Abstract
Weathering steel were steel with high atmospheric corrosion resistance by alloying Cu, Ni, etc. Use of weathering steels was limited by environmental conditions especially for airborne salts. Thus, new weathering steels with higher corrosion resistance in more salty condition were developed by adjusting composed elements. However, increasing alloying element will increase its cost. Thus, selecting weathering steels fit for construction sites is important. This study is aiming to understanding relationships among corrosive resistance, composite effects of weathering steels and local environments in order to select the best weathering steel. For this purpose, exposure tests of several weathering steels were conducted under various environmental conditions. Following findings were obtained: (1) The corrosion rate parameter As could be proportional to the weathering alloy index V and the regional corrosivity index Z. (2) Another corrosion rate parameter Bs could be proportional to log(Z), had almost no relation with V. (3) Specimens with a butt weld joint do not have any significant deterioration but, the existence of weldment increased As about 20%. And, (4) Rainfall effects could be explained as modification factor for As and the factor related with index Z. Based on these facts, the index V can be used to select adequate weathering steel if design period, allowable thickness reduction and index Z were given.
