材料期刊网

Corrosion fatigue damage and its electrochemical characteristics of high purity ferritic stainless steel (Fe-26Cr-1Mo) under symmetrical tension and compression strain control have been investigated in 1 M H2SO4 and 3.5 % NaCl solution by using three-electrode technique at imposed passive potential. The tests were carried out at the total strain amplitudes of 4 x 10(-3), 8 x 10(-3), 1.0 x 10(-2) and 1.2 x 10(-2). The effects of the strain amplitude on the electrochemical dissolution and plastic deformation on the surface were studied particularly. At low strain amplitude (DELTAepsilon(t) = 4 x 10(-3)), the passivity-maintaining current was small and stable because of the small slip activity. The maximum current at the tensile half cycle, l(t)p, was always bigger than l(c)p, or sometimes equal to l(c)p, the maximum current at the compressive half cycle in 3.5 % NaCl. At high strain amplitude (DELTAepsilon(t) = 1.2 x 10(-2)), the enhanced deformation on the surface induced the increasing dissolution. The increasing anodic current reflects the breakdown of the surface film, and only one current peak occurs within one cycle. At intermediate strain amplitude (DELTAepsilon(t) = 8 x 10(-3)), the current behaviour was very stable after cyclic hardening in 3.5 %, NaCl, but periodical jumpings of current during cycling were observed in the saturation region in 1 M H2SO4.