Causes of Cracks in Galvanized Steel Fence Posts

Bad Steel

• Numerous methods of creating galvanized steel exist. Because of this, the quality of galvanized steel varies greatly. Hot-dip galvanization, for instance, entails dipping a piece of steel in molten zinc, so that the outer layer of steel melts and forms an alloy coating with the zinc. Some manufacturers eschew this method due to its high cost and complicated production, preferring instead to simply adhere a layer of zinc on top of steel. Galvanized steel with a thin or weak layer of zinc may crack easily. Poorly adhered or misshaped zinc also cracks and breaks more easily than hot-dip galvanized steel coatings.

Welding Problems

• The welding process can cause problems with galvanized steel, including cracking. Welding together two metals of different thicknesses can increase the hardness of these metals. For instance, welding very strong galvanized steel fence posts to less strong galvanized steel or other metals can increase the hardness of the strongest metal. Strong galvanized steel becomes brittle as its hardness increases. If the hardness goes beyond a certain point – above a tensile strength of 160,000 pounds per square inch – galvanized steel becomes brittle and can crack. This problem only occurs at or around welded areas.

Manufacturing Issues

• Engineer and author Richard M. Beldyk argues against traditional methods of blame for cracks in galvanized steel, such as bad steel. Beldyk argues that galvanized steel commonly cracks during the manufacturing process, but the outer layer of zinc obscures these problems. For instance, zinc or steel may crack during hot-dip galvanization, but as zinc hardens after the melting process, it can expand to cover – but not fill – these cracks. Over time, these cracks become larger, making it seem as though the material only recently cracked. Beldyk recommends always using a trained visual inspector before installing any galvanized steel, including fence posts.

More Information

• Various other causes of cracked galvanized steel may occur. For instance, galvanized steel deteriorates more quickly in coastal areas than in areas far from the ocean. Galvanized steel also deteriorates quickly when driven into the ground – if your fence is not rooted in concrete but driven directly into soil, this may cause cracks and other problems. When it comes to determining the exact cause of your cracks, bring in a third-party inspector or other steel expert. Avoid contacting your fence company, which may fudge the truth. An expert can repair cracks for you, though with poorly manufactured steel, this may not prove cost-effective.