Steel Sheet Composition for Two-Piece Can Weight Reduction
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Solution Overview
Problem
Conventional steel sheets for two-piece cans face challenges in achieving high strength and formability while maintaining pressure-resistance and corrosion resistance, often requiring additional processing steps that increase costs and variability.
Innovation Solution
A steel sheet composition with specific mass percentages of C, Si, Mn, P, S, Al, and N, along with a film-laminated layer, is developed, and a manufacturing process involving high-temperature heating, hot-rolling, pickling, cold-rolling, annealing, and over-aging treatment to achieve optimal tensile strength, elongation, and yield elongation, ensuring reduced anisotropy and improved earing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of steel sheets is reduced to decrease weight and environmental load, then the amount of steel used is reduced, but the pressure-resistance strength of the can body is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (C: 0.010-0.050%, Si: ≤0.04%, Mn: 0.10-0.40%, P: 0.02% or less, S: 0.020% or less, Al: 0.030-0.100%, N: 0.0005-0.0030%, B: 0.0005-0.0030%) and processing parameters (heating temperature ≥1100°C, hot-rolling finish temperature 820-920°C, coiling temperature 600-700°C, annealing temperature 650-750°C) to achieve optimal mechanical properties in thin steel sheets, enabling reduced thickness while maintaining pressure-resistance strength
Solution Approach 2:
The patent employs composite material principles by creating a multi-layered structure consisting of the steel sheet base material with specific composition, a film-laminated layer for corrosion resistance, and controlled microstructure (ferrite grain size 5-20 μm, martensite ≤5%, bainite ≤5%), combining multiple functional layers to achieve both weight reduction and strength maintenance
2Strength
If highly strengthening steel sheets are used to compensate for reduction in pressure-resistance strength, then the strength is improved, but the processability is reduced and forming defects such as cracks occur
Solution Approach 1:
The patent applies parameter changes by controlling the chemical composition within specific ranges (particularly C: 0.010-0.050% and Mn: 0.10-0.40%) and implementing a multi-stage thermal-mechanical processing schedule (heating to ≥1100°C, hot-rolling at 820-920°C, coiling at 600-700°C, annealing at 650-750°C) to achieve a balanced microstructure that provides both high strength and good ductility for formability
Solution Approach 2:
The patent applies local quality principles by creating a controlled microstructure with specific grain size distribution (ferrite 5-20 μm) and phase composition (martensite ≤5%, bainite ≤5%) throughout the steel sheet, ensuring uniform local properties that prevent stress concentration and cracking during forming operations
3Strength
If steel sheets are highly strengthened to maintain pressure-resistance, then the strength is improved, but forming defects such as cracks occur in neck flange processing and can body part processing
Solution Approach 1:
The patent applies parameter changes by optimizing the chemical composition (C: 0.010-0.050%, Si: ≤0.04%, Mn: 0.10-0.40%, P: 0.02% or less, S: 0.020% or less, Al: 0.030-0.100%, N: 0.0005-0.0030%, B: 0.0005-0.0030%) and controlling the microstructure (ferrite grain size 5-20 μm, martensite ≤5%, bainite ≤5%) to achieve a balance between strength and ductility, preventing forming defects while maintaining pressure-resistance strength
Solution Approach 2:
The patent applies local quality principles by ensuring uniform distribution of phases and grain sizes throughout the steel sheet, creating consistent local mechanical properties that prevent stress concentration and cracking during neck flange processing and can body part processing operations
4Strength
If conventional steel sheets are used to achieve high strength, then the pressure-resistance strength is improved, but the anisotropy increases and earing characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the chemical composition (particularly C: 0.010-0.050%, Mn: 0.10-0.40%, Al: 0.030-0.100%) and implementing a specific thermal-mechanical processing schedule (heating to ≥1100°C, hot-rolling at 820-920°C, coiling at 600-700°C, annealing at 650-750°C) to achieve a microstructure with ferrite grain size of 5-20 μm and controlled phase distribution (martensite ≤5%, bainite ≤5%), which reduces anisotropy and improves earing characteristics while maintaining high strength
Solution Approach 2:
The patent applies local quality principles by creating a uniform microstructure with consistent grain size (5-20 μm) and phase distribution throughout the steel sheet, eliminating local variations that cause anisotropy and improving the uniformity of earing characteristics across the material
5Use of energy by stationary object
If coating steps are omitted to reduce energy costs and manufacturing complexity, then energy consumption is reduced and process complexity is simplified, but corrosion resistance may be compromised
Solution Approach 1:
The patent applies composite material principles by creating a multi-layered structure consisting of the steel sheet base material with specific composition (C: 0.010-0.050%, Si: ≤0.04%, Mn: 0.10-0.40%, P: 0.02% or less, S: 0.020% or less, Al: 0.030-0.100%, N: 0.0005-0.0030%, B: 0.0005-0.0030%) and a film-laminated layer applied to the surface, combining the high strength and formability of the controlled-composition steel with the corrosion resistance of the film layer, thereby eliminating the need for traditional coating steps while maintaining both mechanical and protective 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 solution provides a steel sheet with high strength and excellent formability in drawing and ironing processing, reducing manufacturing costs and variability, while maintaining corrosion resistance and pressure-resistance strength.
Implementation Method 1
heating a slab at a heating temperature of 1,100° C. or higher
Implementation Method 2
annealing, under the condition of an annealing temperature of 650° C. to 750° C., a cold-rolled sheet
Implementation Method 3
performing an over-aging treatment where a retention time in a temperature range of 380° C. to 500° C. is 30 s or more
Data Source
AI summary
A steel sheet for a two-piece can, the steel sheet includes: by mass %, C: 0.010% or more and less than 0.050%; Si: 0.04% or less; Mn: 0.10% or more and less than 0.40%; P: 0.02% or less; S:0.020% or less; Al: more than 0.030% and 0.100% or less; N: 0.0005% or more and less than 0.0030%; B: 0.0005% to 0.0030%; and balance Fe and inevitable impurities, wherein an amount of N that is present as BN and a whole amount of N satisfy the following expression (1):[N as BN]/[N]>0.5 (1),where N as BN represents the amount of N that is present as BN, and N represents the whole amount of N, tensile strength is 420 MPa to 540 MPa, elongation is 5% or more, yield elongation is 3% or less, and Δr is −0.50 to 0.10.