Ductile-brittle Transition Temperature of Typical Pipelines in Gas High Pressure Station and Its Influence Factors

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.