Weathering steel is progressively corroding, sometimes at an increasing rate if moisture is prevalent. Thus, there is a loss of steel mass and the fatigue strength is lessened. This means that a design using weathering steel may require thicker sections in order to account for the loss of cross-section. • Hot-dip galvanized (HDG) steel protects the substrate steel and there is no loss of steel mass.Weathering steel exposed to constant wetting will corrode the same as unprotected carbon steel. Weathering steel needs to have a 50-50 wet/dry cycle in order to form the stable patina of tightly-bound corrosion products.