Aluminum Alloy Wire Rod Yield Strength Ratio

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Solution Overview

Problem

Aluminum alloy wire rods used in electric wiring structures face challenges in achieving a balance between tensile strength, elongation, and conductivity, especially when used as extra fine wires with diameters less than or equal to 0.5 mm, due to limitations in yield strength and durability.

Innovation Solution

An aluminum alloy wire rod composition comprising Mg, Si, Fe, and other elements, with controlled manufacturing processes including melting, casting, hot working, and heat treatments, to produce solute atom clusters that enhance tensile strength, elongation, and conductivity while maintaining a low yield strength to tensile strength ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If alloying elements are added to increase tensile strength, then tensile strength is improved, but conductivity decreases due to solid solution phenomenon and intermetallic compound formation

Engineering Contradiction:
Improvetensile strengthVSAvoidconductivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the composition ranges of alloying elements (Mg: 0.03-1.0 mass%, Si: 0.03-1.0 mass%, Ti: 0.003-0.03 mass%, B: 0.003-0.03 mass%) and implementing specific heat treatment parameters (solution treatment at 400-600°C for 5-120 minutes, aging at 100-200°C for 5-120 minutes) to optimize the balance between tensile strength and conductivity, achieving tensile strength ≥200 MPa while maintaining conductivity ≥45% IACS

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite microstructure consisting of aluminum matrix with controlled distribution of intermetallic compounds (Al3Ti, AlB12, Mg2Si) through specific alloying and heat treatment, where the composite structure provides both mechanical strength from the precipitates and electrical conductivity from the aluminum matrix

Inventive Principle:
Principle #40Composite materials

2Strength

If solution heat treatment and aging treatment are applied to increase strength, then tensile strength is improved, but yield strength increases causing large deformation force required for plastic deformation

Engineering Contradiction:
Improvetensile strengthVSAvoidease of routing and handling
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent optimizes the yield strength to tensile strength ratio by controlling the aging treatment parameters (temperature: 100-200°C, time: 5-120 minutes) to achieve a ratio ≤0.7, which allows the wire to maintain high tensile strength (≥200 MPa) while having sufficiently low yield strength for easy routing and handling in wire harness manufacturing

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies partial aging treatment to achieve the desired balance between strength and deformability, avoiding excessive aging that would maximize strength but make the wire too rigid for handling, thus achieving optimal performance for the specific application requirements

Inventive Principle:
Principle #16Partial or excessive action

3Strength

If alloying elements are added to achieve high tensile strength, then tensile strength is improved, but elongation decreases due to excessive intermetallic compounds

Engineering Contradiction:
Improvetensile strengthVSAvoidelongation
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent controls the elongation by limiting the total content of alloying elements and optimizing the ratio between them, specifically maintaining Mg and Si within 0.03-1.0 mass% each, which prevents excessive intermetallic compound formation and ensures elongation ≥15% while achieving tensile strength ≥200 MPa

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates local quality differences by controlling the distribution and size of intermetallic compounds through specific heat treatment, where fine and uniformly distributed precipitates provide strength without creating stress concentration points that would reduce elongation

Inventive Principle:
Principle #3Local quality

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 achieves a balance of high tensile strength, sufficient elongation, and good conductivity in aluminum alloy wire rods, enabling efficient routing and handling, even in fine wire diameters, and improves work efficiency in applications like automotive and industrial robotics.

Implementation Method 1

a conductivity may decrease due to a solid solution phenomenon of the additive elements into aluminum

Methodology Applied
Scientific EffectSolid solution phenomenon: Solid Solution Strengthening

Implementation Method 2

the strength can be increased by applying a solution heat treatment and an aging treatment

Methodology Applied
Scientific EffectPrecipitation hardening: Precipitation Hardening

Implementation Method 3

the strength can be increased by applying a solution heat treatment and an aging treatment

Methodology Applied
Scientific EffectSolution heat treatment: Heat Treatment

Implementation Method 4

the strength can be increased by applying a solution heat treatment and an aging treatment

Methodology Applied
Scientific EffectAging treatment: Annealing

Data Source

PatentEP3115473B1Aluminum alloy wire, aluminum alloy strand wire, coated electric wire, wire harness, process for producing aluminum alloy wire, and method for examining aluminum alloy wire
Publication Date: 2020.07.15 FURUKAWA ELECTRIC CO LTD
  • EP3115473B1 patent drawingFigure 1
  • EP3115473B1 patent drawing

AI summary

Provided is an aluminum alloy wire rod that has a low 0.2% yield strength (YS) to tensile strength (TS) while ensuring a good balance between tensile strength, elongation and conductivity. An aluminum alloy wire rod of the present invention has a composition comprising Mg: 0.10-1.0 mass%, Si: 0.10-1.20 mass%, Fe: 0.01-1.40 mass%, Ti: 0.000-0.100 mass%, B: 0.000-0.030 mass%, Cu: 0.00-1.00 mass%, Ag: 0.00-0.50 mass%, Au: 0.00-0.50 mass%, Mn: 0.00-1.00 mass%, Cr: 0.00-1.00 mass%, Zr: 0.00-0.50 mass%, Hf: 0.00-0.50 mass%, V: 0.00-0.50 mass%, Sc: 0.00-0.50 mass%, Co: 0.00-0.50 mass%, Ni: 0.00-0.50 mass%, and the balance: Al and incidental impurities, Mg/Si mass ratio being 0.4 to 0.8. The aluminum alloy wire rod has a tensile strength of 200 MPa or above, an elongation of 13% or above, a conductivity of 47% IACS, and a ratio (YS/TS) of 0.2% yield strength (YS) to the tensile strength (TS) of 0.7 or less.