Copper-Steel Composite Materials in Electric Arc Furnaces: Enhancing Efficiency, Service Life, and Sustainability

Among modern steelmaking technologies, the Electric Arc Furnace (EAF) has become one of the fastest-growing production routes due to its lower carbon footprint, operational flexibility, and compatibility with renewable electricity.

As EAF productivity continues to increase, the thermal loads imposed on furnace components become more severe. Temperatures exceeding 1,600°C, intense radiation, molten steel splashing, and cyclic thermal stresses create significant challenges for cooling systems. Traditional cooling components manufactured from pure steel or pure copper each have inherent limitations:

· Carbon steel provides excellent mechanical strength but relatively poor thermal conductivity.

· Pure copper offers exceptional heat transfer performance but suffers from insufficient structural strength and higher material costs.

To overcome these limitations, copper-steel composite materials is an advanced engineering solution. By combining the excellent thermal conductivity of copper with the structural strength of steel through metallurgical bonding, copper-steel composites provide an ideal balance of performance, durability, and cost-effectiveness.

1. Operating Environment of Electric Arc Furnaces

Electric Arc Furnaces melt scrap steel or direct reduced iron (DRI) using electrical energy generated between graphite electrodes and the metal charge.

Critical furnace areas experience continuous exposure to:

· Arc radiation

· Molten steel splashing

· Slag erosion

· Thermal fatigue

· Mechanical vibration

Therefore, an efficient cooling system is essential for ensuring both equipment safety and production stability.

2. Why Copper-Steel Composite Materials?

Copper-steel composites combine two complementary materials into one integrated structure.

Copper Layer

Provides:

· Outstanding thermal conductivity

· Rapid heat dissipation

· Excellent resistance to thermal shock

· Reduced hot spots

Typical thermal conductivity: 380–400 W/m·K

Steel Layer

Provides:

· High structural strength

· Excellent rigidity

· Easy fabrication

· Lower overall material cost

· Better weldability to surrounding structures

Clad Structure

Unlike mechanical fastening or brazing, explosion welding creates a true metallurgical bond between copper and steel.

Typical interface characteristics include:

· No adhesive layer

· High bond strength

· Excellent fatigue resistance

· Stable thermal performance

· Reliable long-term operation

3. Manufacturing Technology

For large-area copper-steel clad plates (e.g., > 5 meters in length), explosion welding (explosive cladding) is the most widely recognized and reliable manufacturing method worldwide. This process ensures high bond integrity suitable for critical EAF cooling applications.

The typical production sequence includes:

a) Surface preparation (polishing of copper and steel mating surfaces)

b) Precision assembly (setting controlled stand-off distance)

c) Explosive charge calculation and detonation (high-velocity oblique impact)

d) Metallurgical bonding (instantaneous high temperature and pressure form a wavy interlock interface)

a) Post-weld heat treatment (stress relief and flattening, if required)

b) 100% ultrasonic non-destructive testing (ASME SA-432, or equivalent standards)

c) Mechanical property verification (shear, tensile, and bend tests)

d) Final precision machining (drilling, edge beveling, and forming as per engineering drawings)

The resulting wavy interface morphology not only maximizes bond strength but also provides excellent resistance to thermal fatigue—a critical factor in cyclic EAF operations.

1. Material Selection Considerations

The performance of copper-steel composite components depends on careful material selection.

Common copper grades include:

· C11000 (ETP Copper)

· Cu-DHP

· Oxygen-Free Copper

Typical backing steel materials include:

· ASTM A516 Grade 70

· ASTM A36

· Q235B

· Q345R

As Electric Arc Furnace technology continues to evolve toward larger capacities, ultra-high-power operation, and higher productivity, the design priorities for electrode arms have shifted from simply maximizing cooling performance to achieving an optimal balance between electrical conductivity, mechanical strength, structural weight, and maintenance efficiency.

In recent years, high-strength aluminum alloy electrode arms have become the preferred solution for many newly built EAFs. Their significantly lower density—approximately one-third that of steel—reduces the moving mass of the electrode lifting system, allowing faster electrode positioning, lower mechanical inertia, and improved dynamic response during furnace operation. Aluminum also offers good electrical conductivity, making it well suited for modern conductive arm designs.

However, copper-steel composite materials continue to offer unique advantages in demanding thermal environments. The combination of copper's superior thermal conductivity with the structural strength of steel provides excellent resistance to localized overheating, high thermal loads, and mechanical fatigue. Copper-steel composites remain an attractive choice for applications where thermal management, durability, and long service life are prioritized, such as cooling panels, cooling staves, furnace roof components, and other water-cooled furnace structures.