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利用TEM和SEM观察了690合金管中TiN夹杂物的存在形式及其分布状态,通过高温高压电化学实验和应力腐蚀浸泡实验研究了690合金管在高温高压水溶液中的腐蚀和应力腐蚀行为.TiN是690合金管中一种主要的夹杂物,随机分布在奥氏体基体中.模拟压水堆核电站一回路水化学条件的高温高压电化学实验及能谱测试表明,点蚀优先发生在690合金管中含Ti夹杂物处.高温高压含Pb碱溶液中的应力腐蚀浸泡实验显示,690合金管表面的TiN和基体结合处的基体侧是优先发生腐蚀的位置,分布在晶界上的TiN和基体结合处发生腐蚀后容易导致局部应力集中,从而诱发沿晶应力腐蚀开裂.
The existence and distribution of TiN inclusions in 690 alloy tube were observed by TEM and SEM. The corrosion and stress corrosion of 690 alloy tube in high temperature and high pressure aqueous solution were studied by high temperature and high pressure electrochemical experiments and stress corrosion immersion experiments. TiN is a major inclusion in 690 alloy tube and is randomly distributed in the austenite matrix.HPV electrochemical experiments and energy spectrum tests on the water chemistry of the primary circuit of PWR nuclear power plant show that pitting corrosion takes place preferentially in 690 alloy tube containing Ti inclusions at high temperature and pressure of Pb-containing alkali solution stress corrosion immersion experiments show that 690 alloy tube surface of the substrate and the substrate side of the substrate is the preferred corrosion location, distributed in the grain boundary TiN and the substrate at the junction of the corrosion easily lead to local stress concentration, thereby inducing intergranular stress corrosion cracking.