Study of the stampability of AISI 441 steel under different initial conditions

Abstract

The deep drawing process in metallic materials has several limitations, such as a stamped depth, the occurrence of wrinkles, the fracture of the sheet before total deformation and the generations of solids with variations in wall thickness. Considering these variables, this work studies the formability of AISI 441 stainless steel under different initial conditions, namely, as-received and rolled to investigate the effect of these variables on the formability of this ferritic stainless steel. The mechanical characterization of AISI 441 steel involved tensile, shearing and Vickers microhardness tests followed by cold stamping, using a deep stamping die. The structural investigation was accomplished by optical microscopy and electron backscatter diffraction techniques. The mechanical behaviour after the stamping process was analyzed by shearing tests on the bottom and wall of the cup and correlated to the deformation limit of the material, and the respective texture characteristics. The shearing test results indicated the effect of the initial condition on the mechanical behaviour after the stamping of AISI 441 steel, which exhibited hardening of the wall and softening at the bottom of the cups. Change in misorientation grain and strengthening of γ-fiber texture component for the rolled condition of AISI 441 steel.