Titanium alloy has a low density, high strength, corrosion resistance, good process performance, etc., it is ideal aerospace engineering (34.27, 0.85, 2.54%) structural materials. In the actual production environment, different types of corrosion will occur, Detect-Metals will introduce the common corrosion forms of titanium alloy, mainly the following categories:
1, crevice corrosion
Gaps in metal structures or defects, due to the stagnation of the electrolyte constitute an electrochemical cell and cause localized corrosion in neutral and acidic solution, contact corrosion occurs at the gap is much greater than the probability of titanium alloy alkaline solution, contact corrosion does not occur Throughout the slit surface, but eventually lead to local perforation damage.
In most titanium salt solution without pitting, which occurred in a non-aqueous solution and high boiling concentrated chloride solution, the solution of halide ions on the surface of the passivation film is etched titanium, titanium internal diffusion to occur pitting , pitting diameter less than its depth. Some organic medium and titanium alloy pitting phenomenon will occur in the halogen solution, titanium alloy pitting halogen solution generally occurs at high concentrations high temperature environment, in addition, sulfide and chloride pitting require specific conditions and limited.
3, hydrogen embrittlement
Hydrogen embrittlement (HE), also known as hydrogen induced cracking or hydrogen damage, is one of the early damage Failure titanium alloy, titanium and titanium alloy surface passivation film has a high intensity, sensitive to hydrogen embrittlement increases with the intensity increases, the passivation film is sensitive to hydrogen embrittlement.
4, contact corrosion
Titanium oxide surface passivation film of titanium alloy potential toward a positive potential to promote and improve the corrosion resistance of titanium acid and aqueous medium. Due to the high potential of the titanium surface, it will inevitably result in the formation of other metals in contact with an electrochemical circuit caused by contact corrosion. Titanium alloy prone to contact corrosion in the following types of media: the first is water, saline solution, water, air, HNO3, acetic acid, etc., stable electrode potential of the solution Cd, Zn, Al is more negative than Ti, anode corrosion 6 to 60 times the rate of proliferation of said second type is H2SO4, HCl, etc., Ti in these solutions may be in the passive state, it may be in the activation state, the actual contact corrosion is common during the first class solution corrosion. Usually anodized layer on the substrate surface modified form, hindering contact corrosion.