Copper Alloy Welding Wire Coating to Prevent Cracking
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Solution Overview
Problem
Copper cracking in electric arc welding occurs due to the migration of pure copper particles into the grain boundaries of the weld metal, leading to cracking and embrittlement, which is exacerbated by the reuse of granular flux and requires costly and time-consuming maintenance or the use of new flux and equipment refurbishment.
Innovation Solution
An electric arc welding wire with an outer conductive layer composed of a copper alloy (60-90% copper and 10-40% nickel, zinc, chromium, cadmium, or tin) that reduces flaking and migration of copper particles into the weld metal, maintaining effective electrical conductivity while minimizing copper cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pure copper is used as the outer layer of welding wire, then electrical conductivity is improved, but copper particles migrate into weld metal causing copper cracking
Solution Approach 1:
The patent applies composite materials by creating a multi-layer coating system consisting of a copper alloy layer (containing copper and at least one of nickel, zinc, chromium, cadmium, or tin) over the welding wire substrate. This composite structure combines the electrical conductivity benefits of copper with the cracking-resistant properties of alloying elements, preventing copper particle migration while maintaining effective current conduction during the welding process.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical composition of the outer layer from pure copper to a copper alloy with specific compositional ranges (copper: 60-90%, nickel: 0-40%, zinc: 0-40%, chromium: 0-40%, cadmium: 0-40%, tin: 0-40%). This compositional parameter change fundamentally alters the material properties, increasing surface tension and melting point while maintaining adequate conductivity, thereby preventing capillary migration of molten copper into weld grain boundaries.
2Loss of substance
If granular flux is reused to reduce waste, then cost is reduced, but copper particles accumulate in flux increasing copper cracking
Solution Approach 1:
The patent converts the harmful effect of flux reuse (copper particle accumulation) into a beneficial outcome by using a copper alloy coating that prevents copper cracking even when particles are present. The alloying elements modify the behavior of copper particles in the molten slag, preventing their migration into weld metal grain boundaries. This allows flux to be reused multiple times without the detrimental accumulation effect, transforming the previously harmful reuse scenario into a beneficial cost-saving practice.
3Object-affected harmful factors
If equipment is refurbished frequently to prevent copper flaking, then copper cracking is reduced, but productivity decreases and cost increases
Solution Approach 1:
The patent applies preliminary action by incorporating alloying elements (nickel, zinc, chromium, cadmium, or tin) into the copper coating during the manufacturing process, before the wire reaches the welding operation. This preliminary compositional modification creates inherent resistance to copper flaking and particle migration, eliminating the need for frequent equipment refurbishment and maintenance during welding operations, thereby sustaining high productivity without interruption.
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 copper alloy layer significantly reduces copper cracking by increasing surface tension and preventing particle migration into grain boundaries, eliminating the need for frequent maintenance and reducing waste, while maintaining electrical conductivity.
Implementation Method 1
The copper alloy apparently has higher surface tension and cannot migrate into the grain boundaries in the solidified weld metal by capillary action or otherwise.
Implementation Method 2
The resistivity of copper is quite low so the wire passing through the contact tip of the welding torch receives current from the contact tip without large heat loss in the torch itself and without arcing between the wire and the contact tip.
Implementation Method 3
The bead metal cools and solidifies at approximately 2800° F.; however, the copper in the molten slag remains molten and migrates through the slag to the surface of the solidified weld bead.
Implementation Method 4
The copper alloy apparently has higher surface tension and cannot migrate into the grain boundaries in the solidified weld metal by capillary action or otherwise.
Data Source
AI summary
An electric arc welding wire having an outer cylindrical surface and an electrically conductive layer on the surface wherein the layer comprises an alloy of copper with the copper content being about 60% to about 90% by weight of said alloy. Furthermore, the layer can be made thin with a thickness of less than about 0.50 microns while using essentially pure copper.