Multiscale Experimentation and Modeling of Localized Damage in Diffusion‐Bonded 316L Stainless Steel Structures

Herein, experimental and modeling tools are employed to understand the joint area for a diffusion‐bonded 316L stainless steel. Detailed microstructure characterizations by means of optical microscopy, electron backscatter diffraction, and energy‐dispersive X‐ray spectroscopy are coupled to in situ micromechanical testing and micro‐ and nano‐indentation to fully reveal the properties at the joint area. Crystal plasticity finite‐element modeling is performed utilizing the exact microstructure to understand the effect of individual slip systems on transgranular strain fields. It is revealed that the diffusion line is only marginally harder. The final failure of the sample occurred away from the joint area, and both the base metal and bond line, shows evidence of considerable twinning and plastic deformation by (dislocation) slip initiating at grain boundaries. Additional slip systems and slip bands form to propagate across all matrices, blocking further dislocations after the ultimate tensile strength point. The presence of flaws within the weldment is found to be negligible.