Abstract
Reversed tortional fatigue test of sandglass type specimen with a small flat surface notch was conducted at room temperature for a pure iron and a reduced activation ferritic steel F-82H in a solenoid coil cooled by water. Specimen was not constrained lonitudinally to avoid the additional stress induced by magnetostriction. Magnetic flux density in specimen, about 0.7 Tesra, was in rotation magnetization condition. Initiation and propagation behavior of large number of small cracks were observed on the flat surface notch by using image processing technique. For pure iron, crack initiation became earlier and crack growth faster in magnetic field. For F-82H steel influence of magnetic field did not observed.
