材料期刊网

用慢应变速率方法(SSRT)评价了合金元素氮对00Cr18Ni5Mo3Si2(18-5Mo)钢SCC 性能的影响.发现适宜的含氮量为0.11%,此含氮量的钢最耐30%MgCl_2(沸)溶夜中的应力腐蚀破裂(SCC)。由恒电位 SSRT 实验,得出三种不同含氮量的钢的 SCC电位范围和临界破裂电位。结果表明,氮提高了应力腐蚀临界破裂电位,阳极极化降低了氮的作用,当阳极极化至-350mV(SCE)以上时,氮几乎不起作用。氮改变了相比例,从而影响双相钢性能。扫描电镜(SEM)、能谱仪(EDAX)配合金相分析发现:阳极极化削弱了氮通过两相比例对双相钢 SCC 性能的影响。在开路电位下,α、γ相均对裂纹的发展起阻止作用;在较低的阳极极化电位下.α、γ相均对裂纹起一定阻止作用,在较高阳极极化电位下,它们对裂纹的阻止作用消失。由此认为较高的阳极极化电位使α相γ相的电化学保护作用消失。

The slow strain rate technique(SSRT)was used to evaluate the influence of nitrogen on SCC behavior of 00Cr18Ni5Mo3Si2 duplex stainless steel in 30%MgCl_2(boiling)solu- tion.It was found that the 00CrMo3SiCl_2 steel containing 0.11% nitrogen showed the best resistance to SCC.The critical cracking potentials of three steels with different content of nirogen were measured.The results showed that nitrogen increased the SCC critical po- tential,but the effect of nitrogen was weakened by anodic polarization.When the external polarization potential was more than-350mV(SCE),the effect of nitrogen was not obvi- ous.Nitrogen influenced the SCC behavior of the duplex steel by varying the proportion of two phases in the steel.By using SEM,EDAX and metallographic techniques,it was found that the anodic polarization weakened the effect of nitrogen on SCC behavior of the du- plex stainless steel.Under the condition of natural corrosion,γ phase retarded propagation of cracks:under lower anodic potentials both α and γ phases have a certain retardant ef- fect on the propagation of cracks:under higher anodic potentials the retardant effect of phases disappeared.It was mought that the anodic polarization potentials made the electro- chemical protection effect of α phase to γ phase disappear.