Abstract
Low carbon high manganese cast steels with various Mn contents were processed by Q, QT and QLT treatments to examine the toughness in V-notched Charpy impact and dynamic fracture toughness tests. For 5%Mn steel, the toughness was improved greatly by the microstructural refinement and the introduction of stable and fine retained austenite during the QLT treatment. The retained austenite is considered to give transformation induced plasticity. For 10%Mn and 15%Mn steels, the QLT treatment did not improve the low temperature toughness because of a large amount of epsilon martensite contained.
The dynamic fracture toughness did not always correspond to the Charpy impact toughness owing to notch tip effect.
