Control of High-Temperature Oxidation Loss in Heating Furnaces and Its Impact on Steel Quality

In steel production, the Steel heating furnace is an indispensable key equipment. During the heating of steel billets in the furnace, high-temperature oxidation loss inevitably occurs. This oxidation not only leads to material loss and increased production costs but also negatively impacts product quality, including surface defects, internal property degradation, and reduced yield. Currently, the oxidation loss rate of steel billets in domestic rolling heating furnaces is generally around 1.5%, sometimes even higher. For example, a steel mill producing 2 million tons annually would lose 30,000 tons per year at a 1.5% oxidation loss rate, equating to an economic loss of approximately 120 million RMB. Therefore, investigating effective methods to control high-temperature oxidation loss is crucial for improving product quality, reducing costs, and enhancing competitiveness in the steel industry.

Factors Affecting High-Temperature Oxidation Loss in Heating Furnaces

Oxidation occurs slowly at room temperature but accelerates significantly as temperature rises. When the temperature exceeds 1150°C, the oxidation reaction intensifies. At 1300°C, oxidation loss can be several times higher than at 1150°C. From a time perspective, the oxidation rate of carbon steel is positively correlated with furnace residence time; at 1100°C, each additional hour of heating increases oxidation loss by 0.3–0.5%. Furnace atmosphere is another critical factor. When the excess air coefficient exceeds 1.2, oxidative gas concentration increases sharply, raising oxidation rates by over 40%. Reducing oxygen partial pressure from 4% to 0.1% can reduce oxidation of 08Al steel by more than 70%. Billet surface roughness also matters; an increase of 10 μm in Ra expands contact area with oxidative gases by 15–20%, increasing loss. Alloy composition affects oxidation behavior; for example, each 1% increase in chromium enhances oxide layer density, reducing loss by 0.2%.

Strategies to Control High-Temperature Oxidation Loss

Optimize Heating Process Parameters

Enhance Furnace Temperature Measurement Accuracy

Install high-precision, stable high-temperature sensors near the furnace charging station. When billets reach the furnace entrance and are detected, the sensor immediately captures real-time temperature data, which is transmitted to the furnace control system to ensure precise heating control.

Adjust Heating Temperature Appropriately

For low-carbon steel, reduce the target billet temperature by approximately 20°C, based on production data and thermal principles, while ensuring uniform heating across furnace zones to prevent localized overheating and excessive oxidation.

Optimize Rolling Passes

Optimizing rolling sequences reduces energy consumption and improves steel quality. By implementing a 3+3 pass rolling process instead of 3+5, stress distribution is more uniform, billet oxidation loss is reduced, and fuel consumption drops. High-precision sensors and finite element simulations ensure optimal deformation and temperature control, improving both efficiency and product quality.

Comparison of 3+3 and 3+5 Rolling Pass Modes

Improve Furnace Atmosphere

Burner Calibration

Use advanced algorithms to calibrate each burner’s air-gas ratio, ensuring complete combustion and reducing oxidative gas levels in the furnace.

Increase Valve Accuracy

Measure air and gas pressures at manual and control valves, repairing or replacing components to achieve precise control, thus maintaining optimal furnace atmosphere and reducing billet oxidation.

Adjust Burner Nozzle Angle

Set nozzle angles between 80–85°, using computational fluid dynamics to direct air-fuel mixture to the furnace center, minimizing contact with side walls and reducing oxidation.

Enhance Billet Surface Treatment

Rust and Impurity Removal

Use a combination of mechanical grinding and chemical cleaning to remove surface rust and oils, reducing billets’ oxidation tendency during heating.

Improve Surface Smoothness

Polish billets using appropriate wheels and pressure settings to reduce surface roughness, limiting contact with oxidative gases, decreasing surface oxidation, and improving subsequent processing quality.

Optimize Furnace Equipment and Operations

Improve Charging Gap Control

Apply intelligent models and automation to calculate optimal billet spacing, accounting for thermal expansion and airflow disturbance. This ensures uniform heating, reducing defects and oxidation loss.

Enhance Production Rhythm

Upgrade to high-precision motors and variable-frequency drives, increasing conveyor speeds and reducing billet furnace residence time, thereby lowering oxidation losses while boosting productivity.

Conveyor Speed Before and After Upgrades (Unit: m/s)

Optimize Discharge Timing

Use precise sensor calibration and high-speed industrial communication to shorten intervals between furnace discharges, reducing waiting time and oxidation exposure for billets.

This study systematically analyzes the key factors affecting high-temperature oxidation loss in heating furnaces and their impact on steel quality. Furnace temperature, residence time, atmosphere, billet surface condition, and chemical composition critically influence oxidation rates. By optimizing heating parameters, furnace atmosphere, surface treatments, and equipment operations, steel producers can effectively control oxidation loss, improve steel quality, reduce production costs, and enhance market competitiveness.