Agozal DoubleDip®, twice-galvanized steel coil from ThyssenKrupp Steel, has been approved as a material for highway crash barriers. After five years of long-term trials by the German Federal Highway Research Institute (Bundesanstalt für Straßenwesen, BASt) and further investigations by the Federal Institute for Materials Research and Testing (Bundesanstalt für Materialforschung und –prüfung, BAM), it is now official: Crash barrier beams made of Agozal DoubleDip® fit the purpose just as well as batch-galvanized barriers. What the two federal authorities did not test but is easily demonstrable is that crash barriers made of Agozal DoubleDip® are more cost-effective than batch-galvanized barriers.
To date, crash barrier manufacturers have worked with hot-rolled steel strip, which they profile before dipping each finished part into a zinc bath. For a long time, this batch galvanizing was regarded as the best possible solution in terms of long-term corrosion protection for steel crash barriers. Now in Agozal DoubleDip® a material has been approved for this application which offers at least the same degree of corrosion resistance – straight from the factory. The steel strip needs only to be profiled before it is ready for use as a crash barrier beam. All the logistics involved in batch galvanizing, and the associated costs, are eliminated. The material is also suitable for motorcycle underrun protection beams.
Agozal DoubleDip® is produced at the Neuwied plant of ThyssenKrupp Steel AG. There, Germany’s biggest steelmaker operates a unique hot dip galvanizing line in which steel can be passed optionally through one or two zinc baths. If it goes through two, the result is Agozal DoubleDip®. The first coat consists of pure zinc, the second a mixture of 95 percent zinc and five percent aluminum. The continuous coating process produces a coating which is extremely adherent, allowing the steel strip to be formed without difficulty. The process also uses less zinc, which keeps costs down. By way of comparison: The uniformly 42 micrometers thick zinc coating on the material now approved for crash barriers offers the same corrosion protection as the zinc coating applied by batch galvanizing, which varies on average between 70 and 110 micrometers in thickness.