Materials Performance

DEC 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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46 DECEMBER 2018 W W W.MATERIALSPERFORMANCE.COM MATERIALS SELECTION & DESIGN W The changes of stress corrosion crack- ing (SCC) behaviors in simulated industrial atmospheric environments between weathering steel, 09CuPCrNi, and its welded joints were studied by slow strain rate testing, and compared with that in 3.5% sodium chloride (NaCl) solution. The results show that there is no signi€cant tendency to SCC whether before or after welding and exposure to 3.5% NaCl solution. However, in a simulated industrial atmospheric environment, the weld- ing increases the sensitivity to SCC of weathering steel, and the welded joints present an obvious tendency to SCC. Weathering steel has been widely used in railways, vehicles, bridges, architecture, and other areas and it is one of the main structure materials that prevents corrosion in atmospheric environments. The usual weathering steel is a term applied to a car- bon steel base that is primarily alloyed with Cu, P, Cr, Ni, and other elements. The alloy- ing elements can help the steel form a dense innercorrosionlayer, which can stop or slow down the corrosivemedium in the atmosphere from further corroding the material. 1-5 Industrial atmospheric environments with a presence of sulfide differ from those industrial atmospheric environments that Stress Corrosion Cracking Behaviors of Weathering Steel Welded Joints LIHUA GONG, School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, China do not. Sulfide, where present, can convert to sulfurous acid (H 2 SO 3 ) when water is absorbed and could be further oxidized to sulfuric acid (H 2 SO 4 ). Hydrogen ions in H 2 SO 3 and H 2 SO 4 not only accelerate the general corrosion of the material, but more importantly, may havea significant inf lu- ence on stress corrosion cracking (SCC), especially on th e welded joints w hose microstructure has changed. To date, related research efforts mainly concentrat e on tw o asp ects. Th e f irst focuses on the general corrosion law of weathering steel in industrial atmospheric environments, such as general corrosion rate, corrosion product type, the influence of alloying elements, and so on, and are based on laboratory simulations and on- sitetests. 6-7 The other area of focus is on the SCC behaviors of alloy steel and its welded joints in the petroleum and gas industrial environment containing hydrogen sulfide (H 2 S). 8-11 The slightly acidic environment caused by air pollution differs from the H 2 S environment, and less work has been done to investigate the influence of this kind of environment on SCC behavior of weather- ing steel, especially the welded joints with weld defects. There is a lack of concern about the risk of SCC with these materials. Material and Method This work takes 09CuPCrNi as a typical weathering steel, in 0.01 mol/L (0.052%) sodium bisulfite (NaHSO 3 ) solution to sim- ulate the polluted industrial atmospheric

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