Press-Fit Joining Element for Low-Corrosion Steel-Aluminum Welding
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Solution Overview
Problem
Conventional methods for joining ferrous and non-ferrous metals, such as aluminum and steel, face challenges in reducing galvanic corrosion, which increases operational processes and costs due to exposed ferrous metal areas on the back surface of non-ferrous metals.
Innovation Solution
A manufacturing method involving a press fit of a ferrous metal joining element into a non-ferrous metal, where a part is exposed for welding while the remaining part is buried, using low-carbon steel with a carbon content of 0.4 mass % or less, and incorporating design features like parallel and inclined surfaces to enhance fit and reduce exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a joining element made of ferrous metal is plunged and pushed into a back surface of a non-ferrous metal material and welded to its surface, then the joining element can be securely attached to the mating member, but the exposed part of the joining element on the back surface causes galvanic corrosion between the non-ferrous metal material and the joining element
Solution Approach 1:
The harmful exposed part of the joining element that causes galvanic corrosion is extracted/removed from the system by ensuring it is completely buried within the non-ferrous metal material, with only the necessary welding surface exposed on the front side
Solution Approach 2:
The joining element is nested within the non-ferrous metal material, with the majority of its body embedded inside the material to prevent exposure and galvanic corrosion, while maintaining functional connectivity
2Object-affected harmful factors
If the joining element is completely buried in the non-ferrous metal material to prevent galvanic corrosion, then galvanic corrosion is reduced, but the welding connection to the mating member becomes difficult to establish
Solution Approach 1:
The joining element has different exposure conditions for different parts: the welding surface is locally exposed on the front side for easy welding connection, while the rest of the body is buried within the non-ferrous metal material to prevent galvanic corrosion
3Productivity
If conventional joining methods are used without special measures, then the manufacturing process is simple, but galvanic corrosion occurs between the non-ferrous metal material and the ferrous metal joining element
Solution Approach 1:
The joining element is pre-configured with appropriate dimensions and material properties (low carbon content) before installation, enabling it to be directly pressed and welded into the non-ferrous metal material without requiring additional anti-corrosion treatment steps
4Strength
If the joining element is made of high-carbon steel for strength, then the joining strength is improved, but the risk of cracking and hardening during welding increases
Solution Approach 1:
The material composition parameter of the joining element is changed by using low-carbon steel (carbon content 0.4 mass% or less) instead of high-carbon steel, which maintains adequate strength while significantly reducing the risk of welding-induced cracking and hardening
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 method reduces galvanic corrosion, enhances weld strength, and minimizes the risk of cracking and hardening, ensuring strong bonding between ferrous and non-ferrous metals while maintaining the non-ferrous metal's ductility and preventing excessive hardness.
Implementation Method 1
a press fit step of press-fitting the joining element made of ferrous metal into the predetermined surface of the non-ferrous metal material
Implementation Method 2
weld the joining element that penetrated the non-ferrous metal material to its surface to the mating member resistance spot welding
Implementation Method 3
a welding step of forming a melted portion between an exposed part of the joining element press-fitted into the non-ferrous metal material and the mating member
Data Source
AI summary
A manufacturing method for joined bodies that allows galvanic corrosion to be reduced is provided. The method is for manufacturing a joined body obtained by joining together a mating member made of ferrous metal and a non-ferrous metal material. The method includes: a press fit step of press-fitting a joining element made of ferrous metal into a predetermined surface of the non-ferrous metal material; and a welding step of forming a melted portion between an exposed portion of the joining element press-fitted into the non-ferrous metal material and the mating member. After the press fit step, a part of the joining element is exposed from the predetermined surface and the remaining part of the joining element is not exposed and is buried in the non-ferrous metal material. The remaining part of the joining element includes a lodging portion having a surface facing to the predetermined surface.