| Summary: | The microstructure and properties of as-cast 30Mn steel with and without adding rare earths were systematically investigated. The microstructure was characterized by optical microscopy and scanning electron microscopy combined with energy-dispersive spectroscopy. The addition of rare earths could improve the cast structure. The austenitic transformation of the two steels was studied by differential scanning calorimetry. The onset and finish temperature of austenite increased, and the relative content of ferrites and pearlites changed. Rare earths, when added, improved the strength and plasticity, and increase the impact toughness by 31.3%. The heat deformation behavior was analyzed by using a Gleeble-3500 thermo-mechanical simulator. The onset of dynamic recrystallization was delayed, and the hot deformation microstructures were refined.
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