Non-oriented electrical steel sheet P segregation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing non-oriented electrical steel sheets with high magnetic flux density face challenges such as increased production costs and decreased productivity, while also compromising on motor torque and copper loss due to high Si or Al content.
Innovation Solution
A non-oriented electrical steel sheet with a specific chemical composition, including controlled amounts of P, Al, C, B, and Se, and additional elements like Sn, Sb, REM, Mg, and Ca, is produced through a process involving hot rolling, hot band annealing, cold rolling, and finish annealing, which promotes P segregation at grain boundaries, enhancing magnetic properties without significant cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a large amount of Si or Al is added to increase electric resistance, then eddy current loss is decreased, but magnetic flux density is decreased
Solution Approach 1:
The invention changes the chemical composition parameters by strictly limiting Si to 1.0-5.0 mass% and Al to 0.003-0.030 mass%, while adding P (0.005-0.050 mass%) and controlling impurities (C, B, Se) to enable P segregation. This parameter optimization resolves the contradiction by achieving low eddy current loss through controlled Si addition while maintaining high magnetic flux density through P segregation and low impurity content.
Solution Approach 2:
The invention creates a composite microstructure through P segregation at grain boundaries, combining the benefits of Si for electrical resistance with P for texture control. The segregated P forms a composite system where P-rich grain boundaries and P-poor matrix regions work together to achieve both low iron loss and high magnetic flux density, resolving the contradiction between these two properties.
2Quantity of substance
If batch annealing at low temperature for long time is conducted to improve texture, then magnetic flux density is increased, but productivity is decreased and production cost is increased
Solution Approach 1:
The invention performs preliminary action by adding P during steelmaking and controlling the chemical composition before rolling. This preliminary P addition and composition control enable spontaneous P segregation during standard hot band annealing, eliminating the need for subsequent long-time low-temperature batch annealing. The preliminary compositional design achieves high magnetic flux density while maintaining high productivity.
Solution Approach 2:
The invention skips the conventional long-time low-temperature batch annealing step by using standard hot band annealing conditions (800-1200°C for seconds to minutes). The P segregation and texture development occur rapidly during this skipped step, achieving the same or better magnetic properties without the time-consuming batch annealing process, thus resolving the productivity contradiction.
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 stably produces steel sheets with high magnetic flux density while maintaining low production costs, improving texture and reducing iron loss, thus suitable for motor cores with enhanced magnetic properties.
Implementation Method 1
promotes P segregation at grain boundaries, enhancing magnetic properties
Implementation Method 2
conducting a batch annealing at a low temperature for a long time before cold rolling
Implementation Method 3
The method of producing a non-oriented electrical steel sheet comprises a series of steps of hot rolling, conducting a hot band annealing, performing one cold rolling or two or more cold rollings interposing an intermediate annealing therebetween
Data Source
AI summary
A non-oriented electrical steel sheet is obtained by subjecting a slab containing C: not more than 0.005 mass %, Si: 1.0-5.0 mass %, Mn: 0.04-3.0 mass %, sol. Al: not more than 0.005 mass %, P: 0.03-0.2 mass %, S: not more than 0.005 mass %, N: not more than 0.005 mass %, B: not more than 0.001 mass %, and Se: not more than 0.001 mass % and satisfying sol. Al+C+5B+5Se≤0.005 mass % to hot rolling, cold rolling and finish annealing. A sheet temperature at the outlet side of the rolling machine in at least one pass of the final cold rolling is set to a range of 100-300° C. to provide S/2M of not less than 1.0 and S/5C of not less than 1.0 when X-ray intensity ratios of {001}<250>, {111}<112> and {001}<100> in a central layer in a thickness direction are S, M and C, respectively.