A Comprehensive Analysis of Grain-Oriented Silicon Steel Coil: The Preferred Core Material for Transformers

A Comprehensive Analysis of Grain-Oriented Silicon Steel Coil: The Preferred Core Material for Transformers

In the field of power transmission and conversion, the key to transformer performance lies in its core material—grain-oriented silicon steel coil. This seemingly ordinary alloy is a hidden champion in the modern power industry.

As an important soft magnetic alloy, grain-oriented silicon steel coil is an indispensable functional material in the power, electronics, and military industries, primarily used as the core of various transformers, generators, and transformers.

Due to its complex production process and rigorous manufacturing techniques, domestic and foreign manufacturers protect their production technology through patents, viewing it as the lifeblood of their business. This article will comprehensively analyze the specifications, magnetic properties, and major manufacturers of grain-oriented silicon steel coil for transformers.

01 What is Grain-Oriented Silicon Steel Coil?
Grain-oriented silicon steel coil is a ferrosilicon alloy with a silicon content of approximately 3% to 5%, with iron as the remaining major component. Compared to non-grain-oriented silicon steel, its magnetic properties exhibit a strong directional nature—superior high permeability and low loss in the rolling direction, which favors magnetization.

This material's iron loss in the rolling direction is only one-third of that in the transverse direction, and its magnetic permeability ratio is 6:1. Its iron loss is approximately half that of hot-rolled strip, and its magnetic permeability is approximately 2.5 times that of the latter.

02 Key Magnetic Performance Parameters of Grain-Oriented Silicon Steel
The performance requirements for silicon steel mainly include the following aspects:

Iron loss (core loss): This is the most important indicator of silicon steel sheet quality. Countries classify grades based on iron loss values; the lower the iron loss, the higher the grade. For example, the iron loss (P1.7/50) of 30QG120 grain-oriented silicon steel can be ≤1.1W/kg.

Magnetic induction intensity (magnetic induction): High magnetic induction intensity in strong magnetic fields can reduce the size and weight of the core in motors and transformers, saving silicon steel sheets, copper wire, and insulation materials. The B value of high-magnetic induction grain-oriented silicon steel can reach 1.88T-1.89T.

Surface quality: A smooth, flat surface with uniform thickness can improve the core's fill factor.

Punching Performance: Good punching performance is particularly important for the manufacture of micro and small motors.

Surface Insulation Film: Excellent adhesion and weldability provide corrosion protection and improve punching performance.

03 Detailed Specifications of Mainstream Manufacturers' Products
Baosteel Grain-Oriented Silicon Steel Product Series
Baosteel's grain-oriented silicon steel is divided into three main series:

G-General Series: Includes B23G110, B23G120, B27G110, B27G120, B27G130, B30G120, B30G130, B30G140, B35G135, B35G145, and B35G155. These products have a theoretical density of 7.65 kg/dm³ and a minimum magnetic induction of 1.80 T.

P - High Induction Series: Includes B23P085, B23P090, B23P095, B23P100, B27P090, B27P095, B27P100, B30P100, B30P105, B30P110, B30P120, B35P115, B35P125, B35P135, etc. These series have a minimum induction of 1.87T-1.88T.

R - Domain Refined High Induction Series (Laser Scribing): Includes B23R080, B23R085, B23R090, B27R085, B27R090, B27R095, etc., with a minimum induction of 1.87T.

WISCO Grain-Oriented Silicon Steel Product Series
WISCO's grain-oriented silicon steel is also divided into three main series:

Q - General Grain-Oriented Silicon Steel Series: includes 23Q110, 27Q120, 27Q130, 30Q120, 30Q130, 35Q145, 35Q155, etc., with a minimum magnetic induction of 1.80T-1.82T.

QG - High Magnetic Induction Grain-Oriented Silicon Steel Series: includes 23QG090, 23QG095, 23QG100, 27QG095, 27QG100, 27QG120, 30QG105, 30QG120, etc., with a minimum magnetic induction of 1.88T-1.89T.

RK-Domain-Refined High-Magnetic-Induction Grain-Oriented Silicon Steel Series: Includes 23RK080, 23RK085, 23RK090, 23RK095, 27RK085, 27RK090, 27RK095, 27RK100, 27RK120, 30RK100, 30RK105, and 30RK120, with a minimum magnetic induction range of 1.88T-1.89T.

