Cu-Zn-Sn-Si-Ni Alloy Sheet for Connector Strength and Workability
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Solution Overview
Problem
Conventional copper alloy sheet materials for electric and electronic parts, such as connectors, face challenges in achieving a balance between high strength, excellent bending workability, and stress corrosion cracking resistance while maintaining low production costs and environmental sustainability.
Innovation Solution
A copper alloy sheet material with a chemical composition of 17 to 32% zinc, 0.1 to 4.5% tin, 0.01 to 2.0% silicon, and 0.01 to 5.0% nickel, produced through a process involving melting, casting, hot-rolling, cooling, cold-rolling, recrystallization annealing, ageing annealing, and optional finish cold-rolling and low-temperature annealing, to enhance mechanical properties and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength of brasses 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 chemical composition parameters of the brass alloy by adding specific amounts of tin (0.01-4.5 wt%), silicon (0.01-2.0 wt%), and nickel (0.01-5.0 wt%), along with zinc (17-32 wt%). This compositional parameter change enables the material to achieve high tensile strength (≥550 MPa) while maintaining excellent bending workability, resolving the contradiction between strength improvement and bending performance deterioration that occurs with conventional finish rolling reduction methods
Solution Approach 2:
The invention creates a multi-element composite copper alloy system (Cu-Zn-Sn-Si-Ni) that combines the benefits of different alloying elements. Tin provides strength enhancement, silicon improves corrosion resistance and mechanical properties, and nickel contributes to both strength and ductility. This composite alloy structure achieves superior comprehensive performance including high tensile strength (≥550 MPa), excellent bending workability, and improved stress corrosion cracking resistance without compromising any single property
2Reliability
If phosphor bronze is used to achieve excellent balance between strength, corrosion resistance, stress corrosion cracking resistance and stress relaxation resistance, then the mechanical properties are improved, but the raw material costs are increased due to about 6% expensive tin content
Solution Approach 1:
The invention significantly reduces the tin content from the conventional 6% in phosphor bronze to a controlled range of 0.01-4.5 wt%, while compensating for the reduced tin content by adding silicon (0.01-2.0 wt%) and nickel (0.01-5.0 wt%). This parameter change in chemical composition maintains excellent stress corrosion cracking resistance and mechanical properties while substantially lowering raw material costs and improving recyclability
Solution Approach 2:
The invention replaces expensive tin (6% in conventional phosphor bronze) with more cost-effective alloying elements, specifically utilizing zinc (17-32 wt%), silicon (0.01-2.0 wt%), and nickel (0.01-5.0 wt%) to achieve similar or superior performance. This substitution with cheaper elements reduces raw material costs while maintaining the required reliability and stress corrosion cracking resistance for electric and electronic parts
3Quantity of substance
If brass is used to achieve low raw material costs and low production costs with excellent recycling efficiency, then the cost is reduced, but the strength is lower than phosphor bronze and stress corrosion cracking resistance is not excellent
Solution Approach 1:
The invention modifies the conventional brass composition by adding tin (0.01-4.5 wt%), silicon (0.01-2.0 wt%), and nickel (0.01-5.0 wt%) to the Cu-Zn base system. This parameter change in chemical composition enables the alloy to achieve high tensile strength (≥550 MPa), excellent stress corrosion cracking resistance, and good bending workability while maintaining relatively low raw material costs and production costs compared to high-tin phosphor bronze
Solution Approach 2:
The invention creates a multi-element composite brass alloy (Cu-Zn-Sn-Si-Ni) that combines the cost-effectiveness of brass with the enhanced properties of phosphor bronze. The synergistic interaction between zinc (17-32 wt%), tin (0.01-4.5 wt%), silicon (0.01-2.0 wt%), and nickel (0.01-5.0 wt%) produces a material that achieves both economic viability and superior mechanical properties, including high strength (≥550 MPa), excellent stress corrosion cracking resistance, and good 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 resulting sheet material exhibits improved bending workability, stress corrosion cracking resistance, and high strength, with a longer crack observation time and reduced coarse deposits, suitable for producing miniaturized and thinned electric and electronic parts with enhanced reliability and recyclability.
Implementation Method 1
hot-rolling the cast copper alloy in a temperature range of from 900° C. to 400° C.
Implementation Method 2
cooling the hot-rolled copper alloy at a cooling rate of 1 to 15° C./minute from 400° C. to 300° C.
Implementation Method 3
recrystallization-annealing the cold-rolled copper alloy at a temperature of 300 to 800° C.
Implementation Method 4
ageing-annealing the recrystallization-annealed copper alloy at a temperature of 300 to 600° C.
Data Source
AI summary
An inexpensive sheet material of a copper alloy has excellent bending workability and excellent stress corrosion cracking resistance while maintaining high strength. The sheet material is produced by a method including melting and casting raw materials of a copper alloy which has a chemical composition having 17 to 32 wt. % of zinc, 0.1 to 4.5 wt. % of tin, 0.01 to 2.0 wt. % of silicon, 0.01 to 5.0 wt. % of nickel, and the balance being copper and unavoidable impurities; hot-rolling the cast copper alloy at 900° C. to 400° C.; cooling the hot-rolled copper alloy at 1 to 15° C./min. from 400° C. to 300° C.; cold-rolling the cooled copper alloy; recrystallization-annealing the cold-rolled copper alloy at 300 to 800° C.; and then, ageing-annealing the recrystallization-annealed copper alloy at 300 to 600° C.