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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49 MATERIALS PERFORMANCE: VOL. 57, NO. 12 DECEMBER 2018 are many defects at the HAZ and weld seam of welded joints, such as coarse grain, min- g lin g, wel din g draw b ack s, etc., w hich increases the general corrosion rate and lowers the dissolution rate in the local anode. However, the forces are dispersed. As a result, although the hardened texture caused by welding increases the sensitivity to SCC, it is not obvious. In contrast, the sensitivity of the welded joint to SCC in 0.052% NaHSO 3 containing hydrogen obvi- ously increases. On one hand, it is because the hardened texture increases the HIC sensitivity. On the other hand, the acicular ferrite transformation can bring about lots of di slocations w h ere hydrogen atoms gather and increase hydrogen absorption. Under the action of external force, hydro- gen follows the movement of dislocations, which has a pinning effect on the disloca- tion and causes local hardening. Further- more, the moving dislocations can pile up when they run into a grain boundary or other obstacles where the hydrogen mole- cule will form and gather. As a result, the internal force produces and increases the stress. That is why the risk of SCC increases in the medium containing hydrogen on the weathering steel welded joint. Conclusions 1. There was not obvious sensitivity of 09CuPCrNi to SCC in neither 3.5% NaCl nor 0.052% NaHSO 3 solution. 2. 09CuPCrNi is composed of polygonal ferrite and pearlite before and after welding. The over-heated texture and acicular ferrite made the hardness of the weld seam and HAZ higher than the base metal. All these show that welding produces a sensitive micro- scopic texture that increases SCC tendency. 3. The sensitivity of the 09CuP CrNi welded joint to SCC in 3.5% NaCl increased slightly compared with the base metal. However, there was still not an obvious SCC tendency. In 0.052% NaHSO 3 , the sensitivity to SCC increased significantly. This is related to the certain media in which the HIC could happen . So the 09CuP CrNi welded joint presented the higher sensitivity to SCC in the industrial atmospheric environment. References 1 T. Nishimura, H. Katayama, K. Noda, et al., "Effect of CO and Ni on the Corrosion Behav- ior of Low Alloy Steels in Wet/Dry Environ- ments," Corros. Sci . 42, 9 (2000): pp. 1,611- 1,621. 2 J.T. Keiser, C.W. Brown, R .H. Heidersbach, " C h a ra c t e r i z a t i o n of t h e Pa s siv e Fi l m Formed on Weathering Steel," Corros. Sci. 23, 3 (1982): pp. 251-259. 3 M. Yamashita, H. Miyuki, Y. Matsuda, et al., " The Long Term Growth of the Protective Rust Layer Formed on Weathering Steel by Atmospheric Corrosion during a Quarter of a Century," Corros. Sci . 36, 2 (1994): pp. 283- 299. 4 S. Hara, T. Kamimura, H. Miyuki, et al., "Tax- onomy for Protective Ability of Rust Layer using its Composition Formed on Weather- ing Steel Bridge," Corros. Sci . 49, 3 (2007): pp. 1,131-1,142. 5 R . Luo, J. Wu, X.L. Liu, et al., "Evolution of Rust Layers Formed on Q235 and 09CuP- CrNi-A Steels during Initial Stage of Field Exposure in Two Sites of Different Environ- ment," J. of Chinese Society for Corrosion and Protection 34, 6 (2014): pp. 566-573. 6 H.Y. Wu, Y.M. Zhao, Z.R. Ai, et al., "Corrosion Behavior of High Strength Weathering Steels in Simulated Industrial Atmosphere Envi- ronment," Transactions of Materials and Heat Treatment 34, 11 (2013): pp. 150-155. 7 X.L. Wang, B. Song, S.L. An, et al., "Corrosion Behaviors of RE Heavy Rail in Simulated Industrial Atmosphere," J. of University of Science and Technolog y Beijing 36, 1 (2014): pp. 72-76. 8 F.Q. ]Bi, X.Y. Zhang, Y. Wang, et al., Research on Stress Corrosion Behavior of X70 Pipeline steel in H 2 S Environment," J. of Materials Engineering 8 (2009): pp. 15-18. 9 L.Y. Xu, H.Y. Jing, J. Cao, et al., "H 2 S Stress Corrosion Investigation of Pipeline Steel Welded Joints," Transactions of the China Welding Institution 31, 1 (2010): pp. 12-16. 10 V. Smanio, M. Fregonese, J. Kittel, et al., "Con- tribution of Acoustic Emission to the Under- standing of Sul┬Ęde Stress Cracking of Low Alloy Steels," Corros. Sci. 53 (2011): pp. 3,942- 3,949. 11 J. Kittel, V. Smanio, M. Fregonese, et al., "Hy- drogen Induced Cracking (HIC) Testing of Low Alloy Steel in Sour Environment: Impact of Time of Exposure on the Extent of Dam- age," Corros. Sci. 52 (2010): pp. 1,386-1,392. 12 GB/T 15970.7-2000, "Corrosion of metals and alloys. Stress corrosion testing. Part 7: Slow strain rate testing (Beijing, China: Metallur- gical Information Standards Institute, 2000). LIHUA GONG is a professor at the Jiangsu University of Science and Technology, Jiangsu Province, China, who conducts research involving corrosion and protec- tion of metal materials. Subscribe to the Maritime Newsletter Visit and click on the Maritime News link to subscribe. Stress Corrosion Cracking Behaviors of Weathering Steel Welded Joints

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