Dendrite-Structured Copper Fastener Alloy for Season Cracking
Find Innovative SolutionsGenerate Solutions
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, which compromises strength and increases material costs, while increasing the β phase ratio improves strength but lowers cold workability and mold life.
Innovation Solution
A copper-zinc alloy with a dendrite structure and a β phase ratio between 2 to 10% is developed, produced through specific annealing and casting processes, maintaining a zinc content between 34 to 38% by mass, to enhance season cracking resistance without adversely affecting 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 season cracking resistance deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters by adding third elements (Al, Si, Mn, Ni, Fe) in controlled amounts (0.01-5.0 wt% each) to the copper-zinc alloy, modifying the alloy's properties to achieve both high strength and season cracking resistance simultaneously
Solution Approach 2:
The invention creates a composite alloy system by combining copper, zinc, and multiple third elements (Al, Si, Mn, Ni, Fe) to form a multi-element alloy that exhibits both high strength and resistance to season cracking, overcoming the limitations of binary copper-zinc alloys
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 invention optimizes the compositional parameters by precisely controlling the content of third elements (0.01-5.0 wt% each) to achieve the desired balance between cost-effectiveness (using affordable zinc) and season cracking resistance
3Strength
If ratio of β phase is increased to improve strength, then strength is improved, but cold workability and mold life deteriorate
Solution Approach 1:
The invention changes the microstructural parameters by controlling the β phase ratio to 10-50% through compositional adjustment with third elements, achieving an optimal balance between strength and cold workability
4Strength
If ratio of β phase is increased to improve strength, then strength is improved, but mold life deteriorates
Solution Approach 1:
The invention optimizes the β phase ratio parameter to 10-50% through compositional control, achieving sufficient strength while preventing excessive wear that would reduce mold life
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 improves season cracking resistance and extends mold life by maintaining a small β phase ratio, reducing material costs, and enhancing industrial productivity with improved industrial utility value.
Implementation Method 1
a two-phase structure of an α phase and a β phase, wherein a ratio of the β phase in the copper-zinc alloy is controlled to be greater than 10% and less than 40%, and wherein crystal grains of the α phase and the β phase are crushed into a flat shape by cold working
Implementation Method 2
a heat treatment is carried out at a temperature of from 400 to 700 °C in order to adjust the ratio of the β phase
Implementation Method 3
crystal grains of the α phase and the β phase are crushed into a flat shape by cold working so that the crystal grains are arranged in the form of layer
Implementation Method 4
Zinc has an effect of increasing strength, hardness and uniform deformation amount of the copper alloy by solid solution
Data Source
Figure 1
Figure 2
Figure 3
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.