The density of titanium bolt is 4.51g/cm3, which is 57% of steel; Titanium bolt weighs less than twice as much as aluminum but three times stronger than aluminum. Specific strength is the ratio of strength to density. Compared to different materials, the specific strength of titanium alloy is almost the largest in common industrial alloys. The specific strength of titanium alloy bolt is 3.5 times that of stainless steel, 1.3 times that of aluminum alloy and 1.7 times that of magnesium alloy, so it is an essential structural material for the aerospace industry. The comparison of density and specific strength between titanium and other metals is shown in below table.