Predicting the fracture behavior of 304 stainless steel thin sheet in the micro scale

The size effect in microscale occurs due to the presence of a limited number of grains in deformation area and affects the mechanical behavior of the material. Based on this, describing the material behavior in the micro scale requires new relations and theories. In this article, the fracture behavior of 304 stainless steel thin sheet was tested by performing a uniaxial tensile test on the specimens with different thicknesses and grain sizes in the micro scale. The results showed that the fracture strain of different specimens in the micro scale decreases with decreasing thickness or increasing the grain size of the sheet. In order to consider the interactive effect of sheet thickness and grain size, the aspect ratio parameter was defined as the ratio of thickness to the average grain size of the sheet. Based on this, Ayada phenomenological ductile fracture criterion was modified by considering the size effect in the micro scale. Predicting the fracture locus using the modified criterion is in accordance with the fracture strain of different specimens in the micro scale, and this criterion can predict the fracture strain of different specimens with a maximum error of 4.4%. Based on the obtained results, it was found that the proposed fracture criterion can be used to predict fracture in the micro scale processes.