Effect of Quenching, Lamellarizing, and Tempering on Reversed Austenite and Cryogenic Toughness of 9Ni Steels.

Herein, the effects of quenching, lamellarizing, and tempering (QLT) on reversed austenite and cryogenic toughness of 9Ni steels were investigated in terms of microstructure characterization, internal friction tests, and low temperature impact tests. The results showed that QLT treatment not only refined the grain effectively, but also promoted the formation of reversed austenite, thus obtaining excellent ultra-cryogenic toughness. Furthermore, QLT treatment promoted the redistribution of C, Mn, and Ni elements, so that more stable austenite was retained to room temperature. The phase transformation peak in the internal friction peak confirmed that QLT treatment effectively promoted the formation of reversed austenite, while the Snoek–Kê–Köster peak showed a strong interaction between carbon atoms and dislocations. Due to the synergistic effect of fine grain toughening and TRIP effect, the 9Ni steel treated by QLT appeared more excellent ultra-cryogenic toughness.Please check and confirm the corresponding author mail id is correctly identified.The corresponding author mail id is correct. [ABSTRACT FROM AUTHOR]