Thin Slab Casting and Rolling to Reduce Segregation in Steel Sheet
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Solution Overview
Problem
The manufacturing of thin steel sheets with high alloy steel systems using the TSCR method faces challenges due to significant segregation, which affects material quality and surface aesthetics, and the inability to improve segregation through soaking treatments.
Innovation Solution
An apparatus and method that combine continuous casting, a holding furnace, and finish rolling without cutting the slab, where the slab is reduced by 30% or more after solidification and held at high temperatures in the holding furnace for extended periods to reduce segregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If TSCR method is used to manufacture thin steel sheets, then rolling load is reduced and passability is improved, but significant segregation occurs affecting material quality and surface aesthetics
Solution Approach 1:
The patent applies preliminary action by performing a reduction process immediately after solidification completion in the continuous casting machine, before the slab enters the holding furnace. This preliminary reduction of 30% or more creates initial conditions that enable subsequent segregation improvement during holding, allowing the TSCR process to achieve both low rolling load and reduced segregation.
2Productivity
If slab is immediately rolled in TSCR without soaking treatment, then continuous manufacturing efficiency is maintained, but segregation cannot be improved
Solution Approach 1:
The patent introduces a preliminary reduction step immediately after solidification completion, before the slab enters the holding furnace. This preliminary action modifies the slab structure in advance, creating conditions that enable segregation improvement during the subsequent holding period without interrupting the continuous manufacturing flow.
Solution Approach 2:
The patent changes key process parameters: performing reduction at a rolling reduction of 30% or more when the center temperature is 1300°C or higher, and holding at 1150-1300°C for 5 minutes or longer. These parameter changes enable segregation improvement while maintaining continuous manufacturing efficiency.
3Stability of the object's composition
If reduction is performed after solidification completion at high temperature, then segregation is reduced, but energy consumption increases
Solution Approach 1:
The patent merges the reduction process with the continuous casting operation by performing reduction immediately after solidification completion within the casting machine or at its outlet. This integration allows the slab to be reduced while still at high temperature from the casting process, avoiding the need for separate heating and holding operations that would consume additional energy.
Solution Approach 2:
The patent utilizes the thermal energy already present in the slab from the continuous casting process. By performing reduction when the center temperature is 1300°C or higher (self-generated heat from casting), the process eliminates the need for external heating energy input that would otherwise be required to reach such high temperatures for reduction.
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 approach enables the stable production of thin steel sheets with reduced segregation, improving material quality and surface finish, while also reducing rolling loads and enhancing passability in the rolling process.
Implementation Method 1
the slab is reduced by 30% or more after solidification and held at high temperatures in the holding furnace for extended periods to reduce segregation
Implementation Method 2
continuous casting of thin slabs
Data Source
AI summary
Using an apparatus for manufacturing a thin steel sheet including the followings which are arranged in order: a continuous casting machine (1) for a thin slab having a slab thickness of 70 mm to 120 mm at a lower end of a mold; a holding furnace (2) that is configured to maintain a temperature of a cast slab (10) and/or heats the cast slab (10); and a rolling stand (3) by which finish rolling is performed, the casting speed of the thin slab is set to 4 to 7 m/min, the slab (10) is reduced at a rolling reduction of 30% or more by the reduction roll (4) after solidification is completed and when a center temperature of the slab is 1300° C. or higher, and the slab (10) is held at a temperature of 1150° C. or higher and 1300° C. or lower for five minutes or longer in the holding furnace (2).