Effects of Potential on 508III-52M-690 Dissimilar Weld Joint

doi:10.16183/j.cnki.jsjtu.2018.04.009

Abstract

Abstract: Effect of applied potential on stress corrosion cracking (SCC) behavior of 508III-52M-690 dissi-milar weld joint of safe-end was researched with slow strain rate tensile (SSRT) tests and high temperature electrochemistry tests in high temperature (300℃) water containing 50mg/kg chloride. The results revealed that the SCC susceptibility increases dramatically with the applied potential, then the potential above a critical value exists between －500 and －400mV (versus standard hydrogen electrode). The SCC susceptibility is low and no obvious intergranular or transgranular stress corrosion cracks can be found when the applied potential below the critical value which corresponds to deoxygenated water chemistry. It means the fracture is dominated by mechanical properties and closely relates to the hardness distribution of welded joint. The lower the hardness is, the more easily fractures occur. Therefore, all ductile fractures are located at 52Mb (butt welded) with the lowest hardness. While, when electrode potential is higher than the critical potential, all brittle fractures are located at 508III heat affected zone (508III HAZ) with the lowest corrosion resistance, where exhibits significant SCC behavior with large area intergranular and transgranular stress corrosion cracks. Hence, the dissolved oxygen concentration need be controlled strictly to make sure the corrosion potential is below the critical potential. Besides, the 52Mb and 508III HAZ of this dissimilar weld joint are the most venerable sites to crack which need to be paid high attention to during the operation.

Key words: 508III-52M-690 dissimilar weld joint, stress corrosion cracking (SCC), slow strain rate tensile (SSRT), high temperature electrochemistry

CLC Number:

TL 341

WANG Jiamei1，SU Haozhan1,HE Kun2，ZHANG Lefu1. Effects of Potential on 508III-52M-690 Dissimilar Weld Joint[J]. Journal of Shanghai Jiaotong University, 2018, 52(4): 447-454.

References

［1］HWANG S S. Review of PWSCC and mitigation management strategies of Alloy 600 materials of PWRs［J］. Journal of Nuclear Materials, 2013, 443(1/2/3): 321-330. ［2］SERIES I N E. Stress corrosion cracking in light water reactors: Good practices and lessons learned. No. NPT-3.13［M］. Vienna: International Atomic Energy Agency, 2011. ［3］XU H, MAHMOUD S, NANA A, et al. A new modeling method for natural PWSCC cracking simulation in a dissimilar metal weld［J］. International Journal of Pressure Vessels and Piping, 2014, 116 (4): 20-26. ［4］KANG S S, HWANG S S, KIM H P, et al. The experience and analysis of vent pipe PWSCC (primary water stress corrosion cracking) in PWR vessel head penetration［J］. Nuclear Engineering and Design, 2014, 269(4): 291-298. ［5］DU D, CHEN K, YU L, et al. SCC crack growth rate of cold worked 316L stainless steel in PWR environment［J］. Journal of Nuclear Materials, 2015, 456: 228-234. ［6］BOSCH R W, FRON D, CELIS J P, Electroche-mistry in light water reactors: Reference electrodes, measurement, corrosion and tribocorrosion issuesed［M］. New York: CRC Press, 2007. ［7］ANDRESEN P L, MARTIN M M, AHLUWALIA K. SCC of alloy 690 and its weld metals in high temperature water［C］∥Busby J T, Proceedings of the 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors. Cham: Springer, 2011: 161-178. ［8］KANE R D. Slow strain rate testing for the evaluation of environmentally induced cracking［M］. Philadelphia: ASTM International, 1993. ［9］BERTINI L, SANTUS C, VALENTINI R, et al. New high concentration-high temperature hydrogenation method for slow strain rate tensile tests［J］. Materials Letters, 2007, 61(11): 2509-2513. ［10］MTHIS K, PRCHAL D, NOVOTN R, et al. Acoustic emission monitoring of slow strain rate tensile tests of 304L stainless steel in supercritical water environment［J］. Corrosion Science, 2011, 53(1): 59-63. ［11］LONG B. DAI Y, BALUC N. Investigation of liquid LBE embrittlement effects on irradiated ferritic/martensitic steels by slow-strain-rate tensile tests［J］. Journal of Nuclear Materials, 2012, 431(1): 85-90. ［12］彭德全, 胡石林, 张平柱, 等. 氧氯协同对304L不锈钢在高温高压硼锂水中应力腐蚀开裂的影响［J］. 稀有金属材料与工程, 2014, 43(1): 178-183. PENG Dequan, HU Shilin, ZHANG Pingzhu, et al. Effect of oxygen and chloride cooperation on stress corrosion cracking of 304L stainless steel in high temperature and high pressure water containing boric acid and lithium ion［J］. Rare Metal Materials and Engineering, 2014, 43(1): 178-183. ［13］INDIG M E. 1990 speller award lecture: Technology transfer: Aqueous electrochemical measurements room temperature to 290 ℃［J］. Corrosion, 1990, 46(8): 680-686. ［14］LIN C C, SMITH F R, ICHIKAWA N, et al. Electrochemical potential measurements under simulated BWR water chemistry conditions［J］. Corrosion, 1992, 48(1): 16-28. ［15］SHOJI T, TAKAHASHI H, AIZAWA S, et al. Effects of sulfate contamination, sulfur in steel and strain rate on critical cracking potential for SCC of pressure vessel steels in pressurized high temperature waters［C］∥Theus G J. Proceedings of the Third International Symposium on Environmental Degradation of Materials in Nuclear Power Systems. Pennsylvania: The Metallurgical Society, Inc, 1988: 251-258. ［16］ZHOU X Y, CHEN J. Stress corrosion cracking of iron base alloys in high temperature water［C］∥Theus G J. Proceedings of Eighth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems. Illinois: American Nuclear Society, 1997: 953-959. ［17］ANDRESEN P L, YOUNG L M. Characterization of the roles of electrochemistry, convection and crack chemistry in stress corrosion cracking［C］∥Airey G, Andresen P, Brown J. Seventh International Symposium on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors. Houston, TX: NACE, 1995: 579-596. ［18］ANDRESEN P L, MORRA M M. IGSCC of non-sensitized stainless steels in high temperature water［J］. Journal of Nuclear Materials, 2008, 383: 97-111. ［19］FORD F P. Quantitative prediction of environmentally assisted cracking［J］. Corrosion, 1996, 52(5): 375-395.