Additive Manufacturing of SS316L/IN718 Bimetallic Structure via Laser Powder Bed Fusion

Area of Science:

• Materials Science
• Metallurgy
• Additive Manufacturing

Background:

• Laser powder bed fusion (LPBF) is a key additive manufacturing (AM) technology for complex components.
• Fabricating dissimilar metal structures presents challenges in achieving crack-free parts and controlled microstructures.

Purpose of the Study:

• To report the successful crack-free fabrication of SS316L/IN718 bimetallic structures using LPBF.
• To investigate the compositional redistribution, phase transformations, microstructural development, and nanohardness variations within the bimetallic structure.
• To quantitatively analyze constituent intermixing using thermo-kinetic principles.

Main Methods:

• Laser powder bed fusion (LPBF) was employed for additive manufacturing.
• Thermo-kinetic coefficients of mass transport were used to estimate constituent intermixing.
• Diffusivity of Nickel (Ni) in the austenitic Fe-Ni system was used for comparison.

Main Results:

• Achieved crack-free fabrication of SS316L/IN718 bimetallic structures.
• Observed significant compositional redistribution and phase transformations.
• Documented microstructural development and corresponding nanohardness variations across the interface.
• Quantified intermixing and compared it with diffusion data.

Conclusions:

• LPBF enables the production of crack-free SS316L/IN718 bimetallic components.
• Understanding intermixing and microstructural evolution is crucial for controlling properties in AM dissimilar alloys.
• The study provides insights into the material science governing the fabrication of these advanced structures.