Copper Alloy Fastener Element With Dendrite Structure Against Season Cracking
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Solution Overview
Problem
Copper-zinc alloys used in fasteners face issues with season cracking due to residual stresses and corrosion, particularly when zinc content exceeds 10% by mass, leading to reduced strength and increased material costs when third elements are added to improve resistance.
Innovation Solution
A copper-zinc alloy with a dendrite structure and a β phase ratio of 10% or less, produced through specific annealing and casting processes, maintains improved season cracking resistance without increasing the β phase ratio, thereby enhancing cold workability and mold life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If zinc content is increased to improve strength and cold workability, then strength and uniform deformation amount are improved, but corrosion resistance deteriorates and season cracking occurs
Solution Approach 1:
The patent applies parameter changes by precisely controlling the zinc content within a specific range (10-38 mass%) and adjusting the ratio of beta phase (10-40%) to achieve optimal balance between strength and corrosion resistance. The invention also controls crystal grain structure through cold working to create a layered arrangement, which improves mechanical properties while maintaining corrosion resistance.
2Quantity of substance
If zinc content is increased to reduce material cost, then material cost is reduced, but season cracking resistance deteriorates
Solution Approach 1:
The patent resolves this contradiction by establishing a specific parameter range for zinc content (10-38 mass%) that maintains both cost-effectiveness and season cracking resistance. The invention achieves this by controlling the beta phase ratio and crystal grain structure, allowing higher zinc content without sacrificing reliability.
3Strength
If beta phase ratio is increased to improve strength, then strength is improved, but cold workability deteriorates and mold life shortens
Solution Approach 1:
The patent applies parameter changes by optimizing the beta phase ratio within a specific range (10-40%) rather than maximizing it. The invention balances strength and cold workability by controlling this phase ratio alongside crystal grain structure through cold working, achieving both improved strength and maintained manufacturability.
4Reliability
If third elements are added to improve season cracking resistance, then season cracking resistance is improved, but material cost increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the zinc content parameter within a specific range (10-38 mass%) and controlling the beta phase ratio, eliminating the need for expensive third elements. The invention achieves season cracking resistance through parameter optimization of the copper-zinc alloy system itself, maintaining cost-effectiveness.
5Reliability
If third elements are added to prevent season cracking, then season cracking resistance is improved, but cold workability deteriorates
Solution Approach 1:
The patent resolves this contradiction by controlling the zinc content (10-38 mass%) and beta phase ratio (10-40%) within specific ranges, achieving season cracking resistance without adding third elements that would harm cold workability. The invention maintains good cold workability while preventing season cracking through parameter optimization.
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 approach results in a copper alloy fastener element with improved season cracking resistance and industrial productivity, offering high utility value by maintaining a balance between strength and cost-effectiveness.
Implementation Method 1
a copper-zinc alloy with a dendrite structure maintaining a small β-phase ratio
Implementation Method 2
a dendrite structure
Implementation Method 3
produced through specific annealing and casting processes
Data Source
AI summary
Provided is a copper alloy fastener element which improves season cracking resistance by a means different from that of increasing a ratio of a β phase. The copper alloy fastener element includes a copper-zinc alloy as a base material, the base material having: an apparent zinc content of from 34 to 38%; a dendrite structure; and a β phase at a ratio of 10% or less.