04 Applications and Selection Recommendations
Main Application Scenarios
Grain-oriented silicon steel coils are primarily used in the following areas:

Power Transformer Cores: Used in the manufacture of high-efficiency transformer cores for 500kV and above. Its low iron loss significantly reduces no-load consumption, meeting national energy efficiency standards.

New Energy Power Transformers: Particularly suitable for step-up transformers in renewable energy power generation systems such as wind and photovoltaic power generation. Its high magnetic induction improves energy conversion efficiency.

Core Materials for Industrial Inverters: Serves as the electromagnetic core material for high-power industrial inverters, UPS power supplies, and other equipment.

Selection Recommendations
When selecting oriented silicon steel coils, consider the following factors:

Application Environment: Select the appropriate grade based on the transformer's operating frequency, power level, and operating environment.

Magnetic Performance Requirements: Select materials with corresponding iron loss and magnetic induction values ​​for transformers with different energy efficiency levels.

Cost Considerations: High-performance materials are more expensive, so a balance between performance and cost is required.

Supply Capacity: Select a manufacturer with stable supply capacity to ensure production continuity.

05 Market Price and Supply Situation
The market price of silicon steel coils fluctuates. For example, in May 2025, Shagang lowered the ex-factory price of cold-rolled non-oriented silicon steel coils by 100 yuan/ton compared to the previous month.

During the May Day holiday, the national silicon steel market was largely closed, and silicon steel spot prices generally remained at pre-holiday levels. Prices vary by region and grade:

East China:

Shanghai Market: Baosteel quoted 5,100 yuan/ton, Wuhan Iron & Steel quoted 4,950 yuan/ton, Shougang quoted 4,950 yuan/ton

Hangzhou Market: Baosteel quoted 5,100 yuan/ton, Wuhan Iron & Steel quoted 4,950 yuan/ton, Shougang quoted 4,900 yuan/ton

Ningbo Market: Baosteel quoted 5,130 yuan/ton, Wuhan Iron & Steel quoted 4,950 yuan/ton, Xingang quoted 4,580 yuan/ton

Central China:

Wuhan Market: Wuhan Iron & Steel quoted 4,900 yuan/ton

Loudi Market: Hunan Hongwang quoted 4,400 yuan/ton

North China:

Tianjin Market: Baosteel quoted 5,300 yuan/ton, Wuhan Iron & Steel quoted 5,100 yuan/ton, Shougang quoted 4,700 yuan/ton

South China In the Guangzhou market, Baosteel Zhanjiang reported prices at 4,700 yuan/ton, Wuhan Iron and Steel reported prices at 4,950 yuan/ton, and Angang reported prices at 4,550 yuan/ton.

It should be noted that grain-oriented silicon steel is generally more expensive than non-oriented silicon steel. For example, Baowu Steel's 30QG120 grain-oriented silicon steel costs approximately 10,500 yuan.

06 Major Manufacturers and Direct Supply Information
Major domestic grain-oriented silicon steel coil manufacturers include large steel groups such as Baosteel, Wuhan Iron and Steel, and Shagang.

These manufacturers typically sell their products through a network of first-tier agents and distributors. Companies such as Shanghai Zengyao Industrial Co., Ltd. and Shanghai Minzhong Enterprise Development Co., Ltd. are both important silicon steel coil suppliers in East China.

Many suppliers offer customized services, customizing slits to meet user specifications and offering a variety of coating options (such as A/H/K/Z/T4) to meet the insulation, corrosion resistance, and environmental protection requirements of various applications.

With the rapid development of the new energy industry, especially the widespread adoption of wind and photovoltaic power generation, demand for high-performance grain-oriented silicon steel will continue to grow.

In the future, grain-oriented silicon steel will develop towards lower iron loss, higher magnetic induction strength, and thinner gauges to meet the design requirements of more energy-efficient and smaller transformers.

Selecting the appropriate grain-oriented silicon steel coil not only meets transformer design requirements but also represents a key step in complying with national energy conservation and emission reduction policies.