Method for manufacturing dissimilar material joint structure, and dissimilar material joint structure
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Solution Overview
Problem
The existing methods for joining aluminum or aluminum alloy materials with steel materials, such as those used in vehicle bodies, face challenges with adhesion strength due to high heat effects during welding, leading to reduced joint strength and increased blowholes, particularly when using arc welding or metal thermal spray coatings.
Innovation Solution
A method involving the formation of a low-temperature thermal spray coating on the aluminum or aluminum alloy material using metals like pure iron, stainless steel, or nickel alloys, followed by laser welding from the steel side, with controlled heat input to minimize fusion and prevent blowholes, ensuring a strong bond without melting the aluminum alloy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If arc welding with large heat effects (TIG, MIG, plasma welding) is used to join aluminum or aluminum alloy material with steel material, then the joining method can be implemented, but the adhesion strength of the metal coating to the steel is significantly reduced and the joint strength is lowered
Solution Approach 1:
The patent changes the welding parameters by using laser welding instead of arc welding, which provides more concentrated and controllable heat input. This allows the welding process to achieve adequate penetration while minimizing the overall heat affected zone, thereby preserving the adhesion strength of the metal coating to the steel substrate.
Solution Approach 2:
The patent replaces the mechanical arc welding system with a laser-based welding system. The laser provides a highly concentrated energy source that can be precisely controlled in terms of power, speed, and focal point, enabling better heat management and reduced thermal distortion compared to traditional arc welding methods.
2Ease of manufacture
If metal thermal spray coating is used to enable welding between aluminum or aluminum alloy material and steel material, then the joining can be performed, but large blowholes are easily generated in the weld metal and joint strength decreases
Solution Approach 1:
The patent optimizes the thermal spray coating parameters by using low-temperature thermal spray to form a coating with controlled thickness and composition. This coating serves as an effective transition layer that facilitates welding while minimizing the formation of blowholes, as the controlled coating structure allows for better gas evacuation during the welding process.
Solution Approach 2:
The patent uses a metal coating formed by low-temperature thermal spray as an intermediary layer between the aluminum or aluminum alloy material and the steel material. This intermediate coating layer acts as a buffer that improves weldability while controlling the formation of intermetallic compounds and reducing blowhole generation during laser welding.
3Strength
If high tensile strength steel material is used to reduce vehicle body weight and enhance collision safety, then the vehicle body weight is reduced and safety is enhanced, but the manufacturing cost increases and the joining complexity with aluminum materials increases
Solution Approach 1:
The patent employs a metal coating as an intermediary layer that simplifies the joining process between high tensile strength steel and aluminum or aluminum alloy materials. This coating layer acts as a compatible interface that reduces the complexity of direct dissimilar metal welding, enabling more straightforward manufacturing while maintaining the high strength requirements for collision safety.
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 a strong, lightweight joint with reduced blowholes and enhanced adhesion strength, suitable for high-strength steel and aluminum combinations, addressing the limitations of previous methods by maintaining the mechanical properties of both materials.
Implementation Method 1
forming a low-temperature thermal spray coating on at least a part of a surface of an aluminum or aluminum alloy material by low-temperature thermal spraying a metal powder
Implementation Method 2
joining the aluminum or aluminum alloy material and the steel material by a laser welding from a steel material side
Implementation Method 3
joining the aluminum or aluminum alloy material and the steel material by a laser welding from a steel material side
Data Source
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AI summary
Provided are: a method for manufacturing a dissimilar material joint structure; and a dissimilar material joint structure, wherein in dissimilar material joining between an aluminum or aluminum alloy material and a steel material, one-sided welding from the steel material side can be performed, and excellent joint strength with few blow holes can be achieved. The method comprises: a step for low-temperature spraying metal powder onto at least a portion of the surface of an aluminum or aluminum alloy material (2) to form a low-temperature sprayed coating (1); a step for superimposing the aluminum or aluminum alloy material (2) and a steel material (3) such that the low-temperature sprayed coating (1) and the steel material (3) face each other; and a step for joining the aluminum or aluminum alloy material (2) and the steel material (3) by laser welding from the steel material (3) side. The joining step is performed under welding conditions in which a weld metal (4), which is a molten portion, is formed in any of the steel material (3), the low-temperature sprayed coating (1), and the aluminum or aluminum alloy material (2).