Copper Alloy Plate Composition for Strength and Bendability
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Solution Overview
Problem
Conventional copper alloy plates used for electric and electronic parts, such as connectors, face challenges in achieving a balance between strength, bending workability, stress corrosion cracking resistance, and stress relaxation resistance while maintaining low costs and high conductivity, with existing solutions like phosphor bronzes being costly and brasses having limited strength and poor bending workability.
Innovation Solution
A copper alloy plate with a chemical composition of 17-32% zinc, 0.1-4.5% tin, 0.5-2.5% silicon, 0.01-0.3% phosphorus, and optional additional elements, processed through a method involving hot-rolling, multiple cold-rolling steps, intermediate annealing, and low-temperature annealing to achieve a specific crystal orientation and grain size, enhancing strength, bending workability, and stress corrosion cracking resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength of brass is improved by increasing the finish rolling reduction, then the tensile strength increases, but the bending workability in directions perpendicular to the rolling directions is remarkably deteriorated
Solution Approach 1:
The invention changes the crystal orientation parameter (I{220}/I{420} ratio) through controlled hot-rolling and cold-rolling processes to achieve both high strength and good bending workability. By adjusting the rolling reduction ratios and temperatures, the patent creates a specific texture where the {220} planes are oriented favorably, allowing the material to exhibit high tensile strength while maintaining bending workability that would normally be lost at high strength levels.
2Strength
If a copper alloy plate has high strength, then it can withstand stress during assembly and operation, but the bending workability is deteriorated
Solution Approach 1:
The patent achieves high strength with good bending workability by controlling the crystal orientation parameter I{220}/I{420} to be 2.0 or more. This is accomplished through specific hot-rolling and cold-rolling processes that create a favorable texture, allowing the material to simultaneously exhibit high tensile strength (550 MPa or more) and adequate bending workability (R/t value of 0.5 or less).
Solution Approach 2:
The invention uses a composite alloy system (Cu-Zn-Sn-Si-P) where multiple elements work together to achieve both high strength and good bending workability. The specific composition ranges (Zn: 17-32%, Sn: 0.1-4.5%, Si: 0.5-2.5%, P: 0.01-0.3%) create a material with enhanced mechanical properties while maintaining formability, resolving the trade-off between strength and bending workability.
3Strength
If the strength level is increased to achieve high tensile strength, then the material can withstand stress, but the stress corrosion cracking resistance is deteriorated
Solution Approach 1:
The patent employs a composite alloy system (Cu-Zn-Sn-Si-P) where the synergistic effect of multiple elements provides both high strength and excellent stress corrosion cracking resistance. The specific composition ranges create a material that achieves tensile strength of 550 MPa or more while maintaining superior resistance to stress corrosion cracking, overcoming the limitation of conventional brasses.
4Strength
If conventional phosphor bronze is used to achieve good balance of strength and corrosion resistance, then the material properties are improved, but the cost is increased due to expensive tin content
Solution Approach 1:
The invention replaces expensive tin (Sn) with cheaper silicon (Si) and phosphorus (P) elements to achieve similar or better mechanical properties. By using the Cu-Zn-Si-P alloy system with optimized composition ranges, the patent reduces raw material costs significantly while maintaining or improving strength, bending workability, and stress corrosion cracking resistance compared to conventional phosphor bronzes.
Solution Approach 2:
The patent changes the alloying strategy by limiting tin content to 0.1-4.5% (much lower than conventional phosphor bronzes) and instead optimizing silicon (0.5-2.5%) and phosphorus (0.01-0.3%) content. This parameter change achieves the desired mechanical properties at lower cost while also improving environmental compatibility and recyclability.
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 cost-effective copper alloy plate with improved strength, bending workability, and stress corrosion cracking resistance, suitable for miniaturized electronic components, while maintaining high conductivity and stress relaxation resistance.
Implementation Method 1
a crystal orientation wherein I{220}/I{420} is in the range of from 2.5 to 8.0 assuming that the X-ray diffraction intensity on {220} crystal plane on the plate surface of the copper alloy plate is I{220} and that the X-ray diffraction intensity on {420} crystal plane thereon is I{420}
Implementation Method 2
processed through a method involving hot-rolling, multiple cold-rolling steps, intermediate annealing, and low-temperature annealing
Implementation Method 3
processed through a method involving hot-rolling, multiple cold-rolling steps, intermediate annealing, and low-temperature annealing to achieve a specific crystal orientation and grain size
Data Source
AI summary
There are provided an inexpensive copper alloy plate having excellent bending workability, excellent stress corrosion cracking resistance and excellent stress relaxation resistance while maintaining the high strength thereof, and a method for producing the same. The copper alloy plate has a chemical composition which contains 17 to 32% by weight of zinc, 0.1 to 4.5% by weight of tin, 0.5 to 2.5% by weight of silicon, 0.01 to 0.3% by weight of phosphorus and the balance being copper and unavoidable impurities, the total of the content of silicon and six times as much as the content of phosphorus being 1% by weight or more, the copper alloy plate having a crystal orientation wherein I{220}/I{420} in the range of from 2.5 to 8.0 assuming that the X-ray diffraction intensity on {220} crystal plane on the plate surface of the copper alloy plate is I{220} and that the X-ray diffraction intensity on {420} crystal plane thereon is I{420}.