Defect evolution near the crack tip in stainless steel (SUS 304) under tensile stress was observed through in-situ positron microbeam measurements. It was found that the S parameter of the Doppler broadening of annihilation radiation spectrum increased near to the crack tip. Upon the corrosion treatment, the crack progress occurred preferentially in the high S parameter region. The further increase of S parameter due to the complementary influences of tensile stress and corrosion environment was observed at the region away from the progressed crack. These results suggest excess that vacancy type defects play an important role in the stress corrosion cracking of stainless steel.

Evaluation of Stainless Steel under Tensile Stress using Positron Microbeam. M.Maekawa, Y.Yabuuchi, A.Kawasuso: Journal of Physics - Conference Series, 2010, 225[1], 012033