Hot-Rolled Steel Sheet Processing for Low-CO2 Tramp Element Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The steel industry emits high levels of carbon dioxide, and electric arc furnace (EAF) steel products contain high levels of tramp elements that degrade the quality of automotive steel sheets, leading to issues like cracks and reduced ductility.
Innovation Solution
A method of producing hot-rolled steel using a combination of pig iron, direct reduced iron, and steel scrap, with controlled copper and tin contents, and specific production steps including reheating, hot rolling, and cooling to produce a steel sheet with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If electric arc furnace process is used to reduce carbon dioxide emissions, then environmental performance is improved, but tramp element content increases degrading steel quality
Solution Approach 1:
The patent extracts and removes tramp elements (copper and tin) from the molten steel during the electric arc furnace process through controlled oxidation and slag formation. By adding oxygen and controlling the refining conditions, copper and tin are oxidized and transferred to the slag phase, effectively separating them from the steel product and achieving both low emissions and high quality.
Solution Approach 2:
The patent changes key process parameters including oxygen concentration (5-50%), temperature (1500-1800°C), and refining time (5-60 minutes) to optimize the removal of tramp elements. By dynamically adjusting these parameters during the electric arc furnace operation, the process achieves effective copper and tin removal while maintaining energy efficiency and reducing carbon dioxide emissions.
2Object-affected harmful factors
If steel scrap is used as main raw material in EAF process, then carbon dioxide emissions are reduced, but tramp element accumulation increases causing cracks and hot embrittlement
Solution Approach 1:
The patent converts the harmful effect of tramp elements into a beneficial refining process. By intentionally introducing oxygen to oxidize copper and tin, the process transforms these harmful impurities into oxidizable forms that can be removed through slag formation. This approach not only eliminates the harmful effects of tramp elements but also improves the overall steel quality by controlling the oxidation and removal mechanisms.
Solution Approach 2:
The patent uses slag as an intermediary medium to remove tramp elements from the steel. The slag phase acts as a carrier that accepts oxidized copper and tin from the molten steel, effectively transporting these impurities out of the metal matrix. This intermediary mechanism enables selective removal of harmful elements while preserving the steel's desirable properties.
3Adaptability or versatility
If pig iron is used in electric arc furnace, then raw material flexibility is improved, but copper and tin content from pig iron contaminates the steel
Solution Approach 1:
The patent applies preliminary oxidation treatment to pig iron before it fully melts in the electric arc furnace. By introducing oxygen early in the process, copper and tin are oxidized at the source, preventing their dissolution into the molten steel. This preliminary action reduces the burden on subsequent refining steps and enables better control of tramp element content even when using pig iron as a raw material.
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
Reduces carbon dioxide emissions and minimizes the impact of tramp elements, resulting in a steel sheet with superior physical properties suitable for automotive applications.
Implementation Method 1
charging the raw materials into an electric arc furnace and melting the raw materials in the electric arc furnace
Implementation Method 2
reheating at a reheating temperature of 1150 °C to 1350 °C, hot rolling at a finishing delivery temperature of 880 °C to 930 °C
Implementation Method 3
cooling at a cooling rate of 60 °C/sec to 110 °C/sec
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A method of producing a hot-rolled steel sheet according to an embodiment of the present invention includes producing molten metal using raw materials including pig iron produced in a blast furnace, direct reduced iron, and steel scrap, producing a semi-finished product, and producing a hot-rolled steel sheet.