弯曲应力对经济型双相不锈钢LDX2101应力腐蚀影响的研究

Effect of Bending Stress on Stress Corrosion Property of 2101 Lean Duplex Stainless Steel

采用金相显微镜、电化学扫描极化曲线和电化学阻抗谱对承受不同变形程度的冷轧态LDX2101的显微组织、耐蚀性和腐蚀形貌进行了研究。结果表明:随着应力的增加降低了LDX2101表面钝化膜的稳定性,耐蚀性变差。应力作用使得LDX2101表面的腐蚀形貌发生了改变,呈现明显的选择性腐蚀。随着应力增加,腐蚀优先发生在α/γ相界和夹杂处,并逐渐向铁素体相扩散,腐蚀区域沿着应力方向逐渐被延长;由于拉应力的影响,处于表面或次表层的夹杂也参与了点蚀的形成,使得腐蚀向材料次表面或更深处的α相扩展。

The microstructure,corrosion resistance and corrosion morphology of the cold-rolled LDX2101 stainless steel with varying degrees of deformation were characterized by means of optical microscope, and potentiodynamic polarization, and electrochemical impedance spectroscopy. The result showed that： with the increase of stress, the stability of the passivation film on the steel surface was reduced, thus its corrosion resistance decreased obviously. The increasing of stress may also cause the change of corrosion morphology, and thus selective corrosion could clearly observed. As the increase of stress, the pitting preferentially occurred on α/γ phase boundary or inclusions, and then extended to ferrite phase, and thereby the corrosion morphology may elongate along the direction of tensile stress. Due to the action of tensile stress, inclusions located at the surface or subsurface are also involved in the formation of pitting corrosion, and therewith, the pitting corrosion extended to the α phase located at the substrate surface or even deeper.