Continuous Hot Strip Production Without Intermediate Slab Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional steel production methods are energy-inefficient and result in high CO2 emissions, with separated production steps leading to intermediate cooling of slabs, which causes surface defects and reduces the quality of hot-rolled steel strips suitable for visually appealing surfaces.
Innovation Solution
A method involving the production of steel melts with specific chemical compositions, using electrically operated smelting units, continuous casting, and direct input into a heating unit above the austenite-ferrite transformation temperature to minimize ferrite volume fraction, allowing for high-quality hot-rolled steel strips without intermediate cooling, utilizing solid input materials and vacuum decarburization for low carbon and nitrogen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional integrated steel mills are used with separated production steps, then steel production can be achieved, but energy efficiency is poor and CO2 emissions are high
Solution Approach 1:
The patent combines the steelmaking process and continuous casting process into an integrated system where the steel melt is directly cast into slabs and then immediately fed into the rolling mill without intermediate cooling. This merging of processes eliminates energy waste from reheating and reduces CO2 emissions while maintaining production capability.
2Manufacturing precision
If slabs are cooled to ambient temperature for inspection and storage, then quality control can be performed, but surface defects occur and energy is wasted
Solution Approach 1:
The patent implements continuous production where slabs are directly fed from the continuous casting system into the heating unit and rolling mill without interruption or intermediate cooling. This continuous action maintains thermal energy, prevents surface defects, and eliminates the energy waste associated with cooling and subsequent reheating.
Solution Approach 2:
The patent changes the temperature parameter by maintaining slabs above the austenite-ferrite transformation temperature throughout the process. By controlling the temperature to remain in the austenite region, the steel maintains its plasticity and surface quality while being processed, avoiding the surface defects that occur during cooling.
3Ease of manufacture
If electrically operated melting units are used, then investment costs and CO2 emissions are reduced, but achieving deep decarburization and denitrification with high mass flow is difficult
Solution Approach 1:
The patent changes the chemical composition parameters by implementing deep decarburization (carbon < 0.02 wt.%) and denitrification (nitrogen < 70 ppm) through vacuum treatment and controlled refining. These parameter changes enable electrically operated melting units to achieve the required steel quality while maintaining high productivity through optimized processing parameters.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables energy-efficient production of high-quality hot-rolled steel strips with reduced surface defects, suitable for automotive and packaging applications, offering lower investment costs and reduced CO2 emissions, while maintaining high productivity and surface quality.
Implementation Method 1
setting the required rolling temperature, wherein the strand or the slab enters the heating unit directly at a temperature greater than A3-20 K, such that the volume fraction of ferrite in the near-surface regions of the strand or the slab is less than 5 vol %
Implementation Method 2
a) melting solid, ferrous starting material in a preferably electrically operated smelting unit
Implementation Method 3
c) feeding the melt into a vacuum system and decarburizing the melt in the vacuum system
Data Source
AI summary
A method for producing steel strip, in particular hot strip in the form of coiled coils or in the form of folded individual sheets, in which a steel melt is first produced, this is then formed into a strand in a continuous casting system, the strand is then fed into a heating unit and the heated strand is then rolled into hot strip in a subsequent rolling mill. The casting of the strand, the passage through the heating unit, and the rolling take place in a continuous process. To be able to produce hot-rolled steel strips in the most energy-efficient way possible and to make these strips available for further processing into high-quality cold-rolled and, if necessary, coated strips, the invention provides that, first of all, a steel melt is produced.