Twin-Roll Casting Temperature Control via Si Additive
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing cast strip manufacturing methods using twin-roll casters face challenges in maintaining a stable equiaxed crystal ratio due to fluctuations in molten steel temperature, leading to defects and casting issues like nozzle clogging and hot bands, as precise temperature control is difficult to achieve.
Innovation Solution
The method involves adding a Si additive to the molten steel in the tundish, adjusting its concentration within a fixed range to control the molten steel temperature, using Si-containing materials with varying Si contents and blending ratios to maintain a stable temperature, thereby ensuring a consistent equiaxed crystal ratio in the cast strip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the molten steel temperature in the tundish is reduced to increase the equiaxed crystal ratio, then the equiaxed crystal ratio is improved, but the molten steel temperature becomes too low at the initial and final stages of casting, causing nozzle clogging and hot bands
Solution Approach 1:
The patent applies preliminary action by adding a Si additive to the molten steel in the tundish before casting to pre-generate heat through exothermic oxidation reactions. This preliminary heat generation compensates for temperature drops at the initial and final stages of casting, preventing nozzle clogging and hot bands while maintaining the lower molten steel temperature needed for high equiaxed crystal ratio throughout the casting process.
Solution Approach 2:
The patent changes the chemical composition parameter by adding Si additive (containing Si, Al, and Ca) to the molten steel, which triggers exothermic oxidation reactions. This parameter change generates heat in-situ, dynamically compensating for temperature variations during casting and stabilizing the thermal conditions for consistent equiaxed crystal formation.
2Reliability
If the molten steel temperature is increased to prevent nozzle clogging and hot bands, then the casting reliability is improved, but the equiaxed crystal ratio decreases due to excessive temperature
Solution Approach 1:
The patent applies local quality by generating heat locally within the molten steel through exothermic oxidation of Si additive. This localized heat generation occurs precisely where needed (in the molten steel pool) and precisely when needed (during casting stages with temperature drop), providing targeted temperature compensation without globally increasing the molten steel temperature, thus preserving high equiaxed crystal ratio.
Solution Approach 2:
The patent converts the potentially harmful effect of temperature drop (which causes nozzle clogging and hot bands) into a beneficial trigger for exothermic oxidation reactions. By adding Si additive, the temperature drop activates the heat-generating oxidation reactions, which then compensate for the temperature drop and maintain optimal casting conditions throughout the process.
3Adaptability or versatility
If the molten steel temperature fluctuates during casting, then the casting process adapts to thermal changes, but the equiaxed crystal ratio changes and the cast structure becomes unstable in the longitudinal direction
Solution Approach 1:
The patent implements feedback by using temperature sensors to monitor molten steel temperature during casting and dynamically adjusting the addition rate of Si additive based on real-time temperature measurements. When temperature drops are detected, the system increases Si additive addition to generate more heat through oxidation; when temperature is stable, the addition rate is reduced. This closed-loop feedback control stabilizes the equiaxed crystal ratio throughout the casting process.
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 allows for accurate control of the molten steel temperature, stabilizing the equiaxed crystal ratio and preventing casting defects, ensuring a stable and efficient production process by maintaining the temperature within a fixed range.
Implementation Method 1
a Si additive is added to the molten steel in the tundish from an initial stage to a final stage of casting, a Si concentration of the molten steel is adjusted to be within a fixed range, and a temperature of the molten steel in the tundish is controlled to be within a fixed range
Implementation Method 2
a molten steel is supplied to a molten steel pool portion formed by a pair of rotating cooling rolls and a pair of side dams via an immersion nozzle, and forming and growing a solidified shell on a circumferential surface of the cooling roll
Implementation Method 3
the molten steel is rapidly cooled at the time of solidification, and thus columnar crystals are formed from surface layers of both sides toward a 1⁄2-thick portion
Data Source
AI summary
There is provided a cast strip manufacturing method including: supplying a molten steel stored in a tundish (18) to a molten steel pool portion (16) formed by a pair of rotating cooling rolls (11) and a pair of side dams via an immersion nozzle (20); and forming and growing a solidified shell on a circumferential surface of the cooling roll (11) to manufacture a cast strip (1), in which a Si additive is added to the molten steel in the tundish (18), a Si concentration of the molten steel is adjusted to be within a fixed range, and a temperature of the molten steel in the tundish (18) is controlled to be within a fixed range.