Solid Phase Bonding Metal Edges Without Heat-Affected Zones
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Solution Overview
Problem
Flash butt welding creates heat-affected zones (HAZ) in metals, altering their microstructure and properties, which are undesirable and require additional processing steps to mitigate, increasing time, cost, and complexity.
Innovation Solution
A solid phase bonding process that heats metal edges to a temperature below the melting point and applies axial forces to form a bond without creating a heat-affected zone, using multiple upset stages to ensure a clean, uniform microstructure and strong bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If flash butt welding is used to join metal pieces, then a strong bond is formed, but a heat-affected zone is created that alters microstructure and requires additional processing
Solution Approach 1:
The invention changes the temperature parameter from above-melting (flash butt welding) to below-melting solid phase bonding. By maintaining temperatures in the solid phase range (0.35-0.95 of melting temperature), the process achieves strong bonding while avoiding the heat-affected zone that occurs when materials are heated to melting temperatures and then cooled, which creates microstructural alterations requiring additional annealing steps.
Solution Approach 2:
The invention replaces the thermal-melting mechanism of flash butt welding with a solid phase bonding mechanism that relies on mechanical upset and diffusion at solid state temperatures. Instead of melting and solidifying metal to create bonds, the process uses heated solid metal surfaces that are pressed together with upset force to create diffusion bonds, eliminating the harmful thermal cycle that creates heat-affected zones.
2Ease of manufacture
If traditional flash butt welding is used, then metal pieces are joined, but additional processing steps are required to treat the heat-affected zone
Solution Approach 1:
The invention extracts and eliminates the heat-affected zone formation from the joining process by using solid phase bonding temperatures below the melting point. By removing the melting and rapid cooling cycle that creates HAZ, the additional post-welding annealing or heat treatment steps become unnecessary, simplifying the overall manufacturing process while maintaining strong joint integrity.
Solution Approach 2:
The solid phase bonding process creates a continuous useful action where heating and upset bonding occur in a single integrated step without interruption for additional heat treatment. The bonding process itself produces the desired microstructure and mechanical properties, eliminating the need for separate annealing or heat treatment operations that would otherwise be required to restore material properties in the heat-affected zone.
3Manufacturing precision
If multiple upset stages are applied to ensure uniform microstructure, then bond quality improves, but process time increases
Solution Approach 1:
The invention uses periodic upset stages with intermediate cooling periods to achieve uniform microstructure. Rather than applying continuous upset force, the process applies upset in discrete periodic stages, allowing diffusion and bonding to occur during each stage while maintaining temperature control. This periodic action ensures thorough microstructure uniformity while minimizing total process time compared to continuous or excessive upset cycling.
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 process eliminates the formation of heat-affected zones, resulting in a strong, uniform solid phase bond with increased hardness and improved mechanical properties, suitable for joining various metals without the need for additional processing steps.
Implementation Method 1
heating the first and second edges to a temperature in the range of 0.35-0.95 of the melting temperature of the first and second metal pieces
Implementation Method 2
applying a first axial force to the first and second metal pieces to urge the first and second edges together, to upset the metal at the edge to edge contact and form a bond
Data Source
AI summary
A method of solid phase bonding metal pieces by securing a first and second metal pieces in edge to edge contact; subjecting the first and second metal pieces to a first upset comprising heating the first and second edges to a temperature in the range of 0.35-0.95 of the melting temperature of the first and second metal pieces and applying a first axil force to the first and second metal pieces to urge the first and second edges together, to upset the metal at the edge to edge contact and form a bond; and subjecting the bonded metal piece to a second upset comprising heating the bonded metal piece between secured locations to a temperature in the range of 0.35-0.95 of the melting temperature of the metal and applying a second axil force to the bonded metal piece to upset the bonded metal piece and form a solid phase bond.