Study On Correlation Between Microstructure And Corrosion Resistance Of TA2 Tianium Alloy

With the improvement of our country’s technology and economic level,higher corrosion resistance requirements have been put forward in many important fields for structural parts in service.As one of the commonly used materials for corrosion resistance,TA2 titanium alloy is used on a large scale in marine corrosion protection and other aspects,but the mechanism of microstructure on the corrosion resistance of TA2 titanium alloy is still unclear.In this thesis,the effect of microstructure on corrosion resistance and the corrosion mechanism after heat treatment and cold deformation is mainly investigated using TA2 titanium alloy as the research object.By changing the heat treatment holding temperature and holding time,investigating the relationship between heat treatment parameters and grain size,and determining the current density of specimens with different grain sizes,the grain size and the corrosion performance within the interval of 750℃～850℃and 0.5 h～8 h of heat treatment temperature and time were quantified,and the quantification equation is i_corr=7.02×10^-7-6.12×10^-8[1056001.32e^-10334/Tt^0.52]^-0.5,which can provide the production of TA2 titanium alloy.It can provide favourable data support for the production of TA2 titanium alloy.The relationship between different deformation variables and different deformation directions and corrosion performance was investigated using cold deformation compression experiments on isometric TA2 and slatted TA2 materials to investigate the corrosion mechanism of deformation on the corrosion resistance of TA2 titanium alloy by comparing the microstructure and corrosion performance of TA2 specimens with different deformation variables.After 10%,20%,30%and 40%deformation,the corrosion performance of isometric TA2 material increased and then decreased,and the best corrosion performance was found at 30%deformation with a self-corrosion current density of 4.112×10^-7A/cm².After unidirectional,bidirectional and three-way compression deformation,the corrosion performance of isometric TA2specimens increased and then decreased,and the best corrosion performance was found at bidirectional deformation with a self-corrosion current density of After 10%,20%,30%and 40%deformation,the corrosivity of TA2 material in slatted form first increased and then decreased,and the corrosivity was best at 20%deformation,with a self-corrosion current density of 3.924×10^-7A/cm²,and after unidirectional,bidirectional and three-way compression deformation,the corrosivity of isometric TA2 specimens first increased and then decreased,with a self-corrosion current density of 3.924×10^-7A/cm².The corrosion performance of TA2 specimens was first improved and then reduced,with the best corrosion performance at two-way deformation and a self-corrosion current density of 2.668×10^-7A/cm².Both heat-treated and cold-deformed TA2 specimens produced a dense oxide film on the surface after corrosion,with Ti O₂as the main component.Compared to the original TA2 specimen,the deformed 30%specimen showed an increase of4.02 at.%at 0 nm and a decrease of 2.21 at.%,1.80 at.%and 4.10 at.%at 5 nm,10nm and 15 nm,respectively.The passivation film of the deformed titanium alloy is denser and thinner,with better protection and better corrosion resistance.The dislocation density increases as the deformation increases,resulting in a rapid nucleation of the passivation film.However,too high a density of dislocations and an increase in residual stress can reduce the corrosion resistance of titanium alloys due to excessive defects.The results of this thesis obtain a quantitative relationship between heat treatment parameters and the corrosion resistance of industrial TA2 titanium alloy on the one hand,and also refine the mechanism of the effect of microstructure on the corrosion performance of TA2.The results of this thesis are of great significance for the optimisation of the corrosion resistance of industrial TA2 titanium alloy and provide strong support for the development and application of industrial TA2 titanium alloy.