Hot deformation behavior and processing maps for coiled tubing steel

Abstract

Hot compression test of coiled tubing steel is performed on Gleeble3500 at 850–1100°C and strain rate from 0.001s−1 to 5s−1. It is found that the flow stress behavior is described by the hyperbolic sine constitutive equation in which the average activation energy of 390kJ/mol is calculated. And the hot deformation behavior of coiled tubing steel is characterized by using processing maps developed on the basis of the dynamic materials model. The processing map shows the flow instable region and the flow stable region. The dynamic recovery (DRV) and dynamic recrystallization (DRX) occur in the stable region. In the processing map, the variation of the efficiency of the power dissipation is plotted as a function of temperature and strain rate. According to the processing map, the coiled tubing steel is rolled by the Thermo-Mechanical-Control-Process (TMCP), and finally it is obtained that the yield strength and tensile strength of coiled tubing steel are 565MPa and 685MPa respectively, and the elongation percentage is 32.1%.