Vliv vícenásobné plastické deformace na svařitelnost ocelí

Abstract

The presented dissertation deals with the study of weldability of carbon steels after preparation by multiple extreme severe plastic deformation (SPD-Severe Plastic Deformation). The basic procedure for solving the problem is a combination of experimental tests with advanced numerical simulation. The work deals with the influence of welding on the properties of carbon steels processed by multiple severe plastic deformation. The subject of the study are steels S355 and Ck55, which are both widely used in technical practice but differ significantly in carbon content and thus the overall weldability. DRECE (Dual Rolling Equal Channel Extrusion) technology was used as SPD technology 142-GTAW welding technology was used to prepare the experiment. To determine the technological data for numerical simulation, a complete monitoring of welding parameters was performed, including the measurement of temperature cycles. The joints were evaluated by basic mechanical tests and supplemented by metallographic surveys. With regard to the anisotropic state of residual stresses, the deformation cycle was also monitored by analyzing the residual stresses during SPD technology before and after welding. The magnetoelastic method was used for the analysis of residual stresses. In parallel with the experiment, a complete preparation of material and technological data for advanced numerical simulation of DRECE technology and selected welding technologies was performed. The Simufact.Welding and Simufact.Forming programs were used for numerical simulation of welding and forming. A complete numerical simulation of DRECE technology forming in two cycles was performed in the selected software Simufact.Forming. The SPD results of the processed material were used as a starting point for numerical simulation of welding with 142-GTAW and 751-LB technologies. The results of numerical simulations were compared with experimental results.