Non-oriented electrical steel sheet for high-speed rotating machines
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Solution Overview
Problem
Non-oriented electrical steel sheets for high-speed rotating machines face a challenge in simultaneously achieving high tensile strength and low high-frequency iron loss, as existing techniques are complex, costly, and difficult to manufacture.
Innovation Solution
A non-oriented electrical steel sheet with specific chemical compositions and microstructural adjustments, including Si, Mn, Ni, P, and Nb content, and grain refinement, to balance tensile strength and high-frequency iron loss, facilitating simpler manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-Si-content hot rolled steel sheet is obtained with various temperature controls to achieve high tensile strength, then tensile strength is improved, but manufacturing complexity and costs increase due to specialized temperature controls and cold rolling difficulties
Solution Approach 1:
The invention changes the chemical composition parameters by limiting Si content to 2.0-3.5 mass% (reducing from high-Si content) and introducing specific ranges for Al (0.05-2.0 mass%), P (0.005-0.1 mass%), and total Ni+Mn (0.03-1.5 mass%). These parameter changes enable high tensile strength while avoiding the manufacturing complexities associated with high-Si steel, as the optimized composition allows standard cold rolling and heat treatment processes to achieve the desired mechanical properties without specialized temperature controls
2Strength
If high-Si-content steel sheet is produced to achieve high tensile strength, then tensile strength is improved, but cold rolling becomes difficult due to embrittlement
Solution Approach 1:
The invention optimizes the chemical composition by limiting Si to 2.0-3.5 mass% (avoiding high-Si embrittlement) and carefully controlling Al (0.05-2.0 mass%), P (0.005-0.1 mass%), and total Ni+Mn (0.03-1.5 mass%). This balanced composition provides sufficient solid solution strengthening for high tensile strength while maintaining adequate ductility and cold formability, allowing standard cold rolling processes to be used without specialized handling or reduced rolling ratios
3Strength
If various temperature controls are implemented to enable cold rolling of high-Si steel, then tensile strength is achieved, but time, labor and costs are pushed up
Solution Approach 1:
The invention adopts a balanced chemical composition with Si: 2.0-3.5 mass%, Al: 0.05-2.0 mass%, P: 0.005-0.1 mass%, and total Ni+Mn: 0.03-1.5 mass%, which provides adequate solid solution strengthening without requiring complex temperature control schedules. This composition allows conventional hot rolling followed by standard cold rolling and annealing processes to achieve the required tensile strength, significantly reducing manufacturing time, labor, and costs compared to specialized multi-stage temperature control processes
Solution Approach 2:
The invention extracts and eliminates the need for specialized temperature control processes by adopting an optimized chemical composition that achieves high tensile strength through standard metallurgical processes. By removing the requirement for complex heat treatment schedules and specialized rolling temperature controls, the invention simplifies the manufacturing workflow and reduces process time while maintaining the desired mechanical properties
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 yield strength and low high-frequency iron loss while simplifying the manufacturing process, avoiding complications like embrittlement and processing difficulties.
Implementation Method 1
by way of solid solution strengthening, precipitation strengthening, work strengthening, grain refinement strengthening, and strengthening by phase-transformed structure
Implementation Method 2
by way of solid solution strengthening, precipitation strengthening, work strengthening, grain refinement strengthening, and strengthening by phase-transformed structure
Implementation Method 3
by way of solid solution strengthening, precipitation strengthening, work strengthening, grain refinement strengthening, and strengthening by phase-transformed structure
Implementation Method 4
by way of solid solution strengthening, precipitation strengthening, work strengthening, grain refinement strengthening, and strengthening by phase-transformed structure
Data Source
Figure 1
AI summary
A non-oriented electrical steel sheet contains 2.8 mass% or more and 4.0 mass% or less of Si, 0.2 mass% or more and 3.0 mass% or less of Al, and 0.02 mass% or more and 0.2 mass% or less of P. The non-oriented electrical steel sheet contains further contains 0.5 mass% or more in total of at least one kinds selected from a group consisting of 4.0 mass% or less of Ni and 2.0 mass% or less of Mn. A C content is 0.05 mass% or less, a N content is 0.01 mass% or less, an average grain diameter is 15 µm or less, and a <111> axial density is 6 or larger.