Mechanical Properties of Hot-Dip Galvanized Steel

Abstract

The hot-dip galvanizing process takes place in a molten bath of zinc metal at a temperature of 840 ± 20°F. The coating process takes only a short time at this temperature, usually less than 5 minutes, so this limits the potential changes to the mechanical properties of the steel that is being galvanized. This study examined steels that are commonly used for structural assemblies, A 36 and A 572 grades 50 and 65. Cold work processes and welding procedures were performed on these steels before the hot-dip galvanizing process to verify that the immersion in the liquid zinc bath would not affect the mechanical properties of the structural steels. This study follows the procedures and testing protocol established in a previous test of the hot-dip galvanizing process. The book was the culmination of four years of intensive research conducted at the BNF Metals Technology Centre in England under the sponsorship of the International Lead/Zinc Research Organization (ILZRO). The researchers examined 19 different steels from all over the world that were readily available in the 1970's. Many of the common fabrication practices were used on these steel samples and the mechanical properties of the steel were examined after hot-dip galvanizing. The general conclusion form this report is that the hot-dip galvanizing process had no major affect on the mechanical properties of the structural steel. The present work was to test the response of three grades of structural steel that is commonly used for structural assemblies in North America to cold work, bending and welding operations typically used in fabricating assemblies with these steels. Tensile properties were determined on the as-received steel, 10% cold rolled, 40% cold rolled, welded, hole punched and bent samples. All steel grades were tested in the uncoated and the fully galvanized states. Tensile test, Charpy impact tests and hardness testing were all performed on the steel samples.