Nondestructive evaluation by eddy current and ultrasonic technique of 475�C embrittlement effects in dss duplex stainless steels and corrosion behavior

Abstract

In this paper, a non-destructive evaluation of the embrittlement effect in duplex stainless steel DSS 2205 aged from 5 h to 100 h at a temperature of 475 ° C was performed by Eddy current and ultrasonic techniques, in addition the corrosion behavior was carried out after heat treatment at 475°C. The experimental results show that an inverse behavior was observed between normalized impedance and hardness in aging time at 475°C; when the normalized impedance of the Eddy current probe was decreased, hardness was increased with aging time. The longitudinal ultrasonic velocity and transversal velocity were calculated in this study for each sample. The Young’s modulus and the Shear modulus were computed from the two velocities. The investigation carried out shows a sensitivity of Eddy current and ultrasonic technique to the microstructure changing observed at 475 ° C, due to embrittlement in duplex stainless steel. The effect of heat treatment at 475°C on the corrosion behavior was also evaluated by Eddy current on a long time and revealed the important changing in corrosion resistance due to spinodale decomposition of the ferrite phase.