日本金属学会誌

J. Japan Inst. Metals, Vol. 74, No. 9 (2010),
pp. 559-564

Acoustic Emission Properties of Corrosion Pitting in SUS304 Stainless Steel during MgCl2 Droplet Corrosion Testing

Mitsuharu Shiwa1, Kaita Ito1, Hiroyuki Masuda1, Hisashi Yamawaki1, Yoshitaka Adachi1, Mayumi Ojima1 and Manabu Enoki2

1National Institute for Materials Science, Tsukuba 305-0047
2Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8685

Abstract:

Acoustic emission (AE) monitoring for corrosion of small chloride droplet was proposed to investigate its mechanism. The corrosion testing in thin plate specimens of SUS304 stainless steel was conducted on an AE waveform measurement system with a high sensitivity AE sensor. Three types of corrosion were observed in the corrosion testing, which were the open pitting, covered pitting and snake-like corrosion, respectively. There were many AE events in the covered pitting and the snake-like corrosion. On the contrary, there was no AE event in the open pitting. Besides, the cross section of the snake-like corrosion was analyzed by EBSD. It shows that there were some cracks at the {111} interface of Σ3 coincidence boundary and annealing twins under the corrosion surface. Therefore, it can be concluded that the detected AE signals of corrosion testing were mainly attributed to the cracking in the covered pitting and the snake-like corrosion.


(Received 2010/4/27)

Keywords:

corrosion, droplet, SUS304, acoustic emission, cracking


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