Pitting initiation and growth model of Ti6321 welded joint in seawater environment
In view of the pitting risk that titanium alloy welded joints may face in long-term service in seawater,the pitting initiation and growth behavior of Ti6321 welded joint in seawater environment were investigated by electrochemical testing,bending loading and immersion test of prefabricated pitting specimens,combined with statistical analysis methods such as cumulative probability and distribution function.A kinetic model of pitting growth was established by using extreme statistical method.A kinetic model of pitting growth was establised by using extreme statistical method.The results show that the initiation time includes the time when the driving potential of pitting initiation reaches the threshold potential and the induction time of the generation of metastable pitting and its transition to steady pitting.Based on the experimental and theoretical calculation results of pitting initiation time,it is conservatively estimated that under free corrosion conditions in stagnant seawater,it is diffucult for Ti6321 welded joints to spontaneously produce steady-state pitting corrosion.The maximum pitting depth of Ti6321 welded joint in seawater under 90%Re bending loading conforms to the Gumbel distribution.This study provides a prediction method based on electrochemical and statistical analysis for the quantitative evaluation for pitting initiation and growth of titanium alloy in seawater environment.
NETL
NSTL
万方数据
