Design of electron beam welded joints between stainless steel and Co-based superalloy: Revealing an incomplete γ → ε transformation mechanism

This study proposes a novel approach to electron beam welding of AISI 410L ferritic stainless steel and NS163 Co-based superalloy, exploring the mechanism of compositional influence on the γ → ε martensite transformation during rapid solidification. Results show that the enhancement of Co content reduces stacking fault energy from 34.2 to 15.0 mJ/m 2 , increases the number of internal defects and greatly contributes to the nucleation of ε-hcp martensite. Nanoindentation confirms that compressive residual stress facilitates this transformation, with stress values decreasing from approximately 1153 MPa to 414 MPa as the weld depth increases. Furthermore, the elevated fraction of ε-hcp endows the joint with remarkable strength and strain-hardening capability. These findings provide new insights into the design of welding joints for brush seals in practical manufacturing.