Grain-Oriented Electrical Steel Microalloying for Low-Heating Rollability
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Solution Overview
Problem
Existing methods for producing grain-oriented electrical steel sheets via thick slab casting face challenges in achieving both improved cold-rollability and magnetic properties due to heterogeneous microstructures and the need for additional process steps, particularly when using the Low Heating technology.
Innovation Solution
A method involving a carefully balanced composition of Mo, V, Nb, and Ti, along with Cu, in the steel slab, combined with optimized process conditions, to form carbonitrides and nitrides as additional inhibitor particles, improving the hot strip microstructure and magnetic properties without requiring additional production steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If Low Heating technology is used to produce grain-oriented electrical steel sheet via thick slab casting, then energy consumption is reduced and manufacturing cost decreases, but the microstructure becomes heterogeneous and cold-rollability deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the steel slab by adding specific microalloying elements (V, Nb, Ti, Mo) in controlled amounts. This compositional modification enables the formation of fine inhibitor particles during low-temperature processing, which in turn improves microstructure homogeneity and cold-rollability without requiring high energy input
Solution Approach 2:
The invention creates a composite inhibition system by combining multiple microalloying elements (V, Nb, Ti, Mo) that form different types of inhibitor particles (carbonitrides, carbides, nitrides). This composite approach at the microstructural level achieves homogeneous grain refinement and improved cold-rollability under low-heating conditions
2Reliability
If additional process steps are introduced to improve microstructure homogeneity and cold-rollability, then magnetic properties improve, but manufacturing complexity and production time increase
Solution Approach 1:
The invention performs preliminary action by incorporating the necessary microalloying elements (V, Nb, Ti, Mo) into the steel slab composition before casting. These elements pre-form inhibitor particles during solidification and subsequent low-temperature processing, eliminating the need for additional post-processing steps to achieve homogeneous microstructure and good cold-rollability
Solution Approach 2:
The microalloying elements added to the steel slab automatically form fine inhibitor particles during the normal low-temperature processing sequence. This self-service mechanism generates the necessary microstructural homogeneity and cold-rollability improvement without requiring external intervention or additional process steps
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 achieves improved cold-rollability and excellent magnetic properties in the final grain-oriented electrical steel sheet, reducing strip breakages and enhancing magnetic performance, while maintaining a homogeneous microstructure.
Implementation Method 1
form carbonitrides and nitrides as additional inhibitor particles
Implementation Method 2
form carbonitrides and nitrides as additional inhibitor particles
Implementation Method 3
Annealing the hot strip
Implementation Method 4
Decarburization annealing of the cold strip
Implementation Method 5
nitriding annealing during or after decarburization annealing
Data Source
AI summary
A grain-oriented electrical steel sheet includes, in wt. %: Si: 2.0 to 4.0, Mn: 0.01 to 0.5, C: up to 0.005, Alsl: up to 0.0030, N: up to 0.005, S: up to 0.002, the sum of C and N is ≤0.0065 wt. %, at least one element selected from the group consisting of V, Nb, Ti, Mo with the following contents, in wt. %, V: 0.0005 to 0.0060, Nb: 0.0005 to 0.0060, Ti: 0.0005 to 0.0030, Mo: 0.0005 to 0.03; in case the content of Mo is >0.010 wt. %, the sum of the contents of V, Nb, Ti and Mo is ≤0.040 wt. % and Cu is present in an amount of 0.02 to 0.6 wt. % and in case the content of Mo is ≤0.010% the sum of the contents of V, Nb, Ti and Mo is ≤0.030 wt. % and Cu is optionally present in an amount of 0.002 to 0.6 wt. %.