Dissimilar Metal Joint via Weld Contraction Sandwich
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Solution Overview
Problem
Existing dissimilar material joint structures, such as those in steam generators, face challenges in achieving sufficient joint strength between dissimilar metal materials like anti vibration bars and retaining bars, particularly when subjected to flow-induced vibrations, and require thermal treatment for welding, which is time-consuming.
Innovation Solution
A dissimilar material joint structure where the first member (anti vibration bar) is sandwiched between multiple second members (end caps) formed from the same material as the retaining bar, allowing for welding without thermal treatment, enhancing joint strength through weld material contraction and mating portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If dissimilar metal materials (anti vibration bar and retaining bar) are joined by welding, then joint strength is improved, but thermal treatment is required which increases manufacturing time and complexity
Solution Approach 1:
A transition piece made from a third metal material is introduced as an intermediary between the anti vibration bar (first metal material) and the retaining bar (second metal material). This transition piece serves as a mediator that enables joining of dissimilar metals without requiring thermal treatment, thus resolving the contradiction between achieving strong joints and reducing manufacturing time.
Solution Approach 2:
The joint structure employs a composite construction consisting of three different metal materials: the anti vibration bar, the transition piece, and the retaining bar. Each component is made from a specific metal material selected for its properties, creating a composite joint system that achieves both strength and ease of manufacture without thermal treatment requirements.
2Strength
If dissimilar metal materials are joined by welding, then joint strength is improved, but the complexity of the welding process increases due to thermal treatment requirements
Solution Approach 1:
The transition piece acts as an intermediary component that simplifies the welding process by eliminating the need for thermal treatment. By introducing this intermediate element made from a compatible metal material, the complex dissimilar metal welding is replaced with simpler like-metal or compatible metal welding operations.
Solution Approach 2:
The joint is segmented into three separate components (anti vibration bar, transition piece, retaining bar) rather than directly joining two dissimilar metals. This segmentation allows each component to be optimized for its specific function and material properties, reducing the overall complexity of the welding process.
3Ease of manufacture
If existing dissimilar material joint structures are used, then manufacturing is simplified, but joint strength is insufficient for preventing flow-induced vibrations
Solution Approach 1:
The invention uses a composite structure with three metal materials where the transition piece made from a third metal material provides the necessary mechanical strength to withstand flow-induced vibrations, while still maintaining ease of manufacture through straightforward welding connections without thermal treatment.
Solution Approach 2:
Each component in the joint structure is made from a specific metal material locally optimized for its function: the anti vibration bar from one metal material, the transition piece from a third metal material with appropriate mechanical properties, and the retaining bar from a second metal material. This local optimization of material properties achieves both strength and manufacturability.
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 eliminates the need for thermal treatment and significantly improves the joint strength between dissimilar metal materials, making the welding operation easier and more efficient.
Implementation Method 1
due to contraction of the weld material welding the respective second members, the first member is sandwiched between one of the second members and the other second member, whereby the first member and the second members are joined
Data Source
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AI summary
In a dissimilar material joint structure that joins together an anti vibration bar (first member) 14 and a end cap (second member) 15, which is a dissimilar metal material to the anti vibration bar 14, the anti vibration bar 14 is sandwiched by a plurality of end caps (second members) 151 and 152, and these respective end caps 151 and 152 are joined together by welding. Due to contraction of a weld material 153 welding the end caps 151 and 152, the anti vibration bar 14 is sandwiched between the end caps 151 and 152, whereby the anti vibration bar 14 and the end cap 15 are joined. Consequently, a thermal treatment for welding dissimilar metal materials is not required, and the welding operation can be carried out easily.