Galvanized fasteners, such as nails and bolts are ideal when strength, corrosion resistance and economy are all concerns. However their thin coatings of Zinc can become damaged and allow the steel below to begin corroding.
Galvanized fasteners with a broken coating may begin to corrode and stain the surface with a rust colored streak.
The galvanized bolts in the picture to the right were used to attach an outboard motor mounting bracket to a wooden boat. Over time, the motor's vibrations wore through the galvanized coating and allowed the steel below to corrode. Both ends of the bolts appeared to be in a good condition; however, removal showed they were ready to break. In this application, high strength stainless steel would have been the best choice.
Galvanized deck screws are popular for use in outdoor environments.
However, if the surface of the galvanized coating is broken during installation rust will form and discolor the screw's head.
Galvanized coatings are ideal when price is a concern. In marine applications and severe environment other materials such as stainless steel or silicone bronze might be a better choice.