Abstract
Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary HSLA steel plates utilized for gas and oil pipeline production. The strength and crack resistance of pipeline steels are mainly determined by its microstructure and crystallographic texture. In this study, the influence of the structural and textural states of industrially produced API-5L X70-X80 pipeline steels on tensile mechanical properties was analyzed. TMCP routes with different hot rolling temperatures and cooling rates were employed. The texture of steel was assessed using the Taylor factor, which was calculated based on electron backscatter diffraction (EBSD). The decrease in rolling temperature resulted in the sharper texture characterized by {001} planes banding (cleavage planes in the bcc lattice) parallel to rolling direction. The tensile deformation behavior at the stage of necking was determined by the crystallographic and morphological texture of the material and demonstrated significant anisotropy. Rupture of all investigated samples was accompanied by the development of splitting on the fracture surface. The splitting was localized in the rolling plane similar to the splitting in standard Charpy tests of pipeline steels.
Highlights
Publisher’s Note: MDPI stays neutralQuality of life improvement and intensive industrial manufacturing development require large amounts of energy carriers, such as hydrocarbons
scanning electron microscopy (SEM) microstructure demonstrates areas elongated in rolling direction (RD) (Figures 2 and 3) for all Thermo-mechanical controlled processing (TMCP) routes with the exception of a high-temperature route 1
Lowering the controlled rolling temperature and increasing the cooling rate were accompanied by a significant sharpening of the (223)[2−52], (221)[−1−14] orientations; Orientation-averaged Taylor factor correlates with the plate yield stress measured in the transverse direction
Summary
Publisher’s Note: MDPI stays neutralQuality of life improvement and intensive industrial manufacturing development require large amounts of energy carriers, such as hydrocarbons. Trunk pipelines are often employed to deliver hydrocarbons from distant reservoirs often distinguished by adverse climatic conditions [1,2]. One of the most promising ways to increase cost efficiency of trunk pipelines is to increase their operation pressure by using high-strength steel capable of operating in adverse climatic conditions [3,4,5,6,7,8]. Contemporary low-carbon steels and a specific industrial method of their processing, that comprises controlled hot-rolling and adjustable accelerated cooling (thermomechanical controlled processing—TMCP), are used to obtain the required levels of mechanical properties in steel plates designed for natural gas and crude oil pipeline production [4,8,9,10,11,12,13,14,15,16].
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