Unmixing behaviour in dissimilar laser welds for duplex and austenitic stainless steels

ABSTRACT

Metallurgical characteristics of single-mode laser dissimilar welds between super duplex (UNS S32750) and austenitic (type 316L) stainless steels is the existence of an unmixed zone that originates from each base metal. It was confirmed that the unmixed zone that flowed out from the 316L had the microstructural morphology of primary austenite with secondary δ-ferrite solidification mode, while the morphology of a δ-ferrite single phase solidification mode was observed within the unmixed zone that flowed out from the S32750. Furthermore, it could be speculated that each unmixed zone that flowed out from 316L and S32750 coexisted independently in terms of crystallographic aspect (orientation distribution function and predominant orientation relationship) analysed by electron backscatter diffraction.

KEYWORDS:

• Single-mode fibre laser
• dissimilar welding
• super duplex stainless steel
• austenitic stainless steel
• unmixed zone

Acknowledgements

The authors would like to deeply thank Dr Su-Jin Lee of Korea Institute of Machinery and Materials, Republic of Korea for her help with welding experiment.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Project NK214T of the Korea Institute of Machinery and Materials, Republic of Korea.