Abstract
Residual stresses in components are a central issue in almost every manufacturing process, as they influence the performance of the final part. Regarding hot forming processes, there is a great potential for defining a targeted residual stress state, as many adjustment parameters, such as deformation state or temperature profile, are available that influence residual stresses. To ensure appropriate numerical modeling of residual stresses in hot forming processes, comprehensive material characterization and suitable multiscale Finite Element (FE) simulations are required. In this paper, experimental and numerical investigations of thermo-mechanically processed steel alloy 1.3505 (DIN 100Cr6) are presented that serve as a basis for further optimization of numerically modeled residual stresses. For this purpose, cylindrical upsetting tests at high temperature with subsequently cooling of the parts in the media air or water are carried out. Additionally, the process is simulated on the macroscale and compared to the results based on the experimental investigations. Therefore, the experimentally processed specimens are examined regarding the resulting microstructure, distortions, and residual stresses. For the investigation on a smaller scale, a numerical model is set up based on the state-data of the macroscopic simulation and experiments, simulating the transformation of the microstructure using phase-field theory and FE analysis on micro- and meso-scopic level.
Highlights
During the manufacturing of components, various residual stress states may occur in the material because of the process
Based on data obtained from the experimental and simulative investigations of the previous sections, a numerical model is developed in the following, which accounts for the phase transformation from austenite to martensite (A-M) during rapid cooling and investigates the resulting residual stress distribution on a mesoscopic level
The material behavior of the steel alloy 1.3505 during the thermo-mechanical forming process was investigated by experiments and simulation approaches on different scales regarding microstructural transformation behavior and the resulting residual stresses
Summary
During the manufacturing of components, various residual stress states may occur in the material because of the process. There have been several investigations of the relationship between forming parameters such as deformation state or temperature profile and resulting residual stresses by experiments and simulations; see for instance [1,2,3]. It is noteworthy that the residual stresses resulting from metal-forming processes are generally known to have negative effects, regarding e.g., lifetime, so that avoidance or minimization during the manufacturing process is usually targeted instead of influencing component properties. The resulting mechanical properties of steels strongly depend on the physical processes, e.g., hardening and phase transformations, occurring during the material production and the manufacturing. In the scope of this work, an insight into the experimental and numerical analysis of the material behavior in thermo-mechanical forming processes as well as simulation approaches of residual stresses on different scales is provided.
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