Resistance to Forms of Corrosive Attack

Titanium and its alloys typically exhibit an excellent resistance to corrosion. Titanium is generally resistant to oxidation, galvanic corrosion, SCC, corrosion fatigue, and erosion corrosion. A few of the forms of corrosion and their correlation to titanium are briefly discussed in the following sections.

Stress Corrosion Cracking

Titanium is susceptible to SCC in the presence of hot-salts or gaseous chloride ions and residual stresses. Severe SCC usually only occurs in the presence of hydrobromic acid or red fuming nitric acid at elevated temperatures; otherwise SCC is not much of a threat to titanium, which is also generally resistant to SCC in seawater, fresh waters and body fluids. Titanium has exhibited susceptibility to SCC in liquid and gaseous oxygen at cryogenic temperatures.

Pitting

The occurrence of pitting on titanium is rare, although it can result from iron adsorbed on the surface of titanium. Titanium resists pitting better than stainless steels and copper-nickels.

Other Forms

Titanium is susceptible to crevice corrosion, to liquid metal embrittlement in the presence of Cd and Ag, and is also susceptible to embrittlement as a result of the dissolution of hydrogen, oxygen, and nitrogen. Furthermore, titanium and its alloys have a high susceptibility to fretting at interfaces with titanium or other metals, which can significantly reduce its fatigue life. Titanium does, however, have a strong resistance to erosion corrosion and impingement attack, as well as a good resistance to corrosion fatigue.