通过对北京丰台南次高压站A3钢管和王四营桥高压站20钢管两种管材进行不同温度下的系列冲击试验，对两种管材的韧脆转变温度进行了测定和分析，并结合化学成分及显微组织分析了影响材料低温韧性的因素。结果表明:A3钢管在不同温度下的冲击吸收能量及剪切断面率均小于20钢管的；前者的韧脆转变温度为3.7 ℃，后者为-17.2 ℃；管材的韧脆转变温度受化学成分和显微组织的影响，化学成分中碳、硅、硫、磷元素的含量越低，其韧脆转变温度也越低；铁素体-珠光体钢在晶粒度相同的情况下，钢中铁素体含量越高，其韧脆转变温度则越低。

The ductile-brittle transition temperature of A3 steel pipeline in Beijing Fengtai south sub-high pressure station and 20 steel pipeline in Wangsiying bridge high pressure station was measured and analyzed through series of impact test at different temperatures, and factors affecting the low-temperature toughness of materials were also analyzed combined with chemical compositions and microstructure. The results show that both of the impact absorbed energy and the shear rate of A3 steel pipeline were less than those of 20 steel pipeline, and the ductile-brittle transition temperatures of A3 steel pipeline and 20 steel pipeline were 3.7 ℃ and -17.2 ℃ respectively. The ductile-brittle transition temperature of the pipelines was influenced by chemical compositions and microstructure. The lower the contents of element C, Si, S, P were, the lower the ductile-brittle transition temperature was. For ferrite-pearlite steel pipelines with the same grain size, the higher the content of ferrite in the microstructure was, the lower the ductile-brittle transition temperature was.