工业纯钛TA2在含硫化物深海水环境中的应力腐蚀行为

Stress Corrosion Cracking Behavior of Industrial Pure Titanium TA2 in Sulfide Containing Deep Seawater Environment

深海水环境具有静水压力大、溶氧量低、侵蚀性离子复杂等特点,使得深海水环境具有较强的腐蚀性。目前,钛及钛合金在深海环境下的腐蚀及应力腐蚀行为机理尚不清楚,这对钛合金在深海环境中的应用造成较大的威胁。文中采用电化学方法及U型弯试验研究了工业纯钛TA2在模拟深海环境下的电化学行为及应力腐蚀行为。结果表明,静水压力对TA2均匀腐蚀及阴极析氢反应均有所促进,随着静水压力增大,TA2腐蚀电流密度及析氢电流密度均增加。硫化物的加入一定程度上降低了TA2钝化膜稳定性,并对阴极析氢反应有较为明显的促进。应力腐蚀试验表明深海硫化物作用下TA2具有一定的应力腐蚀敏感性。TA2在深海条件下,虽然SCC以氢致开裂为主,但是由于氧含量与浅海等环境的不同,阳极溶解机制也是TA2在深海条件下SCC开裂的原因。

The deep seawater environments is highly corrosive due to the characteristics of large hydrostatic pressure,low dissolved oxygen and complex aggressive ions.The corrosion and stress corrosion mechanisms of titanium and titanium alloys in deep sea environment are still unclear,which poses a great threat to the application of titanium alloys in deep sea environments.The electrochemical behavior and stress corrosion behavior of industrial pure titanium TA2 in simulated deep sea environment were studied by electrochemical method and U-bend test.Results show that the hydrostatic pressure promotes the uniform corrosion of TA2 and the cathode hydrogen evolution reaction(HER).With the increase of hydrostatic pressure,the corrosion current density and cathode HER current density of TA2 increase.The addition of sulfides reduces the stability of the TA2 passive film to a certain degree,and promotes the cathode HER.The stress corrosion test shows that TA2 has stress corrosion sensitivity under the effect of sulfide ions in deep sea water.The SCC mechanism is mainly hydrogen-induced cracking for TA2 in deep seawater environment.However,due to the difference in oxygen content between deep sea and shallow sea,anodic dissolution mechanism is also one of the reasons for SCC.