POSCO has broken ground for another electrical steel plant. South Korea’s top steelmaker will spend 1 trillion won (US$805 million) in building the plant in the southwestern port of Gwangyang, which will have an annual production capacity of 300,000 tons of non-oriented electrical steel.
Electrical steels (earlier post) are special steels optimized for specific magnetic properties, including a small hysteresis area for low power loss per cycle, low core loss and high permeability. Electrical steels are found throughout a modern vehicle—from the small motors which drive mirrors and seats to the larger machines that are used in the propulsion systems of hybrid or full EVs. Traction motors and generators in those alternative drive trains are particularly dependent on highly efficient electrical steels.
The commercial electrical steel market is divided in two major categories: the grain-oriented electrical steel (GOES) market and the non-oriented electrical steel (NOES) market. GOES is used in static machinery such as transformers, which require unidirectional magnetization, while NOES is used in rotating machinery such as motors and generators, which require multidirectional magnetization.
NOES is a direct material input used in electric motor manufacturing for both hybrid and electric vehicles.
Steps in the production of non-oriented electrical steel include:
Preliminary Annealing. In this process, scales on the surface of the hot-rolled coil are removed by scale breaker and hydrochloric acid cleaning. This process improves cold rolling properties of steel as well as its magnetic properties.
Cold Rolling. To obtain specific thickness and material properties, POSCO uses a cold rolling process. For uniform thickness and width of strip, this process is controlled automatically.
Annealing. Annealing is a recrystallizing process of hardened cold-rolled structures by heat treatment. There are two annealing processes for grain-oriented electrical steel: decarbonization and high temperature annealing. During decarbonization annealing, excess carbon in the steel is removed and a MgO coating is applied on the surface of the steel. High-temperature annealing produces secondary recrystallized structures having superior magnetic properties. Non grain-oriented electrical steel is recrystallized and insulation coating is applied during the annealing process.
Insulation Coating. In this process, insulation coating is applied continuously to minimize eddy current losses, which are proportional to the sheet thickness. Grain-oriented electrical steel has two layers of coating; one is base coating with dark brown color which consists of Forsterite(Mg2SiO4), and the other is transparent insulation coating containing phosphates. For non grain-oriented electrical steel, there are various types of coatings according to final usage and customer’s requests.
The new NOES plant in Gwangyang will boost Posco’s capacity to produce NOES to 400,000 tons annually from its current 100,000 tons. POSCO currently produces more than 1 million tons of both types of electrical steel every year.
According to market tracker IHS Markit, demand for non-oriented electrical steel from automakers will rise at an annualized rate of 20% to 4 million tons in 2033, from 320,000 tons in 2020.
POSCO’s existing integrated steel mill in Gwangyang is the largest in the world. The company reportedly will invest 5 trillion won (US$4.1 billion) in Gwangyang over the next three years.