某船用钢动态断裂行为的温度效应

在高加载速率条件下,利用Hopkinson杆型动态断裂韧度测试装置测定了某船用钢在不同温度下的动态断裂韧度,首次获得了该钢动态断裂韧度随温度的变化规律,即随着温度降低,动态断裂韧度呈现明显的上下平台及韧脆转变特征.断口形貌则由上平台的微孔型延性断口、韧脆转变区的混合断口过渡到下平台的解理断口.同时,测定的动态断裂韧度值也为该钢在高加载速率条件下的韧脆转变行为及安全性评定提供了定量依据.

TEMPERATURE EFFECTS IN THE DYNAMIC FRACTURE BEHAVIORS OF SHIP-BUILDING STEEL

At different temperatures the dynamic fracture toughness of a ship-building steel was tested and measured using the Hopkinson bar testing equipment. The rule of transition of dynamic fracture toughness versus temperature was first obtained, and the morphology of dynamic fracture at different temperatures was analyzed. Under a high loading rate, the characteristic of transition rule of dynamic fracture toughness versus temperature shows an upper and a lower shelf, and shows the sharp characteristics of ductile-brittle transition for the steel. With decreasing temperature the appearance of fracture of the steel is one of micro void coalescence, and then it has mixed cleavage and cleavage. The security assessment and the behavior of ductile-brittle transition of the steel were obtained quantitatively.