Research on Low-temperature DWTT of 33mm Thick-wall X80 Pipeline Steel Plate

The shear area of low-temperature DWTT of thick-wall X80-grade pipeline steel plate is now becoming a high technical challenge.In the paper,based on alloying design, 33 mm thick-wall X80 pipe line steel plates were obtained through different thickness of inter-mediate bar from non-recrystallization austenite region rolling when the other processing parameters of TMCP（thermo mechanical control process） maintained same values.The micro-structures and properties of resulted plates were investigated and analyzed by means of optical microscope.Comparing the microstructures obtained by the two different rolling processes,it is founded out that increasing thickness of intermediate bar from non-recrystallization austenite region（before starting finishing rolling） can enhance the volume fraction of ferrite and obtain smaller ferrite grains,thus can increase the shear area percent（SA%） of low-temperature DWTT and toughness.