Research on Extrusion Texture and Pitting Corrosion of D16T Drill Pipe in 3.5% KCl Solution

Al alloys have emerged as promising alternative materials for drill pipes in deep and ultradeep wells due to their low densities and high specific strengths. To investigate the relationship between extrusion texture and pitting corrosion, the texture of a D16T Al alloy drill pipe (ADP) in the extrusion direction was examined using electron backscattered diffraction analysis. The pitting depths on the D16T samples were determined through an immersion method with 3D microscopy. Additionally, the adsorption energies of Cl- on the crystal faces (100), (110), and (112) were computed using Materials Studio software in a 3.5% KCl solution at 30, 60, 90, and 120 degrees C. In this study, D16T ADP predominantly exhibited a {112} <111> Cu-type texture oriented along the extrusion direction. Notably, when the solution temperature was constant, the adsorption energy of Cl- peaked on the (112) crystal face. The adsorption energies of Cl- on the (100), (110), and (112) surfaces decreased with increasing temperature, except at 60 degrees C. Furthermore, the analysis revealed general increases in the pitting corrosion densities on D16T samples with increasing temperature, except at 60 degrees C. Conversely, the depths of corrosion pits on the D16T samples decreased with increasing temperature, except at 30 degrees C.