Font Size: 

Diffusion bonding has been gaining greater attention in the fabrication of
bonded joints of similar and dissimilar of austenitic stainless steel in nuclear and
chemical industries, particularly in Micro Chemo Mechanical Systems. In situ
observation of interfacial crack initiation and propagation was carried out on
316LSS vacuum diffusion bonded joints to investigate the microstructure
evolution and effect of micro-voids on interfacial failure mechanism. The results
showed that the most likely sites for cracks initiation are grain boundaries. The
favorable grain boundaries containing cracks are oriented at 0º~20º to the loading
axis. Intergranular cracks play a dominant role in interfacial failure. Micro-voids
do not link up each other until the load is increased to 352MPa (63%σb). For
316LSS diffusion bonded joints, lots of experimental observations showed that
interfacial failure depends mainly on microstructures of joints instead of
micro-voids left on interface. This information may provide us an important
insight to improve microstructures of joints after diffusion bonding.