Corrosion of titanium and titanium alloys

The use of titanium began in the 1950s, spurred on by the military aeronautics industry, then the civil aviation industry, due to its excellent mechanical strength to density ratio. But around a third of titanium metal production is used in the heat exchanger and chemical appliance industries. In this document, we present the different alloys used according to chemical environments; some alloys have been particularly developed for aggressive environments, and original solutions are currently being developed to offer more economical solutions. Type β alloys, which provide mechanical properties superior to those of unalloyed titanium, and α + β alloys are also presented, along with the influence of additive elements on corrosion resistance.

Behavior in gases, acids, chlorides and alkalis is described as a function of temperature and hydrogen potential (pH). The use of inhibitors is also discussed. The case of specific corrosion mechanisms, such as crevice corrosion and pitting, is illustrated. Limits to the use of titanium are also presented, mainly concerning fluorinated media.

Titanium's characteristics make it highly economical to use in the seawater sector, for exchangers in seaside nuclear power plants, seawater desalination plants being developed in the Persian Gulf countries, and more generally for on-board equipment on ships and off-shore platforms.

Titanium is also very popular for use in chemical process equipment in the form of plate or tube heat exchangers, as well as in clad-on-steel configurations: pulp bleaching, fertilizer manufacture, petrochemicals, organic acid production, mineral processing, waste treatment...

Furthermore, the consequences of air and water pollution mean that titanium will be an economical solution for guaranteeing the lifespan of plants.