Hot Deformation Behavior and Constitutive Modeling of High Strength Low-Carbon Alloyed Steel Manufactured by Wire and Arc Additive Manufacturing

For additive manufactured metal components, the application of plastic deformation contributes to improving mechanical properties. Therefore, a fundamental understanding of material flow behavior is crucial for designing a hot working process. In this study, the isothermal compression experiments over the deformation temperature range of 850-1150 degrees C and strain rate range of 0.01-10 s-1 were conducted to investigate the deformation behavior of high strength low-carbon alloyed steel manufactured by wire and arc additive manufacturing (WAAM). The results indicate that the deformation behavior of the material at elevated temperatures is determined by the interplay of strain hardening, dynamic recovery and dynamic recrystallization. The strain-compensated Arrhenius-type model and modified Fields-Backofen model were developed to describe the flow behavior. The coefficients of Arrhenius phenomenological constitutive equation were determined by the linear regression analysis and nonlinear fitting method, respectively. To evaluate the predictability and adaptability of these models in describing the flow behavior during hot deformation, standard statistical parameters including the relative coefficient R, the average absolute relative error AARE and the average root mean square error RMSE were utilized. Comparatively, Arrhenius-type model adopted the nonlinear fitting method shows the superior capability of characterizing the complex flow behavior over the whole deformation stage. The corresponding values of R, AARE and RMSE are 0.99125, 3.365% and 5.315 MPa, respectively. According to the thermal processing maps, the optimized processing window is in the temperature range of 980-1150 degrees C and strain rate range of 0.01-0.4 s-1.