Effect of Metastable Austenite on Mechanical Properties of High-Strength Steel in Oceaneering

doi:10.12068/j.issn.1005-3026.2021.10.005

Abstract

Abstract: The effects of critical annealing and tempering at different temperatures on the microstructure and mechanical properties of marine engineering steels were studied. The results show that the microstructure of the tested steel contains tempered martensite and different volume fraction (0~6%) retained austenite after two-phase zone annealing and tempering at different temperature. When the volume fraction of retained austenite increases from 0 to 6%， the yield strength decreases from 753~506MPa and the tensile strength ranges from 794~843MPa， the yield ratio decreases from 0.9 to 0.6， and the elongation increases from 31.3%~36.2%. The retained austenite in the tested steel can improve the impact work for plastic deformation and hinder the crack propagation. The impact energy at -80℃ reaches 236J. However， due to the poor thermal stability， the retained austenite prefers to transform into martensite at low temperature， leading to a reduction of low-temperature toughness and the impact energy at -80℃ drops to 136J.

Key words: steel for oceaneering; retained austenite; strength; low-temperature toughness; heat treatment

CLC Number:

TG115.5

ZHOU Cheng， LIU Wen-peng， YE Qi-bin， WANG Zhao-dong. Effect of Metastable Austenite on Mechanical Properties of High-Strength Steel in Oceaneering[J]. Journal of Northeastern University(Natural Science), 2021, 42(10): 1400-1406.

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