Microstructure evolution and corrosion behavior of 316L stainless steel subjected to torsion

The microstructure evolution of 316L stainless steels subjected to torsion deformation and its corrosion resistance in 1 M H2SO4 solutions were studied. Microstructure evolution of the annealed and torsion-processed samples was characterized by x-ray diffraction and electron backscatter diffraction techniques. The results showed that no martensitic transformation occurred during torsion deformation, while dynamic recrystallization occurred within the samples slowing down the tendency of increasing dislocation density and storage energy. Electrochemical tests including potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) were used in the 1 M H2SO4 solution to evaluate the corrosion resistance of the annealed and torsion-processed samples. The results illustrated that small deformation (torsion for 1 turn) could enhance the corrosion resistance of the 316L stainless steels by increasing the stability of the passive film, the medium deformation (torsion for 3 turns) will deteriorate the corrosion resistance due to high-density dislocations formed during torsion deformation, while large deformation (torsion for 5 turns) could improve the corrosion resistance compared with the medium deformation due to the occurrence of dynamic recrystallization and the high-density deformation twins formed.