Steel Sheet Dislocation Control for Crown Cap Forming
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Solution Overview
Problem
Steel sheets used for crown caps and DRD cans face issues with insufficient formability and strength after sheet metal thinning, leading to lower impact resistance and shape defects, which affect sealing performance and consumer confidence.
Innovation Solution
Optimizing alloy components and manufacturing conditions to control dislocation density at a depth position of 1/2 of the sheet thickness, with specific chemical compositions and processing steps such as hot rolling, pickling, primary and secondary cold rolling, and annealing, to achieve a dislocation density range of 2.0 × 10^14 to 1.0 × 10^15 /m², enhancing both strength and formability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the thickness of the steel sheet for crown caps is reduced to less than 0.22 mm for cost reduction, then material cost is reduced, but pressure resistance and impact resistance become insufficient
Solution Approach 1:
The invention changes the material parameters by precisely controlling chemical composition (C: 0.0010-0.0060%, Si: 0.005-0.050%, Mn: 0.10-0.50%, etc.) and microstructure parameters (dislocation density, grain size) to achieve high strength in thin sheets. This allows using thinner steel sheets while maintaining sufficient pressure resistance and impact resistance through optimized material properties rather than relying solely on thickness.
2Ease of manufacture
If the steel sheet has low formability, then manufacturing is easier, but shape defects occur during crown cap forming
Solution Approach 1:
The invention optimizes formability by controlling microstructural parameters including dislocation density (5.0×10^14 to 2.0×10^15 /m²), grain size, and phase composition. This creates a material that is sufficiently formable to prevent shape defects during crown cap forming while maintaining the manufacturing process simplicity through controlled rolling and annealing parameters.
3Loss of substance
If the steel sheet has insufficient formability after thinning, then cost reduction is achieved, but shape defects such as folds and wrinkles occur
Solution Approach 1:
The invention achieves high formability in thin steel sheets by precisely controlling chemical composition (particularly C: 0.0010-0.0060% and Si: 0.005-0.050%) and microstructure (dislocation density, grain size distribution). This enables thin sheets to be formed without shape defects through optimized material properties that enhance ductility and formability despite reduced thickness.
4Ease of manufacture
If conventional SR material is used for thin sheets, then manufacturing is simple, but pressure resistance and impact resistance are insufficient
Solution Approach 1:
The invention enhances strength parameters (pressure resistance and impact resistance) by optimizing chemical composition (adding controlled amounts of Mn: 0.10-0.50%, Ti: 0.010-0.100%, Nb: 0.010-0.080%, B: 0.0005-0.0080%) and controlling microstructure (dislocation density, phase composition). This allows conventional simple manufacturing processes to produce thin sheets with significantly improved strength properties.
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 resulting steel sheets maintain high impact resistance and prevent shape defects, ensuring proper sealing and reduced waste in manufacturing, even after thinning, by achieving sufficient formability and strength.
Implementation Method 1
Optimizing alloy components and manufacturing conditions to control dislocation density at a depth position of 1/2 of the sheet thickness, with specific chemical compositions and processing steps such as hot rolling, pickling, primary and secondary cold rolling, and annealing, to achieve a dislocation density range of 2.0 × 10^14 to 1.0 × 10^15 /m², enhancing both strength and formability
Implementation Method 2
processing steps such as hot rolling, pickling, primary and secondary cold rolling, and annealing
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Provided is a steel sheet having sufficient formability and strength even after sheet metal thinning, the steel sheet including: a chemical composition containing, by mass%, C: more than 0.0060 % and not more than 0.012 %, Si: 0.02 % or less, Mn: 0.10 % or more and 0.60 % or less, P: 0.020 % or less, S: 0.020 % or less, Al: 0.01 % or more and 0.07 % or less, and N: 0.0080 % or more and 0.0200 % or less, with the balance being Fe and inevitable impurities, in which a dislocation density at a depth position of 1/2 of a sheet thickness from a surface of the steel sheet is 2.0 × 1014/m2 or more and 1.0 × 1015/m2 or less.