Friction Stir Welding Root Support via Fusion Pre-weld
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Friction Stir Welding (FSW) for pipeline construction faces challenges due to the need for a backing support, which can lead to root defects and is impractical in field applications, especially with pipe misalignment and variations in diameter and thickness.
Innovation Solution
A method combining a fusion root weld with a friction stir weld, where the fusion root weld provides the necessary support for the FSW process without the need for a backing support, allowing for a strong and defect-free butt weld in structural steel components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If friction stir welding is used for pipeline construction, then welding speed and productivity are improved, but the need for backing support causes root defects and increases device complexity
Solution Approach 1:
The invention extracts and eliminates the backing support from the FSW process by performing a fusion weld first to create a solid root weld that provides the necessary support structure. This removes the complex backing support device while maintaining the productivity benefits of FSW.
Solution Approach 2:
The fusion root weld is performed as a preliminary action before the friction stir weld. This preliminary weld creates a strong foundation that eliminates the need for backing support during the subsequent FSW operation, resolving the device complexity issue while preserving productivity gains.
2Strength
If backing support is used during friction stir welding, then weld support is improved, but root defects increase and manufacturing precision deteriorates
Solution Approach 1:
The invention converts the potential harm of backing support-induced root defects into a benefit by using the fusion root weld as the support structure. The fusion weld, which would normally be a separate operation, becomes the foundation that supports the FSW process, eliminating root defects while maintaining weld strength.
3Device complexity
If friction stir welding is used without backing support, then device complexity is reduced, but the root area cannot support the down forces during welding
Solution Approach 1:
The fusion root weld is performed as a preliminary action to create a strong root weld that can support the down forces during the subsequent friction stir welding operation. This preliminary strengthening of the root area eliminates the need for backing support while maintaining the necessary force support capacity.
4Strength
If multiple fusion welding passes are used for thick pipes, then weld strength is improved, but welding time and loss of time increase
Solution Approach 1:
The invention merges the root weld operation with the friction stir welding operation. Instead of performing multiple separate fusion welding passes to achieve complete penetration and strength, the fusion root weld combined with FSW achieves the same structural integrity in a single integrated operation, dramatically reducing welding time while maintaining weld strength.
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 approach enables the formation of strong butt welds in structural steel components without the requirement for a backing support, reducing the likelihood of root defects and accommodating geometric misalignments, thus enhancing the efficiency and reliability of the welding process.
Implementation Method 1
Arc or fusion welding involves melting of the materials being welded to create the joint
Implementation Method 2
fusion welding the beveled faying surfaces of one side of the components under conditions sufficient to form a fusion root weld
Implementation Method 3
Friction Stir Welding (FSW) is a solid state joining technique that uses a rotating (spinning) tool to stir metal together to form a joint or weld. The heat generated during FSW softens the material adjacent to the tool and reduces its strength
Implementation Method 4
This softening (which extends a few millimeters from the tool) is necessary to plasticize the material and allow it to be stirred
Implementation Method 5
A translational force(s) is applied roughly parallel to the surfaces of the pieces being welded, this force being used to translate the tool along the weld joint
Data Source
AI summary
Provided are butt welds and methods of making such butt welds using a combination of fusion root welding and friction stir welding to yield welds with decreased propensity for dropout during friction stir welding without the need for a back-up support plate. In one form of the present disclosure, the butt weld includes: two or more abutting structural steel components beveled on faying surfaces on one side of the components to form a suitably shaped fusion root weld groove and unbeveled on faying surfaces on the opposite side of the components and interconnected with a first fusion root weld on the beveled side of the components and a second friction stir weld on the unbeveled side of the components, wherein the first fusion root weld has a width ranging from 7 mm to 30 mm, a penetration depth ranging from 2 mm to 20 mm, and an overfill ranging from 2 mm to 5 mm, and wherein the stir zone of the second friction stir weld penetrates the first fusion root weld. The butt welds and methods of making find application in joining linepipe for oil and gas production.