Tinned Primary Plate Double Cold Reduction Elongation
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Solution Overview
Problem
The double cold reduction (DCR) method for manufacturing tinned plates results in lower elongations, especially in the 45° and perpendicular directions, which can lead to cracking during punching processes, limiting the market application of DCR tinned plates, particularly for parts requiring high elongation like easy-open lids and standard lids.
Innovation Solution
A high-strength, high-elongation tinned primary plate is developed using a specific alloy composition with carbon, manganese, aluminum, nitrogen, and additional elements, subjected to a controlled double cold reduction of 5-13% and rolling tension of 50-100 MPa, resulting in a microstructure of ferrite and banded cementite, ensuring yield strength of Rp0.2≥520 MPa and elongations ≥10% in all directions after bake-hardening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If double cold reduction (DCR) method is used to manufacture tinned plates, then the strength of the plate is improved and thickness is reduced, but the elongation in 45° direction and perpendicular direction (TD) decreases significantly
Solution Approach 1:
The patent applies parameter changes by precisely controlling the reduction ratio of the second cold reduction process (5-13%) and applying specific rolling tension (50-100 MPa) during DCR. It also controls alloy composition parameters (C: 0.065-0.12%, Mn: 0.2-0.8%, Al: 0.01-0.08%, N: 0.003-0.015%) to achieve the optimal balance between strength and elongation, resolving the contradiction between strength improvement and elongation maintenance.
Solution Approach 2:
The patent creates a composite microstructure consisting of ferrite and banded cementite through controlled DCR processing. This composite structure at the micro level provides both the strength from cementite bands and the ductility from ferrite matrix, enabling the plate to achieve high yield strength (≥520 MPa) while maintaining high elongation (≥10%) in all directions after bake-hardening.
2Strength
If the baseplate undergoes surface painting and baking process (bake-hardening) before punching, then the strength is improved, but the elongation in various directions decreases causing cracks during punching
Solution Approach 1:
The patent applies preliminary action by performing controlled DCR processing before bake-hardening to pre-establish the optimal microstructure (ferrite with banded cementite) and mechanical properties. This preliminary microstructural preparation ensures that the material can withstand subsequent bake-hardening without excessive loss of elongation, and can still resist cracking during punching operations.
Solution Approach 2:
The patent controls the composition parameters (particularly C: 0.065-0.12% and N: 0.003-0.015%) to optimize the response to bake-hardening. The controlled carbon and nitrogen content, combined with Mn and Al additions, ensures that bake-hardening increases strength to ≥520 MPa while maintaining elongation at ≥10% in all directions, preventing cracking during subsequent punching.
3Strength
If high reduction of double cold reduction (15-35% or higher) is applied, then the strength and thinning are improved, but the lateral elongation and anisotropy worsen significantly
Solution Approach 1:
The patent applies parameter changes by limiting the reduction ratio of the second cold reduction to 5-13% (significantly lower than conventional 15-35% or higher) and applying rolling tension of 50-100 MPa. This parameter optimization prevents excessive anisotropy development and maintains lateral elongation, while still achieving the desired strength increase and thickness reduction for thin-walled can and lid applications.
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 effectively enhances yield strength while maintaining high elongations in all directions after bake-hardening, preventing cracking and expanding the market application of DCR tinned plates for parts like easy-open lids and standard lids.
Implementation Method 1
the primary plate is processed by double cold reduction at a reduction of 5 ̃13% and a rolling tension of 50 ̃100 MPa
Implementation Method 2
the primary plate is processed by double cold reduction at a reduction of 5 ̃13% and a rolling tension of 50 ̃100 MPa
Implementation Method 3
A high-strength, high-elongation tinned primary plate is developed using a specific alloy composition with carbon, manganese, aluminum, nitrogen
Implementation Method 4
after bake-hardening. The tinned primary plate is suitable for forming parts such as easy-open lids and standard lids
Data Source
AI summary
A high-strength high-elongation tinned primary plate and a double cold reduction method therefor. The tinned primary plate comprises the following components by weight from 0.065 to 0.12% of carbon, from 0.2 to 0.8% of manganese, from 0.003 to 0.015% of nitrogen, the remainder being iron and the inevitable trace impurities. The tinned primary plate is necessarily subjected to double cold reduction at a reduction of 5˜13% and a rolling tension of 50˜100 MPa. The tinned primary plate has a yield strength of Rp0.2≥520 MPa, and percentage elongations in rolling direction RD, 45° direction and perpendicular direction TD, which are all greater than or equal to 10% after bake-hardening.