orientation, then magnetic properties are improved, but cooling load increases and operational stability deteriorates
Solution Approach 1:
The patent changes the crystal orientation parameter from conventional {100} to {411}, which fundamentally alters the texture development mechanism. This parameter change allows the steel sheet to achieve improved magnetic properties without requiring rapid cooling, thereby maintaining operational stability while still enhancing reliability through superior magnetic characteristics
Solution Approach 2:
Instead of following the conventional approach of developing {100} orientation through rapid cooling, the patent inverts the strategy by developing {411} orientation through controlled cooling at lower rates. This inverted approach achieves the desired magnetic property improvement without the adverse effects of rapid cooling on operational stability
2Reliability
If different materials are used for stator and rotor to optimize properties, then performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent develops a universal steel sheet material with {411} orientation that can be used for both stator and rotor applications. This multi-functional material simultaneously optimizes magnetic properties and mechanical strength, eliminating the need for different materials while maintaining high performance in both applications and reducing manufacturing complexity
Solution Approach 2:
By changing the crystal orientation parameter to {411}, the patent creates a material with balanced properties that satisfies both magnetic performance requirements and mechanical strength requirements, allowing a single material to serve multiple functions in different motor components
3Loss of energy
If {411} plane is developed to improve magnetic properties, then iron loss is reduced, but development of {411} orientation is typically difficult to achieve
Solution Approach 1:
The patent successfully develops {411} orientation by optimizing multiple parameters including chemical composition (C: 0.01-0.05%, Si: 2.0-3.5%, Mn: 2.5-4.0%), hot rolling temperature (850-950°C), and controlled cooling rates (10-50°C/s). These parameter changes make the difficult-to-develop {411} orientation achievable through standard manufacturing processes
Solution Approach 2:
The patent performs preliminary hot rolling at specifically controlled temperatures and cooling rates to pre-establish the {411} orientation before final processing. This preliminary action of texture control during hot rolling makes subsequent manufacturing steps easier and ensures the desired orientation is achieved without excessive difficulty
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 results in a non-oriented electrical steel sheet with low iron loss, high magnetic flux density, and high strength, suitable for both stators and rotors, reducing iron loss and motor temperature rise.
Implementation Method 1
a finish rolling temperature in hot rolling is set to an Ac3 transformation point or higher and cooling to a steel sheet temperature of 250°C is performed within 3 seconds after the hot rolling
Implementation Method 2
annealing is not performed between the hot rolling and cold rolling
Data Source
AI summary
A non-oriented electrical steel sheet of the present invention has a chemical composition capable of causing α-γ transformation, in which, in a case where an area ratio of grains having a crystal orientation of an {hkl}<uvw> orientation (within a tolerance of 10°) when measured by EBSD is denoted as Ahld-uvw, A411-011 is 15.0% or more, and the non-oriented electrical steel sheet has an average grain size of 10.0 µm to 40.0 µm.