表面粗糙度对316L不锈钢亚稳态孔蚀行为的影响

用恒电位和动电位下的电流-时间记录法研究了表面粗糙度 对316不锈钢亚稳态孔蚀行为的影响.结果表明，表面粗糙度增大使亚稳孔的形核数明显增 加，亚稳孔电流峰值也有所增大，亚稳孔生长速度则略有下降.提出了一个表征表面沟槽“ 开放度”的参量w/d，w/d值越大则表面越平坦，亚稳态小孔越难于形核.一定的电位和溶 液条件下存在一个临界w/d值，只有w/d值低于此临界值的表面才能形成亚稳态小孔.随w/d 值增大，亚稳态孔蚀电位Em和稳定孔蚀电位Ep都逐渐正移.用w/d值定性解 释了表面粗糙度与亚稳态小孔形核速率、峰值电流和生长速度之间的关系.

EFFECT OF SURFACE ROUGHNESS ON METASTABLE PITTING BEHAVIOR OF STAINLESS STEEL

The metastable pitting behavior of 316L stainless s teel with different surface roughness in 0.01 mol/L NaCl solution was studie d us ing potentiostatic and potentiodynamic polarization methods and statistical trea tments.As surface roughness decreased,the nucleation rate of metastable pits dec reased.The peak current of metastable pits also decreased,but the average growth rate of metastable pits showed a slight increase.An openness parameter,w/d, was suggested to characterize the openness of surface grooves,in which w is the width of the groove at the opening and d the depth of the groove.Bigger w/d value means more smooth surface,and it is more difficult for micro-pit t o nucleate.Under certain condition of solution and potential,there is a critical w/d value.Metastable pits may nucleate only on those surfaces whose w/d values are lower than the critical value.As the openness parameter w/d incr eases,the nucleation rate of metastable pits decreases linearly,and both metasta ble pitting potential Em and pitting potential Ep move in the positi ve direction.