Application of magnetic phenomena to analysis of stress corrosion cracking in welded part of stainless steel

Stress corrosion cracking (SCC) failures have been reported in many nuclear power plants for the past few years. It is desirable to be able to detect SCC cracks easily and nondestructively before or just after crack initiations for maintaining the integrity of the aged plants. In this study, a new magnetic nondestructive method to detect initial SCC cracks is proposed. The materials are Inconel 600 alloy and type 304 stainless steel which are representative structural materials in nuclear power plants. The change of magnetic flux density due to SCC was measured by flux gate sensors. Moreover, magnetic microstructures near SCC cracks were revealed by magnetic force microscopy observation. The obtained results show availability of the proposed method.