几种超级不锈钢在模拟烟气脱硫环境中的点蚀行为

目前,针对904L,254s Mo和2507等几种主要备选超级不锈钢在烟气脱硫环境中的耐点蚀性能缺乏系统研究。在温度分别为20、40、70℃的死亡绿液溶液中,利用循环伏安曲线和扫描电镜(SEM)法,对316不锈钢和超级不锈钢904L、254s Mo及2507的极化行为和点蚀形貌进行了研究。结果表明:在该环境中,升高温度可降低4种不锈钢表面钝化膜稳定性并提高其点蚀敏感性;在不同温度环境下,316不锈钢均有严重的点蚀现象发生,而254s Mo和2507不锈钢表面均无明显点蚀迹象;在20℃时,904L不锈钢表面无明显点蚀迹象,40℃时,其表面出现典型的点蚀形貌,但点蚀坑尺寸较小,在70℃的高温下,其点蚀坑尺寸明显增大,点蚀损伤严重;254s Mo和2507均适合作烟气脱硫设备材料,而316、904L在该环境中需谨慎使用。

Pitting Behaviors of Several Super Stainless Steels in Simulated Flue Gas Desulfurization Environment

In this work,the cyclic polarization behavior and surface morphology of pitting on 316,904L,254sMo and 2507 stainless steels had been investigated in death green solution at different temperatures (20,40,70 ℃) by electrochemical cyclic polarization test and SEM,respectively.Results showed that the increase of temperature could reduce the stability of passivation films of 316,904L,254sMo and 2507 stainless steel and increase the pitting sensitivity.At different temperature environment,serious pitting corrosion occurred on the surface of 316 stainless steel,while no obvious pitting corrosion morphology was found on those of 254sMo and 2507 stainless steel.At 20 ℃,there was no obvious pitting corrosion on the surface of 904L stainless steel.At 40 ℃,the typical pitting corrosion morphology appeared on the surface,while the pitting size was smaller.At 70 ℃,the size of pitting pit increased obviously,and pitting corrosion was serious.Furthermore,both 254sMo and 2507 were suitable to be used as flue gas desulfurization materials,while 316 and 904L should be used with extreme caution under this environment.