Non-oriented electrical steel sheet composition for core loss reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The production of high-quality non-oriented electrical steel sheets is hindered by difficulties in controlling impurities like C, S, N, Ti, and fine inclusions, which affect magnetic properties and increase core loss, making it challenging to achieve optimal magnetic flux density and processability.
Innovation Solution
Optimizing the proportions of Al, Si, Mn, N, and S in the steel composition to increase the distribution density of coarse inclusions, thereby enhancing grain growth and domain wall mobility, while maintaining low hardness, through specific heat treatment and rolling processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the amount of Si is increased to reduce core loss, then magnetic properties are improved, but magnetic flux density decreases and processability deteriorates
Solution Approach 1:
The patent optimizes the composition parameters by limiting Si to 0.5-2.5 wt% and introducing Al (1.0-3.0 wt%) and Mn (0.5-2.0 wt%) as alternative alloying elements. This parameter change maintains energy loss reduction while improving processability and magnetic flux density through different mechanisms.
Solution Approach 2:
The patent creates a composite alloying system combining Al, Si, and Mn in specific proportions. This composite approach leverages the complementary strengths of each element: Al for grain growth and softness, Si for core loss reduction, and Mn for magnetic property enhancement, achieving a balance that single-element alloying cannot provide.
2Manufacturing precision
If impurities including C, S, N, Ti are controlled to minimum to increase grain growth, then magnetic properties are improved, but the cost of steel making process increases
Solution Approach 1:
The patent sets specific impurity parameter ranges (C: 0.004% or less, S: 0.0005-0.004%, N: 0.001-0.004%) that are lenient enough for conventional steelmaking while still achieving sufficient grain growth. This parameter optimization reduces production cost by avoiding excessive purification requirements.
Solution Approach 2:
The patent uses Al-N and Al-S inclusions as substitutes for traditional fine inclusions like MnS and TiN. These Al-based inclusions form more readily in conventional steelmaking processes and provide similar or superior grain growth promotion effects, reducing the need for costly impurity control measures.
3Stability of the object's composition
If fine inclusions such as MnS and AlN are present in steel, then steel structure is formed, but grain growth is hindered and hysteresis loss increases
Solution Approach 1:
The patent converts the typically harmful effect of inclusions on grain growth into a beneficial effect by using Al-N and Al-S inclusions. These inclusions, while present in the steel structure, provide grain growth promotion effects similar to fine inclusions but without the harmful hysteresis loss increase, effectively turning a potential problem into a solution.
Solution Approach 2:
The patent changes the composition parameters by increasing Al content (1.0-3.0 wt%) relative to traditional formulations. This parameter change shifts the inclusion chemistry from MnS/AlN to Al-rich nitrides and sulfides, which have different properties that promote grain growth while maintaining steel structure stability and avoiding hysteresis loss increase.
4Manufacturing precision
If Al and Mn are increased to improve magnetic properties, then magnetic flux density increases, but the formation of coarse inclusions may decrease
Solution Approach 1:
The patent optimizes the interaction parameters between Al, Mn, N, and S by setting specific composition ranges. This parameter optimization ensures that Al and Mn work synergistically to promote both coarse inclusion formation and grain growth, rather than competing effects. The balanced composition allows magnetic property enhancement and inclusion formation to occur simultaneously.
Solution Approach 2:
The patent creates a composite inclusion system where Al-N and Al-S inclusions work together with Al-rich phases. This composite inclusion structure provides multiple benefits: promoting grain growth through appropriate size and distribution, maintaining magnetic flux density through controlled composition, and ensuring mechanical properties through balanced inclusion characteristics.
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 non-oriented electrical steel sheets with superior magnetic properties, improved productivity, and reduced production costs by stabilizing the formation of coarse inclusions and minimizing fine inclusions, thus enhancing magnetic flux density and core loss performance.
Implementation Method 1
an inclusion comprising a nitride and a sulfide alone or a combination thereof is formed in the steel sheet
Implementation Method 2
cold rolling, and final annealing at 750 ∼ 1100°C
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to a non-oriented electrical steel sheet. Provided are: a non-oriented electrical steel sheet having outstanding magnetic properties and comprising, as percentages by weight, from 1.0 to 3.0% of Al, from 0.5 to 2.5% of Si, from 0.5 to 2.0% of Mn, from 0.001 to 0.004% of N, from 0.0005 to 0.004% of S and a balance of Fe and other unavoidably incorporated impurities, wherein the Al, Mn, N and S are included so as to satisfy the compositional formulae {[Al]+[Mn]}≤3.5, 0.002≤{[N]+[S]}≤0.006, 300≤{([Al]+[Mn])/([N]+[S])}≤1,400; and a production method therefor. By optimising the Al, Si, Mn, N and S added components in this way, the distribution density of coarse inclusions is increased, thereby making it possible to improve crystal-grain growth properties and domain wall motility and so produce the highest grade of non-oriented electrical steel sheet having superior magnetic properties, low hardness, and superior customer workability and productivity.