High-Strength Ductility Joining of Multicomponent Alloy to 304 Stainless Steel Using Laser Welding Technique

Area of Science:

• Materials Science and Engineering
• Metallurgy
• Additive Manufacturing

Background:

• Dissimilar laser welding of advanced alloys is crucial for developing novel structural materials.
• Understanding microstructural evolution and mechanical property correlations in laser-welded joints is essential for optimizing performance.
• High-entropy alloys (HEAs) and other multicomponent alloys offer unique properties but require careful joining techniques.

Purpose of the Study:

• To investigate the microstructural characteristics and mechanical properties of dissimilar laser welded joints between multicomponent alloys (CoCrFeNi, CoCrNi, CoNiV) and 304 stainless steel (304ss).
• To compare the effects of different multicomponent alloy compositions on the quality and performance of laser welded joints.
• To identify the optimal alloy combination and welding parameters for achieving superior mechanical properties in dissimilar joints.

Main Methods:

• Laser welding was employed to join CoCrFeNi, CoCrNi, and CoNiV alloys with 304ss.
• Microstructural analysis was performed using techniques to examine grain structure, phase distribution, and element segregation.
• Mechanical testing, including tensile tests, was conducted to evaluate the yield strength, ultimate tensile strength, and elongation of the welded joints.

Main Results:

• All dissimilar laser welded joints were defect-free with a homogeneous face-centered cubic (fcc) single-phase fusion zone and narrow element gradients.
• Equiaxed grains formed on the multicomponent alloy side, while coarse columnar grains, exhibiting preferential <001> growth, appeared on the 304ss side.
• Fracture occurred in the fusion zone due to reduced strength, except for the CoNiV/304ss joint, which exhibited a unique lamellar structure and achieved a yield strength of 338 MPa, ultimate tensile strength of 686 MPa, and elongation of 28.9%.

Conclusions:

• Laser welding of CoNiV alloy to 304ss results in a high strength-ductile synergy, outperforming other tested combinations.
• The unique fracture surface morphology in the CoNiV/304ss joint is linked to V-enriched regions, contributing to its superior mechanical performance.
• The CoNiV/304ss laser welded joint demonstrates significant potential as a structural material due to its excellent mechanical properties.