Microstructures and formability of type 304 stainless steel in deep drawing

On the structural inhomogeneity of austenitic stainless steels, investigations revealed that microstructures of deformation twins, shear band and martensites were generated during individual plastic deformation tests. They are of enough significant engineering importance in affecting the mechanical properties and the ductility and formability. The rapid rate of strain-induced martensitic transformation in type 304 stainless steel causes low ductility and leads readily to plastic instability. Martensitic transformation can be eliminated at an elevated temperature, but the ductility and the rate of strain hardening also decrease greatly. The formability of type 304 stainless steel sheet, especially from deep drawing, is poor in each case. However, those deformed structures may combine with each other, or generate microstructures of other types, when they deform in a complex temperature test. In the present work, the deformed microstructures of type 304 stainless steel in a complex deep-drawing test has been studied at the failure point by transmission electron microscopy. Various types of microstructures generated in this material to influence the formability will be described and explained.