Abstract
This paper deals with the detection of small fatigue cracks by the nondestructive tests in unpainted weathering steel welded joints after 10-year of atmospheric exposure. The nondestructive tests were carried out to find small cracks before and after the rust removal. The detectable limits of fatigue crack depth with or without the rust were 1.2mm by the magnetic particle test and 0.9mm by the eddy current test. The ultrasonic test was not applicable, when the test was carried out over the patina of about 0.1mm.
