The POSCO Quality

Electrical steel

Electrical plates are also called electronic plates or silicon plates. Compared to regular steel plates, silicon plates contain more silicon, featuring good electric and magnetic characteristics

Manufacturing Process

Powered by state-of-the-art facility and technology, POSCO operates a totally computerized, end-to-end full automatic production system. This allows us to deliver high-quality and high-performance products to the needs of customers

1. Preliminary Annealing

During the preliminary annealing process, a scale which may have formed on the hot rolled steel is removed as delayed passing through scale breaker and a hydrochloric acid bath. This initial heat treatment process improves the cold rolling properties of steel as well as its magnetic properties.

2. Cold Rolling

In order to obtain specific thickness and material properties, a reduction ratio of 40-90% is applied normally. Rolling and edge trimming machines are automatically controlled to obtain uniform thickness and width.

3. Annealing

Annealing is a process in which cold rolled structures are converted to a recrystallized structure through heat treatment. For grain oriented electrical steel, two different annealing methods are available: decarbonization annealing and high-temperature annealing. Decarbonization annealing removes excess carbon from the steel and applies a MgO coating. High-temperature annealing produces secondary recrystallized structures having superior magnetic properties.

4. Insulation Coating

In this process, insulation coating is applied by a continuous coater roll in order to minimize eddy current losses, which are proportional to the sheet thickness. A series of coaters are used to apply insulation coating liquid to the top and bottom of a plate. Grain oriented electrical steel has two layers of coating, a base coating of dark brown Forsterite (Mg2SiO4) as the main ingredient and a transparent insulating coating containing phosphates. For non-oriented electrical steel, various coating methods with various thicknesses and ingredients are used depending on end usage and specific user’s requirements.

  • 예비소둔
  • 냉간압연
  • 소둔(열처리)
  • 절연코팅