Corrosion Risk of Using Stainless Steel Bolts for A1010 Steel Bridge Girders

摘要

This experimental study evaluates the galvanic corrosion risk between stainless steel bolts and ASTM A1010 steel bridge girders. Two stainless steel structural bolts, ASTM A320 B8 Class 2 and A193 B6 stainless steel bolts, are studied, because they are currently deemed to be compatible with, and recommended for use in new A1010 steel bridge girders. In the electrochemical experiments, the galvanic coupling current and potential are obtained in aerated salt solutions that simulate chloride-laden environments for A1010 steel bridges. The results show that B6 stainless steel might not be adequate in corrosive environments, because it was found to suffer severe pitting corrosion, and the galvanic corrosion risk of using B8 bolts with A1010 steel was found to be negligible. This finding will be further validated by the visual examinations of bolted A1010 steel plates in salt spray testing and confirmed by the pitting corrosion of B6 washers used in an A1010 bridge after 1 year of service. This study demonstrates that the galvanic corrosion risk has to be studied through properly designed corrosion experiments, and deductions from conventional knowledge of the composition of materials and their corrosion resistance is not sufficient to understand the actual galvanic corrosion risk of dissimilar metals in bridge applications.