Multiphase Tinned Steel Plate Strength Elongation Balance
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Solution Overview
Problem
Existing methods for producing high-strength tinned steel plates face challenges in achieving a balance between strength and elongation, with rapid annealing processes being difficult to control and costly, and high reduction rates leading to low elongation and formability issues.
Innovation Solution
A high-strength multiphase steel tinned raw plate with a specific chemical composition and manufacturing process, including controlled carbon, manganese, aluminum, phosphorus, and nitrogen content, and a structured microstructure of ferrite, pearlite, and cementite, subjected to continuous annealing and double cold reduction, to achieve yield strength and elongation within specified ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ultra-low carbon content steel (5-40 ppm carbon) is used to guarantee elongation, then elongation is improved, but steel-making cost increases due to additional vacuum decarburization
Solution Approach 1:
The patent changes the carbon content parameter from ultra-low (5-40 ppm) to low (0.01-0.05%), and introduces a specific manganese content range (0.1-1.2%) to achieve the desired elongation without requiring expensive vacuum decarburization processes. This parameter adjustment resolves the contradiction by finding an optimal balance point that satisfies both elongation requirements and manufacturing cost constraints.
2Strength
If high reduction rate (20-50%) in double cold reduction is applied to increase strength, then strength is improved, but elongation decreases making the steel unsuitable for applications requiring formability
Solution Approach 1:
The patent optimizes the reduction rate parameter to a specific range (10-30%) rather than using extreme high reduction rates (20-50%). Combined with controlled alloy composition (specific C, Mn, Al, P, N ranges), this moderate reduction rate achieves the required strength while preserving sufficient elongation for formable applications.
3Weight of moving object
If tinned plate thickness is continuously reduced to meet energy conservation and cost reduction requirements, then weight and cost are reduced, but strength requirements become more stringent to guarantee normal use
Solution Approach 1:
The patent creates a multiphase composite steel structure consisting of ferrite, pearlite, and martensite phases. This composite microstructure achieves high strength (tensile strength ≥500 MPa) in thin plates through phase combination and distribution, enabling thickness reduction while meeting stringent strength requirements for thin-walled applications.
4Strength
If low-temperature annealing is applied to increase strength, then strength is improved, but additional process control is required to maintain elongation
Solution Approach 1:
The patent specifies a precise annealing temperature range (500-650°C) and combines it with controlled cooling rates and specific alloy composition parameters. This coordinated parameter control achieves strength enhancement through low-temperature annealing while maintaining elongation, avoiding the need for overly complex process control systems.
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 results in a tinned raw plate with high strength and good elongation, suitable for applications like three-piece cans and easy-to-open caps, while reducing steel-making costs and facilitating easier industrial production by avoiding vacuum decarburization and allowing for precise control of annealing temperatures and cooling rates.
Implementation Method 1
the steel plate is subjected to continuous annealing and double cold reduction, wherein a temperature T in the continuous annealing stage is (727-100×C-30×Mn-1000×N)°C≤T≤800°C; a hold time is 30 s-50 s; a cooling rate in a zone having a temperature of 250 °C or higher is 50-90 °C/s
Data Source
Figure 1~2
AI summary
Disclosed are a high-strength multiphase steel tinned raw plate and a manufacturing method therefor, wherein the mass percentages of the components of the multiphase steel tinned raw plate are: 0.081%-0.14% of C, 0.2%-0.8% of Mn, 0.01 %-0.09% of Al, 0.01%-0.03% of P, 0.002%-0.015% of N, also containing one or more than one of 0.001%-0.005% of B, 0.005%-0.05% of Cr, 0.001%-0.1% of Ti, 0.001%-0.2% of Nb, 0.005%-0.03% of Cu, 0.001%-0.008% of Mo, and the balance of Fe and other inevitable impurities; and satisfy: 0.21% ≤ Mn + 1.3 Cr + 3.2 Mo + 0.5 Cu ≤ 0.91%. The tinned raw plate has a structure comprising ferrite grains, pearlite, martensite and cementite particles, wherein the total volume fraction of the pearlite, martensite and cementite particles is 5%-20%, the volume fraction of the martensite is 1%-5%, and the martensite has a solid solution content of carbon of ≥ 0.07%. The tinned raw plate has a high strength and better elongation, and can be used to produce a can body, a can bottom, an easy-open end and a twist-off cap, etc. of a three-piece can which has higher requirements for strength and elongation.