Role of intermetallics on fatigue behaviuor of stainless steel adhered by Sn

The fatigue property of 304 stainless steel (SS) adhered by Fe-Sn intermetallics was investigated. The microstructure of crack nucleation and crack propagation was observed, and the influence of Fe-Sn intermetallics on fatigue failure was analyzed. Fatigue tests at stress ratio of R = −1 were performed using a sine waveform at 20 Hz frequency under load control. In addition, the morphology and microfractography of the Fe-Sn intermetallics were examined under a scanning electron microscope. Results demonstrated that the adherence of the interfacial (Fe, Cr)Sn 2 layer reduced the fatigue life of the 304 SS substrates. The fatigue cracks also exhibited the intergranular fracture characteristics of the intermetallics. The brittle (Fe, Cr)Sn 2 intermetallics were apt to fatigue crack nucleation. The interfacial metallurgical bonding, which was caused by diffusion reaction between Fe and Sn atoms, led to crack propagation into the SS substrate.