Ultra-Low Carbon Steel Slab Width Reduction for Blister Suppression
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Solution Overview
Problem
Existing methods fail to effectively suppress blister defects in ultra-low carbon steel products, as bubbles captured in the solidified shell during casting can still cause defects during hot rolling and subsequent processes, leading to yield reduction and surface quality issues.
Innovation Solution
A method involving a refining step to adjust carbon concentration, a casting step to form a slab, and a hot rolling step with a width reduction process to deform bubbles, optionally followed by cold rolling at a predetermined reduction ratio, to suppress blister defects. This method includes using a sizing press for width reduction and controlling the rolling reduction ratio to minimize bubble expansion and surface deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the slab is hot rolled without width reduction, then production efficiency is maintained, but bubbles in the solidified shell expand during heating causing blister defects
Solution Approach 1:
The width reduction step is introduced as a preliminary action before hot rolling to prevent bubble expansion. By deforming the slab structure in advance, the patent eliminates the cause of blister defects before the heating process that would otherwise cause bubble expansion. This maintains production efficiency while ensuring surface quality.
Solution Approach 2:
The patent changes the physical parameters of the slab by performing width reduction with a specific reduction amount (50-200 mm) before hot rolling. This parameter change in slab dimensions and internal structure prevents the harmful expansion of bubbles during subsequent heating, thereby suppressing blister defect formation while maintaining production efficiency.
2Reliability
If width reduction is performed with a large reduction amount, then bubble deformation is enhanced suppressing blister defects, but production time and energy consumption increase
Solution Approach 1:
The patent optimizes the width reduction parameter within a specific range (50-200 mm) to achieve effective bubble deformation while minimizing energy consumption and production time. This parameter optimization ensures sufficient bubble suppression without excessive energy input or time extension, balancing reliability improvement with energy efficiency.
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
The method significantly reduces blister defect occurrence rates, improving production line yield and surface quality by deforming bubbles and increasing steel sheet strength through controlled width reduction and rolling processes.
Implementation Method 1
a width reduction step of performing width reduction on the slab to be subjected to the hot rolling step with a reduction amount which is predetermined in accordance with the slab width
Implementation Method 2
a hot rolling step of hot rolling the slab to obtain a hot-rolled steel sheet
Implementation Method 3
a cold rolling step of cold rolling the hot-rolled steel sheet to obtain a cold-rolled steel sheet
Data Source
AI summary
A method for producing an ultra-low carbon steel product having a carbon concentration of 0.005% by mass or less includes, at least, a step of adjusting a carbon concentration of molten iron to obtain molten steel, a step of casting the molten steel into a slab, and a step of hot rolling the slab to obtain a hot-rolled steel sheet, in which the method further includes a width reduction step of performing width reduction on the slab with a reduction amount which is predetermined in accordance with the slab width in a direction orthogonal to the rolling direction of the slab.