Abstract: The impact energy distribution law of Q390 low-alloy and high-strength steel in transition temperature region was investigated by using the Charpy impact test， the idea of the Master Curve method and the empirical correlations between impact energy and fracture toughness. The Master Curve reference temperature was obtained by the Charpy impact tests. And then the Master Curve expression of Q390 steel was regressed from the Master Curve reference temperature. Besides， considering the influence of the thickness of impact specimen， the impact-energy principle resembling Master Curve distributive model of Q390 steel in transition temperature region was finally acquired by combining the empirical correlation which was most suitable for Q390 steel. The results show that this model fairly describes the relationship among the impact energy， the temperature and the cumulative failure probability in transition temperature region of Q390 steel， and expands the application of the Master Curve method to a certain extent.

Key words: Q390 steel, impact energy, Master Curve, transition temperature region, Charpy impact test, empirical correlation