Effect of Al Content on Microstructure and Properties of Solid Solution 15-15Ti Steel under Liquid Lead-Bismuth Corrosion Condition

Aiming at the problem of liquid lead-bismuth corrosion faced by structural materials in lead-based fast reactors, 15-15Ti austenitic stainless steel was selected as the research object. The effects of Al content on the microstructure and properties of solid solution samples under liquid lead-bismuth corrosion conditions were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and testing of mechanical properties. The results show that with the increase of Al content, the ferrite precipitation temperature of the steel increased, the austenite precipitation temperature decreased and the ferrite content increased significantly, while the precipitation of σ phase was inhibited. The change trend of mechanical properties of solid solution samples after liquid lead-bismuth corrosion was similar to that of aging samples. With the increase of Al content, the strength of the samples increased and the elongation after fracture decreased. After corrosion for 2 000 h, the elongation of solid solution samples containing 4%(mass fraction, the same below) Al was significantly lower than that of solid solution samples containing 3% Al and 2% Al. Appropriate amount of Al could improve the strength of the steel, but excessive Al content led to embrittlement of the steel. Therefore, the solid solution sample containing 3% Al after lead-bismuth corrosion showed good strength and toughness matching.