Control of HFW Linepipe Yield Strength Ratio and Related Discussion

The strengthening mechanism of the linepipe steel is briefed. The results of the tensile tests as made to the HFW linepipe with different methods are analyzed,and the yield strength ratio of the longitudinal specimen is compared with that of the transversal specimen. It is regarded via the analysis that compared with the specimen for the expanding-ring test,the plate specimen is employed for testing the tensile property of the HFW linepipe,resulting in relatively scattered yield strength and yield strength ratio data,which is related to the hardening effect as produced when processing the plate specimen,but only so slightly affects the deformation-resistance of the material. Along with the increase of the HFW linepipe’s strength,the yield strength ratio is a little bit increased. The pipe’s longitudinal yield strength ratio is higher than the transversal yield strength ratio,and the difference between the two is increased along with the increase of the D/S ratio of the linepipe.