Grain Oriented Magnetic Strip Production Process
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Solution Overview
Problem
Traditional processes for producing grain-oriented magnetic steel face challenges such as high energy consumption, maintenance issues, and quality fluctuations due to the need for precise control of second phase precipitation during hot-rolling and annealing, which affects the magnetic characteristics and brittleness of the final product.
Innovation Solution
A process involving continuous casting of silicon steel with specific elemental compositions and controlled thermal and mechanical treatments to achieve a distribution of second phases capable of controlling secondary recrystallization, eliminating the need for pre-heating slabs and optimizing the formation of second phases during hot-rolling, thereby improving magnetic characteristics and reducing production complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If slabs are heated to very high temperatures (>1300°C) before hot-rolling to dissolve second phases, then the second phases can re-precipitate during hot-rolling and annealing to control secondary recrystallization, but this causes remarkable power consumption, maintenance problems from liquid slag formation, and surface injuries to the slab
Solution Approach 1:
The invention changes the temperature parameter from very high temperatures (>1300°C) to intermediate temperatures (900-1150°C) for slab heating before hot-rolling. This parameter change allows sufficient dissolution of second phases without causing liquid slag formation or excessive power consumption, while still enabling controlled re-precipitation during subsequent hot-rolling and annealing operations.
Solution Approach 2:
The invention performs preliminary dissolution of second phases during slab heating at intermediate temperatures before hot-rolling. This preliminary action prepares the microstructure for controlled re-precipitation during hot-rolling and annealing, achieving the desired control of secondary recrystallization without requiring extremely high temperatures.
2Reliability
If slabs are heated to very high temperatures (>1300°C) before hot-rolling to dissolve second phases, then controlled precipitation occurs during hot-rolling and annealing, but this creates maintenance problems due to liquid slag formation and kneading with moving mechanisms
Solution Approach 1:
The invention changes the heating temperature parameter from very high temperatures (>1300°C) to intermediate temperatures (900-1150°C). This parameter change prevents the formation of liquid slag while still allowing sufficient dissolution of second phases for controlled re-precipitation during hot-rolling and annealing, thereby eliminating maintenance problems associated with liquid slag kneading.
3Reliability
If slabs are heated to very high temperatures (>1300°C) before hot-rolling to dissolve second phases, then the second phases can control secondary recrystallization, but the slab surface is subjected to injuries that appear on the final product
Solution Approach 1:
The invention changes the slab heating temperature from very high temperatures (>1300°C) to intermediate temperatures (900-1150°C). This parameter change eliminates surface injuries caused by excessive thermal stress and oxidation while still providing sufficient dissolution of second phases for controlled re-precipitation during hot-rolling and annealing, thereby maintaining surface quality.
4Reliability
If the content of elements capable of forming second phases is strictly controlled to achieve proper dissolution and re-precipitation, then secondary recrystallization can be controlled, but this increases process complexity and makes strict control difficult due to fluctuations in chemical activities
Solution Approach 1:
The invention changes the approach from strict control of element concentrations and chemical activities to control of temperature parameters and process timing. By using intermediate temperatures (900-1150°C) and controlling the sequence of operations (heating before hot-rolling, then hot-rolling, then annealing), the process achieves reliable control of secondary recrystallization without requiring extremely precise control of alloying elements.
Solution Approach 2:
The invention replaces the complex chemical control system (monitoring and adjusting element concentrations, chemical activities, and solubility products) with a more manageable thermal process control system (controlling temperatures and holding times). This substitution simplifies the control mechanism while maintaining reliable control of secondary recrystallization.
5Reliability
If second phases are completely dissolved during slab heating before hot-rolling, then they can re-precipitate during hot-rolling and annealing, but this requires temperatures higher than necessary and increases energy consumption
Solution Approach 1:
The invention changes the dissolution temperature parameter from very high temperatures (>1300°C) to intermediate temperatures (900-1150°C). This parameter change provides sufficient dissolution of second phases for controlled re-precipitation during hot-rolling and annealing, while significantly reducing energy consumption compared to traditional very high temperature heating.
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 process enhances the magnetic properties of grain-oriented silicon steel, increases the silicon content beyond traditional limits, and stabilizes the microstructure, leading to improved dimensional stability and reduced power consumption.
Implementation Method 1
An important role in the production process is played by the precipitation of second phases, typically sulphides and/or selenides and/or nitrides, finely distributed into the matrix, determinant for controlling the grain growth during the secondary recrystallization process.
Implementation Method 2
the slab before hot-rolling is subjected to a heating treatment at temperatures intermediate between the temperatures required to obtain the dissolution of a significant amount of second phases and those required to prevent their dissolution
Implementation Method 3
secondary recrystallization annealing of the strip
Data Source
AI summary
A process for the production of a grain oriented magnetic strip, made of steel containing 2.3 to 5.0% of silicon, obtained by producing a hot-rolled sheet containing a distribution of second phases capable of controlling the secondary recrystallization by means of a two-step hot-rolling with an intermediate annealing, and by changing it into the final product.