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从环境角度研究了敏化1Cr18Ni9Ti不锈钢在高温水中的腐蚀行为.研究指出,在一定浓度Cl~-和(或)O_2存在情况下,在酸性和中性高温高压水中都会出现应力腐蚀破裂.断口电子金相表明,在氯离子为主的环境中,破裂系晶间型;在氧为主的环境中,破裂系以解理为主的混合型.给出了1Cr18Ni9Ti在高温水中腐蚀的表观和真实动力学曲线,表明腐蚀包含溶解和湿氧化两部分,而以湿氧化为主.借Mossbauer内转换电子谱研究了氧化膜结构与腐蚀的关系,指出在一般腐蚀条件下,膜的主要组分为Fe_3O_4,而在应力腐蚀条件下,膜的主要组分为Fe_2O_3,并且系Fe_2O_3和Fe_3O_4多层重叠结构.当水中添加了一定量的硼,在氧化膜中会局部出现FeBO_3相,既不会引起也不会抑制应力腐蚀.硼的这种“惰性”作用和膜结构中Fe_3O_4相的非化学计量比,膜具有阴离子选择性有关.根据腐蚀电化学,认为应力腐蚀系发生在钝化/过钝化区域,增高Cl~-或O_2含量,从不同角度都会使合金的电位接近过钝化区.Cl~-的作用在于改变阳极极化曲线,O_2的作用在于改变阴极极化曲线.在含Cl~-水中,晶界TiC的迅速溶解是应力腐蚀的主要原因,而在含氧水中,晶粒Fe-Cr-Ni中Cr的选择性溶解是应力腐蚀的主要原因.在分析应力腐蚀的特征后,指出应力既是某些严重腐蚀点形成原因之一,而且应力可能产生的活性途径也将适应、加速并指引某一严重腐蚀点金属原子作有规则的溶解.据此初步提出1Cr18Ni9Ti不锈钢在高温高压水中应力腐蚀破裂的过程.
The corrosion behavior of sensitized 1Cr18Ni9Ti stainless steel in high temperature water was studied from the environmental point of view.The results show that stress corrosion cracking occurs in acidic and neutral high temperature and high pressure water under the presence of Cl ~ - and / or O 2. Metallographic evidence shows that in the chloride-dominated environment, the rupture system is intergranular and in the oxygen-dominated environment, the rupture system is dominated by cleavage.The apparent corrosion of 1Cr18Ni9Ti in high temperature water The real kinetic curve shows that the corrosion consists of dissolved and wet oxidation and the wet oxidation is dominant.The relationship between the oxide film structure and corrosion is studied by Mossbauer internal conversion electron spectroscopy.The results show that under the general corrosion conditions, Is Fe 3 O 4, while under the stress corrosion condition, the main component of the film is Fe 2 O 3, and is a multi-layer structure of Fe 2 O 3 and Fe 3 O 4 .When a certain amount of boron is added to the water, the FeBO 3 phase appears locally in the oxide film, Caused by nor will it inhibit stress corrosion.Because this “inert” effect of boron is related to the non-stoichiometric ratio of the Fe_3O_4 phase in the film structure and the anion selectivity of the membrane.According to the corrosion electrochemistry, stress corrosion is believed to occur at Passivation / over passivation region, increase Cl ~ - or O_2 content, from different angles will make the alloy near the over-passivation potential.Cl ~ - role is to change the anodic polarization curve, O_2 role is to change the cathode polarization The rapid dissolution of TiC at the grain boundary is the main cause of stress corrosion in Cl ~ - water, whereas the selective dissolution of Cr in grain Fe-Cr-Ni is the main cause of stress corrosion in oxygenated water.In the analysis Stress corrosion characteristics, pointed out that stress is not only one of the reasons for the formation of some serious points of corrosion, and stress may be generated by the active pathway will also adapt to speed up and guide a serious corrosion point of the metal atoms for the rule of dissolution. 1Cr18Ni9Ti stainless steel in high temperature and pressure water stress corrosion cracking process.