Dissimilar Metal Joint Geometry for Crack-Free Laser Deposition
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Solution Overview
Problem
Existing methods for manufacturing dissimilar metal members using additive manufacturing techniques, such as laser metal deposition, often result in gaps and cracks due to inadequate melting of metal at the interface between the base material and the deposited material, leading to weakened joint strength and potential wear or damage in mold components.
Innovation Solution
A method involving the preparation of a base member with stepwise stairs and the use of laser metal deposition to build up a shaped article using cermet powder, ensuring that at least one corner is within the spot diameter of the laser light to ensure thorough melting and bonding, thereby reducing the risk of gaps and cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additive manufacturing is used to build up high alloy material on base member, then wear resistance and strength of specific portions are improved, but gaps and cracks occur at the interface between dissimilar metals
Solution Approach 1:
The base member surface is pre-treated by shot blasting to increase roughness before additive manufacturing. This preliminary action enhances the mechanical interlocking between the base member and the built-up material, preventing gaps and improving joint strength without causing defects at the interface.
Solution Approach 2:
The invention uses dissimilar metal combination where a high alloy material (such as stainless steel or nickel-based alloy) is built up on a different base material (such as carbon steel). This composite structure provides both the cost-effectiveness of the base material and the superior wear resistance of the high alloy material, while controlled welding parameters ensure defect-free interfaces.
2Manufacturing precision
If laser light is emitted to melt powder material for additive manufacturing, then material bonding is achieved, but inadequate melting occurs at corners and side surfaces
Solution Approach 1:
The invention transitions from single-direction (top-down) laser irradiation to multi-directional irradiation by adding side surface heating. The laser light is emitted not only from above but also from the side to directly irradiate corner portions, ensuring complete melting and eliminating cold spots that would cause defects.
Solution Approach 2:
Different regions of the base member receive different heating treatments: the upper surface receives laser heating for material deposition, while corner and side surface regions receive additional direct laser irradiation to ensure complete melting. This localized quality control ensures uniform melting completeness throughout the interface without requiring excessive overall process complexity.
3Productivity
If powder material is supplied into laser spot for buildup welding, then material deposition is achieved, but gaps form between deposited material and base member
Solution Approach 1:
The invention merges the powder supply process with the laser irradiation process by positioning the powder supply nozzle within the laser spot area. This ensures that powder material is supplied directly to the molten pool zone, achieving both efficient deposition and continuous interface formation without gaps between the deposited material and base member.
Solution Approach 2:
The invention replaces mechanical bonding (reliance on cooling and solidification alone) with thermal bonding through controlled laser heating. By maintaining the powder material in a molten state through continuous laser irradiation and ensuring complete melting at the interface, the process achieves gap-free bonding without relying solely on mechanical interlocking from cooling contraction.
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 of dissimilar metal members, and improves the reliability of the joint interface, effectively addressing the limitations of previous methods by ensuring thorough melting and bonding of the materials.
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 is within the spot diameter of the laser light to ensure thorough melting and bonding
Data Source
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AI summary
Reliability of a member made of dissimilar metals is improved. 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 material from the first material; and a mix region made of mixture of the first material and the second material between the first metallic region and the second metallic region. In this case, 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 curved line and the second curved line, 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.