Cu-Ti Alloy Sheet Fatigue Resistance via Precipitate Control
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Solution Overview
Problem
Cu-Ti based copper alloys face challenges in enhancing fatigue resistance while maintaining strength, bending workability, and stress relaxation resistance, as the formation of grain boundary reaction type precipitates weakens the material and hinders these properties.
Innovation Solution
A Cu-Ti based copper alloy sheet with a specific composition and processing method, including a heat treatment temperature range of 550 to 730°C after solution treatment, to suppress the formation of grain boundary reaction type precipitates, achieving a metallic texture with controlled precipitate sizes and crystal grain diameters, which enhances fatigue resistance and maintains strength and bending workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength of Cu-Ti based copper alloy is enhanced by forming a modulated structure, then the strength increases, but the fatigue resistance and bending workability deteriorate due to the formation of grain boundary reaction type precipitates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Ti content within 2.0-5.0% and implementing specific heat treatment parameters (solution treatment at 750-950°C followed by aging at 300-450°C for 1-24 hours). These parameter optimizations suppress the formation of harmful grain boundary reaction type precipitates while maintaining the modulated structure for strength, thereby resolving the contradiction between strength enhancement and fatigue resistance
Solution Approach 2:
The patent creates a composite microstructure consisting of a Cu matrix with dispersed Ti precipitates and a modulated structure. This composite approach allows the material to simultaneously achieve high strength from the modulated structure and good fatigue resistance from the controlled precipitate distribution, eliminating the trade-off between these properties
2Strength
If the strength of Cu-Ti based copper alloy is enhanced by increasing Ti content, then the strength increases, but the bending workability deteriorates
Solution Approach 1:
The patent optimizes the Ti content parameter within the specific range of 2.0-5.0% and combines it with controlled heat treatment parameters. This parameter optimization ensures sufficient strength while preventing excessive Ti precipitation that would harm bending workability, achieving both high strength and good formability
3Strength
If the modulated structure is formed to harden the material, then the strength increases conspicuously, but the fatigue resistance and bending workability are reduced
Solution Approach 1:
The patent fine-tunes the heat treatment parameters including solution treatment temperature (750-950°C), aging temperature (300-450°C), and aging time (1-24 hours). These parameter changes optimize the modulated structure formation while suppressing harmful precipitate formation, thereby achieving high strength without sacrificing fatigue resistance
Solution Approach 2:
The patent creates a composite microstructure with Cu matrix, Ti precipitates, and modulated structure. This composite design allows the modulated structure to provide strength while the controlled precipitate distribution maintains fatigue resistance, resolving the contradiction between hardening and fatigue performance
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 method results in a Cu-Ti based copper alloy sheet with improved fatigue resistance, strength, bending workability, and stress relaxation resistance, suitable for electric current carrying components, and supports downsizing and thin-wall processing of electrical components.
Implementation Method 1
suppress the formation of grain boundary reaction type precipitates
Implementation Method 2
heat treatment temperature range of 550 to 730°C after solution treatment
Implementation Method 3
heat treatment with a heat pattern including a solution treatment at from 750 to 950°C, holding at a temperature ranging from 550 to 730°C
Data Source
Figure 1~2
Figure 3
AI summary
In a Cu-Ti based copper alloy sheet material, the fatigue resistance is improved while keeping strength, bending workability, and stress relaxation resistance good. Disclosed is a copper alloy sheet material including a composition containing from 2.0 to 5.0% of Ti, from 0 to 1.5% of Ni, from 0 to 1.0% of Co, from 0 to 0.5% of Fe, from 0 to 1.2% of Sn, from 0 to 2.0% of Zn, from 0 to 1.0% of Mg, from 0 to 1.0% of Zr, from 0 to 1.0% of Al, from 0 to 1.0% of Si, from 0 to 0.1% of P, from 0 to 0.05% of B, from 0 to 1.0% of Cr, from 0 to 1.0% of Mn, and from 0 to 1.0% of V in terms of % by mass, with the balance substantially being Cu, wherein the copper alloy sheet material has a metallic texture in which a cross section thereof perpendicular to the sheet thickness direction, a maximum width of a precipitate of grain boundary reaction type is not more than 500 nm, and a density of a granular precipitate having a diameter of 100 nm or more is not more than 105 number/mm2.