Effect of Yield Ratio on Properties of X80 Steel

The property difference of five kinds of X80 steels with different yield ratios adopted in the 2nd WEGP was investigated through the simulation of general supported load condition of the pipeline by static tensile test,dynamic impact test and hydraulic burst test.The effect of yield ratio on the deformability and pressure-containing capability was analyzed.The results show that the yield ratio had no evident influence on mechanical properties of the X80 steel,and the effect of yield ratio on stress-strain behavior of transverse was much greater than that of longitudinal direction.The yield ratio could reflect the deformability of the material.The transverse yield ratio did not correspond to the longitudinal yield ratio.The transverse yield ratio index specified in technical standards of 2nd WEGP was reasonable.The hydraulic burst pressure of the tested pipes greatly exceeded the minimum of the theoretical calculation pressure,which could ensure the safety of the pipeline.The relation between yield ratio and pressure-containing capability of high strength pipeline steel needed to be investigated further.