Stainless Steel-Copper Cladding for Uniform Thin-Gauge Weld Strength

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Solution Overview

Problem

The existing clad materials with stainless steel and copper alloy layers exhibit variations in thickness, leading to decreased weld strength and mechanical strength variability when welded to other members, and are prone to tearing or pinholes during rolling.

Innovation Solution

A clad material with a stainless steel first layer, a copper or copper alloy second layer, and a stainless steel third layer, where the minimum thickness of each layer is set to 70% or more and less than 100% of the average thickness, ensuring uniformity and preventing excessively small thicknesses, and a manufacturing method involving clad rolling with a pressure-bonding load of 4.4 × 10^3 N/mm or more to maintain layer uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the minimum thickness of the stainless steel layers is excessively smaller than the target thickness, then the clad material can be manufactured with thinner overall dimensions, but the weld strength decreases and mechanical strength varies

Engineering Contradiction:
Improveoverall thicknessVSAvoidweld strength
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The patent applies a pressure-bonding load of 4.4 × 10^3 N/mm or more during clad rolling to achieve uniform thickness distribution in the stainless steel layers. This high pressure ensures that the minimum thickness remains 70% or more of the average thickness, preventing localized thinning that would compromise weld strength while allowing overall thickness reduction

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent establishes specific parameter ranges: minimum thickness of stainless steel layers should be 70% or more and less than 100% of the average thickness. By controlling this thickness ratio parameter, the invention achieves uniform layer distribution that maintains weld strength while enabling thinner overall clad material dimensions

Inventive Principle:
Principle #35Parameter changes

2Volume of moving object

If the minimum thickness of the stainless steel layers is excessively smaller than the target thickness, then the clad material can be manufactured with thinner overall dimensions, but the mechanical strength varies

Engineering Contradiction:
Improveoverall thicknessVSAvoidmechanical strength uniformity
Core Design Contradiction:
Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies a pressure-bonding load of 4.4 × 10^3 N/mm or more during clad rolling to achieve uniform thickness distribution in the stainless steel layers. This high pressure ensures that the minimum thickness remains 70% or more of the average thickness, preventing localized thinning that would compromise weld strength while allowing overall thickness reduction

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent establishes specific parameter ranges: minimum thickness of stainless steel layers should be 70% or more and less than 100% of the average thickness. By controlling this thickness ratio parameter, the invention achieves uniform layer distribution that maintains weld strength while enabling thinner overall clad material dimensions

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If the clad material is rolled with insufficient pressure-bonding load, then the manufacturing process is easier and less energy-consuming, but tearing or pinholes occur and the copper layer is uncovered

Engineering Contradiction:
Improverolling processVSAvoidlayer integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies a pressure-bonding load of 4.4 × 10^3 N/mm or more during clad rolling to achieve uniform thickness distribution in the stainless steel layers. This high pressure ensures that the minimum thickness remains 70% or more of the average thickness, preventing localized thinning that would compromise weld strength while allowing overall thickness reduction

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent performs preliminary thickness calculation and planning before the rolling process, determining the required pressure-bonding load based on the desired minimum thickness (70% or more of average thickness). This preliminary action ensures that sufficient pressure is applied to prevent tearing and pinhole formation while avoiding excessive pressure that would cause copper layer exposure

Inventive Principle:
Principle #10Preliminary action

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

This configuration significantly reduces the occurrence of decreased weld strength and mechanical strength variations, ensuring consistent characteristics and preventing uncovering of the copper layer due to tearing or pinholes, while maintaining mechanical strength, corrosion resistance, and conductivity.

Implementation Method 1

a first metal plate made of stainless steel, a second metal plate made of Cu or a Cu alloy, and a third metal plate made of stainless steel in this order, and clad rolling is performed

Methodology Applied
Scientific EffectDiffusion bonding: Diffusion Welding

Data Source

PatentEP3666441B1Cladding material and production method of cladding material
Publication Date: 2023.08.09 PROTERIAL LTD
  • EP3666441B1 patent drawingFigure 1~2
  • EP3666441B1 patent drawingFigure 3
  • EP3666441B1 patent drawingFigure 4

AI summary

A clad material (30) includes a first layer (31) made of stainless steel, a second layer (32) made of Cu or a Cu alloy and roll-bonded to the first layer, and a third layer (33) made of stainless steel and roll-bonded to a side of the second layer opposite to the first layer. The clad material has an overall thickness of 1 mm or less, and in a cross-sectional view along a stacking direction, a minimum thickness of the first layer in the stacking direction and a minimum thickness of the third layer in the stacking direction are 70% or more and less than 100% of an average thickness of the first layer in the stacking direction and an average thickness of the third layer in the stacking direction, respectively.