Electron Beam Weld Rastering for Microstructure Control
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Solution Overview
Problem
Existing electron beam welding methods face challenges in controlling microstructure formation due to high cooling rates, leading to inferior weld quality and increased costs from additional heat treatment processes, which are either slow or require costly hardware.
Innovation Solution
The method involves splitting the electron beam into a pre/post heat ring and a fusion spot, traversing them together along the weld path, with the fusion spot at the center of the ring, to control cooling rates and eliminate the need for pre-heating, using deflector coils for precise beam control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high traverse speed is used in EB welding to achieve high metal joining rate, then productivity is improved, but microstructure quality deteriorates due to high cooling rates forming sensitive phases
Solution Approach 1:
The electron beam is segmented into two distinct components: a preheat beam that prepares the material by raising its temperature, and a welding beam that performs the actual fusion. This segmentation allows each beam to be optimized for its specific function, enabling high traverse speeds while maintaining microstructure quality through controlled preheating.
Solution Approach 2:
The preheat beam performs preliminary action by heating the material before the welding beam arrives. This preliminary thermal preparation reduces the temperature gradient and cooling rate during welding, preventing the formation of sensitive microstructure phases even at high welding speeds.
2Manufacturing precision
If traverse speed is reduced to avoid fast-cooling microstructure formation, then microstructure quality is improved, but productivity deteriorates due to loss of high joining rate advantage
Solution Approach 1:
By separating the preheating function from the welding function into two distinct beams, the system can maintain high traverse speeds while ensuring proper thermal preparation. The preheat beam travels alongside the welding beam, continuously preparing the material without requiring speed reduction.
Solution Approach 2:
The preheat beam acts as an intermediary between the welding beam and the material, mediating the thermal interaction by first raising the material temperature. This intermediary action enables the welding beam to operate at high speeds while still achieving controlled cooling rates for quality microstructure formation.
3Manufacturing precision
If conventional arc welding is used instead of EB welding to avoid fast-cooling phases, then microstructure quality is improved, but weld geometry and material versatility deteriorate
Solution Approach 1:
The invention replaces the conventional arc welding mechanism with an electron beam-based system that incorporates a preheat beam. This substitution maintains the advantages of EB welding (precise geometry control, material versatility) while adding the microstructure quality control capability previously associated with slower arc welding processes.
4Manufacturing precision
If heat treatment processes are applied to raise ambient workpiece temperature, then microstructure quality is improved, but equipment cost and energy consumption deteriorate due to costly pre-heating hardware
Solution Approach 1:
The electron beam welder is made multi-functional by using its beam to perform both preheating and welding operations. This eliminates the need for separate preheating equipment such as ovens or resistance blankets, reducing capital costs while maintaining microstructure quality control.
Solution Approach 2:
The welding system performs its own preheating function through the preheat beam, making the process self-sufficient. This self-service capability eliminates dependence on external preheating equipment and reduces overall system complexity and cost.
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 achieves uniform weld quality with controlled crystallization, reduces processing time, and lowers equipment wear, maintaining high joining rates while avoiding costly pre-heating hardware.
Implementation Method 1
Electron beam welding is a known process... providing a high metal joining rate... The method involves guiding a first electron beam under formation of a welding seam along a joining area
Implementation Method 2
guiding a second electron beam before the first electron beam along the joining area for pre-heating the joining area
Implementation Method 3
guiding a first electron beam under formation of a welding seam along a joining area
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method of electron beam welding comprising splitting the output of an electron beam welder into two components, a pre/post heat ring and a fusion spot by rastering between the pre/post heat ring and a fusion spot, applying the two outputs to a workpiece that is to be welded, traversing the two outputs along the desired weld path, and wherein the fusion spot lies within the pre/post heat ring and travels in tandem with and inside the pre/post heat ring. The pre/post heat ring may be annular. The fusion spot may be located at the centre of the pre/post heat ring. The output of the electron beam welder may comprise 1 to 100,000 discrete points. The beams may be deflected using the EB welder deflector coils. The time the electron beam spends on each discrete point may be identical.