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Fractal characteristics of stress corrosion cracking in SNCM 439 steel having different prior-austenite grain sizes

✍ Scribed by Masashi Kurose; Yukio Hirose; Toshihiko Sasaki; Yasuo Yoshioka


Publisher
Elsevier Science
Year
1996
Tongue
English
Weight
515 KB
Volume
53
Category
Article
ISSN
0013-7944

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✦ Synopsis


An approach by fractal geometry was examined for the SCC problem on a Ni-C~Mo steel.

Stress corrosion tests were conducted in 3.5% NaCI solution by using SNCM439 steel specimens. These specimens had different prior-austenite grain sizes due to variations in heat treatment.

After summarizing the results of analysis, we explain the profiles of stress corrosion cracks having fractal characteristics. The relevant fractal dimension D was about 1.05 for the region where the intergranular cracking was predominant, while D was about 1.10 for the region having mixed fracture of intergranular and transgranular cracking. The fractal analysis concluded that the crack growth rate da/dt depends on the grain size d, but not stress intensity factor K. The investigations of crack growth phenomena were seen to be an important factor to explain the mechanism.