The following demonstrates the feasibility of using hot-dip galvanizing to produce corrosion protection for ASTM A490 bolts without making them susceptible to hydrogen embrittlement. Currently, it is prohibited in North America to use most zinc corrosion protection systems including hot-dip galvanizing on high-strength bolts, namely ASTMA490 (Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength) bolts, which have tensile strengths greater than 150 ksi and up to 173 ksi. The purpose of the study described in this article is to demonstrate that ASTMA490 bolts can be galvanized using special bolt cleaning procedures without inducing hydrogen embrittlement into the bolts. The test procedure being followed for this study was produced by the Industrial Fasteners Institute (IFI) (IFI 144, Test Evaluation Procedures for Coating Qualification Intended for use on High-Strength Structural Bolts). All tests required in the IFI 144 standard were conducted on ASTM A490 bolts that have been mechanically cleaned to remove organic materials and iron oxide from the surface of the bolt before being hot-dip galvanized. Although high-strength bolts are regularly galvanized in Europe, the current ASTM A490 specification in North America will not allow high-strength bolts to be zinc coated. This study demonstrates the feasibility of using hot-dip galvanizing to produce corrosion protection for ASTM A490 bolts without making them susceptible to hydrogen embrittlement.
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