Study on Microstructure and Mechanical Properties of TMCP-UFC-LT Treated Low Ni Steel

The microstructural evolution of TMCP-UFC-LT treated low Ni steel was studied. The results show that the tempered microstructure includes intercritical ferrite, tempered martensite and reversed austenite. Alloy element partitioning occurs during the intercritical holding, and austenite stabilized elements are eventually enriched in reversed austenite. The acicular reversed austenite can arrest the crack tip, hinder the crack propagation, and can improve cryogenic toughness more effectively. Proper dispersion and stable acicular reversed austenite, and fine grains are the main reasons for good mechanical properties of TMCP-UFC-LT treated low Ni steel.

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