深海环境对激光选区熔融Ti6Al4V应力腐蚀断裂行为的影响

Effect of Deep Sea Environment on the Stress Corrosion Cracking Behavior of Laser-selected Fused Ti6Al4V

目的比较增材制造技术制备的Ti6Al4V相比于传统锻造材料在深海环境下耐应力腐蚀性能的差异。方法利用慢应变速率拉伸、扫描电镜观察、XPS分析,对比了锻造的Ti6Al4V合金(WT-Ti6Al4V)和激光选区熔融技术制备的Ti6Al4V合金(SLM-Ti6Al4V)在海洋环境中不同静水压力(0、4、8 MPa)、温度(5、15、25℃)、溶解氧浓度(0.36、2、6 mg/L)下的应力腐蚀开裂行为以及深海环境下的钝化膜成膜行为。结果随着溶解氧浓度和温度的降低,静水压力的增大,两种材料的应力腐蚀敏感性均明显增加,钝化膜中TiO_(2)相对含量降低。横向比较表明,SLM-Ti6Al4V应力腐蚀敏感性系数较低,比WT-Ti6Al4V拥有更优良的耐应力腐蚀性能。结论不同环境参数会影响材料表面钝化膜中TiO2相对含量的变化,从而影响钝化膜对金属材料基体的防护作用。

This paper compares the stress corrosion resistance of Ti6Al4V prepared by additive manufacturing technology with that of traditional wrought materials in deep sea environment.The stress corrosion cracking behavior of wrought Ti6Al4V alloy(WT-Ti6Al4V)and SLM-produced Ti6Al4V alloy(SLM-Ti6Al4V)under different hydrostatic pressure(0,4,8 MPa),temperature(5,15,25℃)and dissolved oxygen concentration(0.36,2,6 mg/L)in the marine environment and the film formation behavior of passive film in deep sea environment was analyzed and compared by slow strain rate tensile,scanning electron microscopy and XPS.The experimental results show that with the decrease of dissolved oxygen concentration and temperature and the increase of hydrostatic pressure,the stress corrosion sensitivity of the two materials is significantly increased,and the relative content of TiO_(2) in the passive film decreases,the horizontal comparison shows that SLM-Ti6Al4V has better corrosion resistance.Different environmental parameters will affect the relative content of TiO_(2) in the passivation film on the material surface,thereby affecting the protective effect of the passivation film on the metal substrate.