Titanium is a low-density element (approximately 60% of the density of iron) that can be highly strengthened by alloying and deformation processing. Titanium is nonmagnetic and has good heat-transfer properties. Its coefficient of thermal expansion is somewhat lower than that of steels and less than half that of aluminum. Titanium and its alloys have melting points higher than those of steels. Titanium has the ability to passivate and thereby exhibit a high degree of immunity to attack by most mineral acids and chlorides. Titanium is  nontoxic and generally biologically compatible with human tissues and  bones. The combination of high strength, stiffness, good toughness, low density, and good corrosion resistance provided by various titanium alloys at very low to elevated temperatures allows weight savings in aerospace structures and other high-performance applications. The excellent corrosion resistance and biocompatibility coupled with good strength make titanium and its alloys useful in chemical and petrochemical applications, marine environments, and biomaterial applications.

Because of its particular importance to manufacturers of heat exchangers, titanium is often compared to zirconium because of their common properties. Both, for example, are used in salty environments because they form stable corrosion resistant oxide films on their surfaces. Zirconium has more resistance to reducing acids and can withstand sulfuric acid concentrations up to 70% at lower temperatures, but titanium is often more practical for hot dilute acidic chloride solutions with oxidizers. Zirconium is preferred for processing many organic compounds like citric or acetic acids. See also http://www.evanstechnology.com/zirconium.html.