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Corrosion resistance of titanium alloy in marine environment

Titanium alloy exhibits excellent corrosion resistance in marine environment, which makes it widely used in marine engineering. The corrosion resistance of titanium alloy is even better than that of aluminum alloy, stainless steel and nickel-based alloy, so it is known as "marine metal".

Reasons for corrosion resistance of titanium alloy:
• Passivation film Titanium alloy can form a stable oxide film in seawater, which effectively prevents corrosion. Even in the presence of chloride ions, the oxide film on the surface of titanium can still effectively prevent corrosion.

• General corrosion resistance Titanium can resist seawater corrosion, even at temperatures as high as 260°C. Titanium pipes exposed to polluted seawater for 16 years only slightly discolored and showed no signs of corrosion. Even at a depth of one mile below the sea surface, titanium did not produce any measurable corrosion.

• Erosion resistance Titanium can resist the erosion of high-speed seawater, and even at speeds as high as 120 feet per second, the corrosion rate only increases minimally.

• Anti-microbial corrosion Titanium is immune to corrosion caused by microorganisms, and there are no cases of microbial corrosion of titanium reported.

• Electrochemical stability Titanium alloys have high electrochemical stability and self-passivation ability, which makes them exhibit good corrosion resistance in marine environments.

Factors to note:
• Deep-sea environment As the service depth increases, the low temperature, low oxygen and high pressure environment of the deep sea will reduce the passivation performance of titanium alloys and increase the risk of local corrosion and stress corrosion cracking.

• Wear corrosion Titanium alloys have poor wear resistance, and friction and wear can easily lead to the removal of the passivation film and accelerate corrosion.

• Stress corrosion cracking Under conditions of high stress and pre-existing cracks, some titanium alloys may be sensitive to stress corrosion cracking in seawater.

Despite the above problems, titanium alloys are still an important marine material, and their excellent comprehensive properties have led to their increasing application in deep-sea equipment.