Development Of High Grade Pipeline Steels And Bends Form X70Pipeline Steel

The rapid development of oil and gas transportation, gas pipelines conveyingpressure continues to increase, so that the requirements of the pipe line steels is also rising.Next decade will be the construction of oil and gas pipelines climax period, the estimatedannual pipeline will require more than1million tons. Development of X80pipeline steel,laying the foundation for manufacturing large-diameter high-pressure pipeline steel, sonot only can improve pipeline efficiency, save steel, reducing energy consumption andreduce environmental pollution. In this paper, we make composition design, give full playto the dispersion strengthened alloy elements and control the finishing stages ofdeformation temperature, so that the strain induced precipitation phase particles morediffuse, small deformation induced precipitation of fine precipitates pinning deformedaustenite grain boundaries, and better micro-alloying elements play a strengtheningeffect.Combined with optimized melting process and heat treatment process to obtainhigh-quality X80, X70station steel and hot bends form steel. X80, X70station steel yieldstrength reached556.5MPa and546.7MPa, tensile strength, respectively647.3MPa and637.3Mpa,-40℃Charpy impact energy and411.9J and438.5J. X80hot bends form steelyield strength568MPa; tensile strength reached706MPa; yield ratio performance of0.74-0.88; plate thickness1/2-20℃Charpy range of180-380J, average to282J. And theplate thickness center-20℃Charpy average282J, steel core part has good low temperaturetoughness. X70steel pipe heat simmer mean555MPa; average tensile strength of661MPa.Yield ratio range of0.76-0.90, Plate thickness1/2of-20℃Charpy range of255-465J,average360J. The average yield ratio was0.84, and the plate thickness center-20℃Charpy average360J, steel core part has good low temperature toughness.