关键词：涂料；耐腐蚀；损害；钢铁
摘 要：Illinois, like many other large states, has several microclimates where temperature and rainfall can vary. These variations can affect the corrosion rates of sign and signal structures, light poles, and other highway structures. Each atmospheric zone, whether they are rural, semirural, suburban, industrial, or marine areas, may be subjected to salt fall or salt spray, which can affect metals or coatings after prolonged exposure. These highway structures are typically fabricated from weathering steel, galvanized steel, painted steel, or aluminum. Each of these metals and their coatings bear a fabrication cost and have distinct ranges of durability in different atmospheres. Rural and semi-rural atmospheres cause the least corrosion damage to metal and coated surfaces. Suburban environments generally have moderate effects, compared to industrial and saline areas, which have the most corrosive atmospheres. Weathering steels have greater durability in moderate and many industrial atmospheres compared to carbon steels, such as ASTM A36 or SAE 1020. The cost differences between ASTM A36 and ASTM A588 vs. the ASTM A710 Grade 50 steel described in this report are small. Based on data obtained from WorldSteelPrices.com, as of July 2013, the price of ASTM A36 was about $0.295 per lb compared to $0.340 per lb for ASTM A588. Because A710 has slightly higher nickel and copper contents than A588, its cost is estimated to be about $0.36 per lb, based on a metric tonne.