NON-ORIENTED ELECTRICAL STEEL
Non-oriented silicon steel is a silicon-iron alloy with very low carbon content. The grains in the steel plate after deformation and annealing are randomly oriented.
The silicon content of its alloy is usually 1.5% – 3.0%, or the sum of silicon and aluminum content is 1.8% – 4.0%. The products are generally cold-rolled sheets or strips with a nominal thickness of 0.35 and 0.5 mm. It is mainly used in the manufacture of motors and generators, and therefore is also known as cold-rolled motor silicon steel.
The contents of elements such as silicon, aluminum and manganese in the steel need to be controlled within a certain range as required, and the impurity contents such as carbon, sulfur, nitrogen and oxygen should be as low as possible. With the increase of the grade, the silicon content can be increased to about 3% and remains unchanged, and the aluminum content can be gradually increased to 1%. The aluminum content of general grades is 0.3% – 0.6%. At the same time, the contents of carbon, sulfur and manganese in high-grade grades will be further reduced. For example, the impurity content requirements for high grades are: S < 0.002%, C < 0.003%, N₂ < 0.002%, O₂ < 0.002%, so that decarbonization is not required during subsequent annealing to prevent the formation of internal oxide and nitride layers. In addition, it is usually also required that Ti < 0.005% and Zr < 0.002% to avoid the formation of fine TiN, ZrN and TiC that hinder grain growth.
Process Flow
Non-oriented silicon steel has the following performance index characteristics:
Low iron loss: This is an important indicator of quality. Countries around the world usually classify grades based on iron loss values. The lower the iron loss, the higher the grade and the better the quality.
High magnetic induction intensity: Silicon steel sheets that can obtain higher magnetic induction under the same magnetic field. The volume and weight of the motor or transformer core manufactured with it are smaller, and relatively, silicon steel sheets, copper wires and insulating materials can be saved.
High stacking factor: The surface of the silicon steel sheet is smooth, flat and uniform in thickness, which can increase the stacking factor for manufacturing the core.
Good punching property: This is particularly important for manufacturing small and micro motor cores.
Good adhesion and weldability of the surface to the insulating film: It can play a role in preventing corrosion and improving the punching property.
Low magnetic aging phenomenon.
Market Demand
With the transformation of the global energy structure, the electrification trend and the promotion of the national dual-carbon strategy, the demand for energy-saving products and raw materials is growing rapidly. The net growth high-grade market represented by new energy vehicles and the structure-optimized high-grade market represented by IE5 motors, new hydropower and high-energy-efficiency household appliances have considerable increments. It is expected that the overall demand for non-oriented silicon steel in 2025 will increase by approximately 8.6% based on 2022. For example, in the new energy vehicle industry, a rapid development period will be ushered in in the next 3 years, which is the main incremental market for high-grade non-oriented silicon steel; in the household appliance industry, affected by frequency conversion and miniaturization, although the overall demand for silicon steel in compressors shows a downward trend, the demand for high grades increases year by year; in the industrial motor field, high-grade non-oriented silicon steel used in IE4/5 ultra-efficient motors is an important functional material for reducing carbon emissions in the industrial field and achieving the goals of carbon peak and carbon neutrality; in the field of power generation equipment, all large-scale power generation requires the use of high-grade non-oriented silicon steel.
In conclusion, as an important metal functional material, non-oriented silicon steel plays a key role in fields such as power, electronics and military industry, and is of great significance for improving energy utilization efficiency and reducing equipment operating costs. The continuous improvement of its performance and quality will also further promote the development and progress of related industries.
I. Aspects of Difference Between Grain-oriented silicon and Non-oriented
Magnetism:Grain-oriented silicon steel has high magnetic permeability and low iron loss along a specific direction, with strong directionality.
Non-oriented silicon steel has relatively uniform magnetism in all directions, and its magnetic performance is slightly poorer.
Usage:Grain-oriented silicon steel is used in transformers because of its excellent magnetic performance in a specific direction, which can improve energy efficiency and reduce volume.
Non-oriented silicon steel is used in motors. The magnetic field of the motor is complex, and the requirement for the magnetic direction is low.
Manufacturing process:The manufacturing process of grain-oriented silicon steel is complex, requiring high-temperature annealing and special coatings to achieve good orientation.
The process of non-oriented silicon steel is relatively simple.
Price:Grain-oriented silicon steel has excellent performance and a complex process, and the price is high.
II. Illustrative Examples
Take large power transformers as an example. To ensure efficient energy transmission and reduce volume, grain-oriented silicon steel is often selected. In industrial motors, due to the complex magnetic field, non-oriented silicon steel is more applicable and has a lower cost.
III. Conclusion
Non-oriented silicon steel and grain-oriented silicon steel have significant differences in magnetism, usage, manufacturing process and price. Users choose based on the application scenarios and performance requirements.
