Abstract
The paper deals with mathematical modelling of non-isothermal forging process accounting for the distribution of effective strain, strain rate, temperature and microstructural changes occurring in the deformed material. So far, forging technologies of the investigated alloyed steel grade 16NCD13 have been designed intuitively and applied in practice, but there is still lack of reliable models describing behaviour of this steel during thermomechanical processing. Thus, the general objective of the present work was to develop rheological and microstructure evolution model for the steel under investigation. Uniaxial compression tests were performed in a wide range of strains, strain rates and temperatures. The experimental results, in the form of load vs. displacement measurements, were used as input for the inverse calculations. Rheological models based on flow stress functions of various complexity were determined and validated. It is shown that when the inverse analysis is applied to the interpretation of the plastometric tests, the properties of the material are insensitive to the method of testing and to the sample dimensions. A number of tests with identical deformation conditions and various intervals between deformation and quenching were performed to provide data for identification of the microstructure evolution model. Also stress relaxation technique was used for this purpose. The models were implemented into Forge2008 commercial code for the simulation of industrial forging process. The results of the simulation show good predictive ability of combined thermal-mechanical-microstructure evolution model in hot forging of 16NCD13 steel