Microstructure, microtexture, and crack susceptibility in pearlitic steel during lab-simulated processes aiming tensile armor application in flexible pipelines

Tensile armor is usually made of flat pearlitic steel wires and produced in a manufacturing sequence as follows: hot-rolling → patenting treatment (PT) → cold forming → wire coiling → stress relief → re-winding wire process. To evaluate the effect of the key parameters in this set of processes on the microstructure, microtexture, and crack susceptibility in commercial pearlitic steel, four process routes were lab-simulated with different setups of 45% hot-rolling, PT, and 65% cold-rolling. Subsequently, the cold-rolled specimens produced through the four distinct routes underwent two stress relief treatments (at 400 and 700 °C for 60 s), succeeded by simulation of the re-winding wire process via four alternated three-point bending procedures. Scanning electron microscope images, microhardness, and electron backscattered diffraction techniques were extensively performed in this work. Due to pearlitic block size control, the PT influenced the {111} component formation during the cold-rolling process. During the bending experiments, cracks were detected just in the route with the highest cold-rolled {111} microtexture orientation followed by stress relief at 700 °C. This crack susceptibility was related to the small recrystallized grains nucleated in the shear bands of the {111} pearlitic blocks during the stress relief treatment. •Patenting treatment can change pearlitic block size, colony size, interlamellar spacing, microtexture, and microhardness.•Pearlitic block size affects the intensity of the {111} microtexture component formed during the cold-rolling process.•Stress relief at 700 °C for 60 s can produce small recrystallized grains inside 65% cold-rolled {111} pearlitic blocks.•Small recrystallized grains inside {111} pearlitic blocks are prone to crack nucleation during bending deformation.