A: That would depend on the application. Titanium bolts are ideal for high strength applications – especially when lightweight fasteners are needed. Titanium screws are also excellent in saltwater and chloride conditions – among the best materials for these corrosion issues. Titanium screws are also bio compatible so they are often used in the medical field.
Titanium is not good in acids like sulfuric or hydrochloric because they require oxygen (even in water) to regenerate their passive/protective layer. Acids rapidly destroy this layer and hence corrode titanium. Titanium also isn’t ideal for high temperature conditions with a maximum usable temperature of about 500F.