中文摘要：

落锤撕裂试验（DWTT）断口形态是油、气管线钢管断裂控制的重要表征。确定应力状态、服役温度和材料结构对X100钢管DWTT断口形态的影响规律,建立DWTT断口形态与X100钢管断裂行为之间的关系,对X100钢管的断裂控制和服役安全具有重要意义。采用DWTT对比研究了人字形和压制V形两种不同缺口类型下,X100钢管母材和X100焊缝两种材料在系列温度下的断口形貌,探讨了缺口类型、材料、温度对DWTT断口形态的影响。结果表明：与压制缺口试样相比,人字形缺口试样的断口有较多的起裂解理和断口分离,较少的逆向解理断裂、延性断裂和剪切唇;与室温相比,低温断口有较多的起裂解理,较少的延性断裂和剪切唇,同时,随着试验温度的降低,断口分离长度和逆向解理断裂面积呈先增大后减小的变化趋势;与焊缝相比,母材断口有较少的起裂解理和逆向解理,较多的延性断裂和剪切唇,断口分离发生于母材中。

英文摘要：

The drop weight tear test（DWTT） notch shape is a critical character to identify if any fracture exists in oil and gas pipe steels. To control the fractures and ensure the operation safety of X100 steel pipes, it is essential to determine the effects of stress state, operating temperature and material texture on DWTT notch shape of X100 steel pipes and confirm the relationship between such notch shape and fracture behavior. This paper, through a DWTT, compares the notch shapes of X100 steel pipe base material and X100 weld under a series of temperatures, considering two notch types（herringbone notch and pressed V-notch）, and discusses the effects of notch type, material and temperature on DWTT notch shape. The results show that, in contrast to pressed V-notch specimen, the herringbone notch specimen presents more fracture cleavages and notch separations, and less reverse cleavage fractures, ductile fractures and shear lips. Moreover, the notch specimen has more fracture cleavages and less ductile fractures and shear lips at low temperature than that at ambient temperature. As the test temperature decreases, the length of notch separation and area of reverse cleavage fracture increase and then decrease. Additionally, the base material shows less fracture cleavages and reverse cleavages and more ductile fractures and shear lips than the weld; notch separation occurs in the base material.