Along with the development of the energy industry, demand for oil and gas pipelines has increased, and as the low oil price era has been prolonged, more economical pipe design and construction are required. Especially, ERW pipe has been expanding its range of applications, which is advantageous in terms of productivity and price. ERW pipes are made by passing through continuous rollers, where unintentional plastic deformation such as the Bauschinger effect occurs. Since plastic deformation caused by repetitive loading and unloading changes the initial properties of steel, it is necessary to precisely predict the final properties of the pipe as well as an accurate understanding of the manufacturing process. So, this study focused on evaluating the effects of manufacturing process considering plastic deformation for high performance ERW pipe manufacturing.
In this paper, three manufacturing process stages of ERW pipe were simulated as 3D nonlinear finite element models using ABAQUS: forming stage, sizing stage, and flattening stage. And the ABAQUS model was verified by comparison with the outer diameter measured from full-scale size pipes. In order to maintain the continuity of analysis between each manufacturing process stage, PEEQ, Alpha and residual stress were obtained from each manufacturing process stage, and then these mechanical properties were mapped to the next manufacturing process stage. And change of mechanical properties during the each manufacturing process stage were examined. Finally, the change of material properties at the flattening stage where reverse bending occurs was evaluated, especially in influence of sizing ratio on the flattening stage. Through the developed analytical model, numerical prediction of the mechanical properties of ERW pipe is possible.