Double-Wire Additive Manufacturing Process of Functionally Graded Material by Robotic Arc Welding

Area of Science:

• Materials Science and Engineering
• Metallurgy
• Additive Manufacturing

Background:

• SS316L requires enhanced durability and corrosion resistance for industrial use.
• Inconel 625 offers superior properties but at a higher cost.
• Functionally Graded Materials (FGMs) offer a potential solution for combining properties of dissimilar materials.

Purpose of the Study:

• To fabricate SS316L/Inconel 625 FGMs using a double-wire and double-pulse metal inert gas welding process.
• To analyze the effect of different gradient compositions (5% and 25% Inconel 625) on material properties.
• To evaluate the feasibility of FGMs for improving performance and reducing costs compared to single materials.

Main Methods:

• Fabrication of thin-walled SS316L/Inconel 625 FGMs via double-wire and double-pulse MIG welding.
• Microstructural and morphological analysis using energy dispersive spectrometer and electron backscattered diffraction.
• Mechanical property testing, including hardness and tensile strength measurements along the build direction.

Main Results:

• A consistent 5% Inconel 625 gradient resulted in a more stable deposition, higher efficiency, and improved material properties.
• Fractures were observed in the 75% SS316L region, specifically at the cellular dendrite boundaries.
• Hardness increased, while tensile strength decreased along the build direction, with the lowest strength in the 75% SS316L/25% Inconel 625 composition.

Conclusions:

• The double-wire and double-pulse MIG welding process is suitable for manufacturing gradient materials.
• Avoiding compositions close to 75% SS316L is recommended to prevent premature failure in dissimilar FGMs.
• The fabricated FGMs offer a cost-effective solution with improved mechanical properties compared to SS316L, extending service life.