Long-term corrosion behavior of martensitic steel welds in static molten Pb–17Li alloy at 550 °C

•Corrosion of CLAMs weldments showed a nonlinear relationship with time.•Corrosion pits, grooves and jagged traces and their formation mechanisms are developed.•Corrosion occur because the attack on grain boundaries and elements dissolution.

The corrosion behavior of 9Cr-based martensitic steel weldments was investigated in static molten Pb–17Li at 550 °C for 3000 and 5000 h. Microscopic investigation of corroded surfaces revealed corrosion pits, grooves, jagged traces and their formation mechanisms are developed. Variations in surface composition as a function of exposure time were detected. The weight loss, hardness and corrosion rate increase as exposure time increases. The corrosion rate was affected significantly by concentration of Cr near weld surface. The corrosion mechanism is attributed to the corrosive attack on the grain boundaries and preferential dissolution of the main elements from various phases in microstructure.