Effects of hot rolling process on mechanical properties and corrosion resistance of Sn-containing ferritic stainless steel

Abstract

Cr-Ni resource-saving Sn-containing ferritic stainless steel (FSS) was taken as the research object. The microstructure evolution and properties change of the experimental steel under different hot rolling processes were explored by means of optical microscope(OM), electron backscattering diffraction(EBSD), X-ray diffraction(XRD), room temperature tensile test, electrochemical corrosion test, etc. The results show that when the finishing rolling temperature (FRT) is in the range of 940-730 ℃, properly reducing the FRT has a significant role in refining the grains of hot-rolled and annealed sheets and final cold-rolled and annealed sheets, as well as increasing the orientation density of recrystallization texture, and thus the yield strength, tensile strength and elongation are significantly increased. When the FRT is 800 ℃, the tensile strength is 509 MPa, the yield strength is 331 MPa, and the elongation reaches a maximum of 42%, and meanwhile, the maximum cupping value and plastic strain ratio are obtained, leading to the best mechanical properties. In addition, the pitting potential and self-corrosion potential are increased, while the corrosion current density and corrosion rate are decreased by properly reducing the FRT. When the FRT is 800 ℃, the pitting potential reaches the maximum, the corrosion current density reaches the minimum and corrosion rate reaches the lowest, thus the optimum corrosion resistance is obtained in the steel. The properties of Sn-containing FSS are significantly improved compared with SUS430 FSS by optimizing the hot rolling process.

Keywords

• ferritic stainless steel
• mechanical property
• corrosion resistance
• microstructure
• hot rolling