Affiliations: [a] Science University of Tokyo, 1-3 Kagurazaka,
Shinjuku-ku, Tokyo 162-8601, Japan | [b] Former Graduate Student, Science University of Tokyo,
Japan | [c] Graduate Student, Science University of Tokyo, 1-3
Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
Correspondence:
[*]
Corresponding author: Yuji Nakasone, Department of Mechanical
Engineering, Faculty of Engineering, Science University of Tokyo, Kagurazaka
1-3, Shinjuku-ku, Tokyo 162-8601, Japan. Tel.: +81 3 5228 8366; Fax: +81 3 3260
4291; E-mail: nakasone@rs.kagu.sut.ac.jp
Abstract: The present study investigates a method for the non-destructive
detection of damage in an austenitic stainless steel SUS 304 by the use of
martensitic transformation. Volume fraction of α'
martensite transformed in uniformly stretched SUS304 plates was measured and
expressed as a function of the applied strain level
ε. The distributions of α'
phase in the plastic wake regions produced around fatigue cracks were then
electromagnetically measured in fatigued SUS 304 plate specimens. The results
were compared with the distributions of magnetic flux density
B_{z} above the fatigue cracks in the specimens magnetized
by a strong magnetic field higher than 0.4 T. It was revealed that the
B_{z} distributions reflected the α"
phase distributions in the wake regions: i.e., the distance between the points
where B_{z} reached the minimum and the maximum had a high
correlation with the fatigue crack length, and the minimum and the maximum
values of B_{z}showed a linear relationship with the applied
stress intensity factor range ΔK. These results imply
that not only the crack length but also the fatigue damage can be detected
effectively in an electromagnetic non-destructive way.
