Application of Graphite Electrode Plasma Heating Technology in Continuous Casting.

Area of Science:

• Metallurgical Engineering
• Plasma Physics
• Materials Science

Background:

• Traditional continuous casting processes often require high superheat temperatures.
• Maintaining molten steel purity during heating is crucial for final product quality.
• Existing slab casting equipment limitations necessitate innovative heating solutions.

Purpose of the Study:

• To evaluate the industrial effectiveness of a new graphite electrode plasma heating system in a tundish.
• To assess the impact of plasma heating on molten steel purity, specifically C, N, and O content.
• To determine the feasibility of plasma heating for continuous low superheat casting.

Main Methods:

• Installation and operation of a 1500 kW, three-electrode (2 cathode, 1 anode) plasma heating system in a double-strand slab caster tundish.
• Analysis of low and ultra-low carbon steel samples before and after plasma heating.
• Monitoring of molten steel temperature, throughput (5 t/min), and tundish capacity (50 t).
• Inclusion of inert gas to control the atmosphere and prevent reoxidation.

Main Results:

• Plasma heating did not increase N and O content; oxide inclusion size increased slightly with no significant change in quantity.
• Carbon content remained stable within 0.0001% fluctuation, indicating no significant carbon absorption.
• The system enabled a reduction in molten steel temperature by 10–15 °C, supporting low superheat casting.
• Heating rate reached 1.0 °C/min with inert gas protection preventing reoxidation.

Conclusions:

• The graphite electrode plasma heating system is viable for continuous casting of low carbon-nitrogen steel slabs.
• This technology offers benefits in reducing emissions and enhancing production efficiency.
• Plasma heating facilitates lower superheat temperatures, reducing costs and improving slab microstructure.