Failure analysis of AISI 430 stainless steel sheet under stretching and bending conditions

Ferritic stainless steels have been widely used to substitute austenitic steels because of their lower cost and higher deep drawing capacity. However, failures, such as shear fracture, have been observed in parts with small radii during the drawing process in applications where both bending and stretching occurs. Conventional techniques, such as failure criterion consideration, finite element method, and forming limit diagram, are unable to predict this type of fracture, which has hampered the development of new processes and products. To overcome this limitation, herein, we investigated the effects of tool radius, direction, and test speed on the formability to fracture of an AISI 430 stainless steel sheet under bending and stretching conditions. An equipment was used to perform the draw-bend fracture (DBF) test based on the bending under tension test. The DBF test efficiently reproduced the tensile, mixed, and shear fractures. Furthermore, we determined the fracture limit strain on the outer surface, thickness, and sidewall of the sample, as well as the coefficient of friction. The data showed that the radius to thickness ratio related to the process parameters had a direct impact on the experimental results. In addition, the results can be utilized for setting design guidelines and failure prevention.