Mitigation of micro-cracks in dissimilar welding of Inconel 718 and austenitic stainless steel

ABSTRACT

Intermetallic formation by solute segregation during dissimilar welding of Inconel 718 and SS316L stainless steel poses a severe challenge of solidification cracking in the welded structure. The minimisation of these intermetallic phases and, eventually, the solidification cracks through variation in welding speed is undertaken in the current study. With a reduction in welding speed, an improvement in the weld dilution level is observed along with a change in microstructural morphology from columnar to equiaxed dendrites. A reduction in solute segregation is evident with higher weld dilution level and equiaxed structure as compared with the columnar dendrites. The enrichment of Nb, Mo, and Ti is witnessed near micro-crack sites produced with a higher welding speed. X-ray diffraction (XRD) analysis confirmed the presence of various intermetallic phases and found to decrease with a reduction in the welding speed. With a reduction in welding speed, the tensile strength improved marginally, whereas a remarkable improvement in tensile ductility (∼ 90%) was found.

KEYWORDS:

• Inconel 718
• SS316L
• dissimilar welding
• micro-fissure
• intermetallic phases

Acknowledgements

The authors gratefully acknowledge the Department of Mechanical Engineering, Central Workshop, and Central Instrument Facility (CIF) of IIT Guwahati for providing financial support and experimental facilities to enable the present investigation.

Disclosure statement

No potential conflict of interest was reported by the author(s).