Dissimilar Metal Member Interface Geometry for Crack-Free Deposition
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Solution Overview
Problem
Existing methods for manufacturing dissimilar metallic members using additive manufacturing techniques, such as laser metal deposition, face challenges with gaps and cracks at the interface, leading to reduced mechanical strength and reliability due to inadequate melting of base material and powder material at the side surfaces, and residual stress concentrations.
Innovation Solution
The method involves preparing a base member with stepwise stairs and using laser metal deposition to build up a shaped article with a cermet powder material, ensuring that at least one corner of each stair is within the laser spot diameter to ensure thorough melting and forming an interface with an angle of 70 degrees or more, reducing the risk of gaps and cracks by improving adhesion and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If additive manufacturing techniques are used to weld dissimilar metals, then the ability to manufacture complex shapes and repair molds is improved, but gaps and cracks occur at the interface reducing mechanical strength
Solution Approach 1:
The base material surface is pre-treated by machining to create a stair-shaped cross-sectional surface before additive manufacturing. This preliminary action ensures proper laser beam incidence angles and prevents gaps and cracks during the buildup process, thereby maintaining mechanical strength while enabling complex shape manufacturing.
Solution Approach 2:
The invention controls the angle of incidence of the laser beam by preparing the base material surface with specific geometric features (stair-shaped surface). By changing the surface geometry parameters, the laser beam can properly melt both base material and powder material at side surfaces, preventing interface defects and improving mechanical strength.
2Productivity
If laser metal deposition is used to build up material, then productivity and repair capability are improved, but inadequate melting at side surfaces causes gaps and cracks
Solution Approach 1:
The base material is pre-machined to create a stair-shaped surface with specific angles before the additive manufacturing process. This preliminary preparation ensures that the laser beam can properly access and melt side surfaces during buildup welding, eliminating gaps and cracks while maintaining high productivity.
Solution Approach 2:
The invention applies different surface geometries at different locations of the base material. The stair-shaped surface is created specifically at the interface region where additive manufacturing will occur, while other parts of the base material maintain their original geometry. This local modification ensures proper laser melting at the critical interface zone.
3Adaptability or versatility
If dissimilar metals are joined by additive manufacturing, then material selection flexibility is improved, but residual stress concentrations reduce reliability
Solution Approach 1:
The invention controls the geometric parameters of the interface region by creating a stair-shaped surface with specific angles. This parameter control ensures proper laser beam interaction and uniform melting, reducing residual stress concentrations and improving joint reliability while maintaining material selection flexibility.
Solution Approach 2:
The invention promotes homogeneous mixing of dissimilar metals at the interface by ensuring proper laser melting of both base material and powder material. The controlled surface geometry facilitates uniform material distribution and bonding, reducing heterogeneity-induced stress concentrations and improving overall joint reliability.
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 gaps and cracks, enhances the mechanical strength and reliability of dissimilar metallic members by ensuring thorough melting and improved adhesion between the base member and the shaped article, thereby increasing the durability of the mold components.
Implementation Method 1
a step of buildup-welding a shaped article on the base member by using an additive manufacturing method that supplies a powder material that is a second material that is different from the first material into a spot diameter of laser light while emitting the laser light
Implementation Method 2
ensuring that at least one corner of each stair is within the laser spot diameter to ensure thorough melting
Data Source
AI summary
A member includes a first metallic region made of a first material; a second metallic region made of a second material that is a different from the first material; and a mix region made of mixture of the first and second materials between the first and second metallic region. In a cross-sectional view, an interface between the first metallic region and the mix region is represented by a line having a first curved line protruding toward the first metallic region and a second curved line protruding toward the first metallic region, and an angle at a cross point of the first and second curved lines, the angle being made by a tangent line of the first curved line and a tangent line of the second curved line in a region of the first metallic region, is equal to or larger than 70 degrees and smaller than 180 degrees.