Modeling Microstructure Evolution in a Martensitic Stainless Steel Subjected to Hot Working Using a Physically Based Mod
- PDF / 1,498,861 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 22 Downloads / 239 Views
UCTION
IN order to obtain the optimum process parameters in hot working, a precise prediction of flow stress within all stages of the process is necessary. Although empirical or semi-empirical models were developed for this purpose,[1–5] most of them have limitations. These models are basically appropriate for one or few special grades and usually, with any change in the process, their accuracy will decrease dramatically. To overcome this problem, physically based models have been developed and used for many cases to cover a wider range of operations and materials.[5–11] One approved example of these physically based models which the current work is based on was originally developed by Siwecki and Engberg[9] and NIMA SAFARA is with the Department of Material Science, Dalarna University, 79188, Falun, Sweden and also with the Department of Material Science and Engineering, KTH Royal Institute of Technology 10044, Stockholm, Sweden. Contact e-mail: [email protected] GO¨RAN ENGBERG is with the Department of Material Science, Dalarna University. JOHN A˚GREN is with the Department of Material Science and Engineering, KTH Royal Institute of Technology. Manuscript submitted June 21, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS A
expanded further for different materials and processes. The model was successfully applied to various types of steels including micro-alloyed, CMn, and austenitic stainless steels.[12,13] In this work, the behavior of a martensitic stainless steel during a series of hot compression tests was predicted by modifying the model and adjusting related variables. Using the model, grain growth, flow stress, recrystallization, and relaxation were simulated and the relevant variables for this alloy are found and will be used for future simulations of any hot working process. Except for the few material parameters that were adjusted for this new material and will be explained in the model chapter, rest of the parameters were kept unchanged from the previous works.[12,13] A major assumption in the modeling is that the precipitate structure does not change during the short time of deformation, i.e., the fraction and size of second phase particles will remain constant. The ratio of fraction and size is thus considered as an adjustable parameter and will be evaluated from the experiments. The experimental part of the work was carried out through a series of hot compression test in a Gleeble thermo-mechanical simulator machine and Thermo-Calc software[14] was used to generate the necessary thermodynamic data for modeling.
II.
THE MODEL
In order to develop a powerful tool for predicting and controlling microstructure evolution during a metal working process, it is necessary to have a good process model. For this purpose, a microstructure model was programed in the form of a MATLAB toolbox. This model and its calculation foundations have been described very well elsewhere.[12] Therefore, only the important aspects and adjustments that were implemented for this alloy will be summarized here. The present model is a proce
Data Loading...
