残余拉应力对304不锈钢电化学腐蚀行为的影响

摘要

The 304 stainless steel was processed into U-bend specimen and unloaded,and then the residual stresses at the tensile surface after unloaded were tested.The electrochemical corrosion behavior at the tensile surface of U-bend specimens with different curvature radii (i.e.different residual tensile stresses)in dilute sulphuric acid solution was also studied.The results show that the residual stresses at the tensile surface of U-bend specimen after unloaded were tensile stresses,and the residual stress increased with the decrease of the curvature radius.With the increase of the residual tensile stress,the initiating passivation current density and the passive current density of the specimen increased,while the repairing ability of the passive film weakened,resulting in the decrease of the pitting corrosion resistance.The dislocation density was a relatively high due to the relatively large residual tensile stress,resulting in a relatively large corrosion current.%将304不锈钢制成 U 型弯曲试样并卸载，对卸载后拉伸面的残余应力进行了测试，研究了不同曲率半径(即不同残余拉应力)弯曲试样拉伸面在稀硫酸溶液中的电化学腐蚀行为。结果表明：卸载后 U 型弯曲试样拉伸面的残余应力为拉应力，残余应力值随曲率半径的减小而增大；随着残余拉应力的增大，试样的致钝电流密度逐渐增大，维钝电流密度也随之增大，钝化膜的修复能力减弱，抗孔蚀能力变差；残余拉应力越大，位错密度越高，腐蚀电流也越大。