Papers by Author: Zoltán Dudás

Abstract: The first part of this document demonstrates the creation and use of continuous cooling (CC) diagrams, which are built up from Temperature-time T-t elements. The second part of the document shows the possibility of the creation of virtual CC diagrams by numerical approximated base transformation diagrams, based on measured data.

Abstract: This paper explains and demonstrates an approximation method for the calculation of the stress values depending on the temperature and time, or time values depending on the stress and temperature using time dependent and temperature dependent power functions. The approximation is based on measured data and the paper shows the verification of the power function approximation.

Abstract: This document explains and demonstrates two simple approximation methods based on the Newton formula. The first method makes possible the transformation of whole temperature-time interval diagrams into temperature-time diagrams to help the comparison of the diagrams. The second shows a way how

Abstract: This document shows the equations and some calculation results of two new Diffusion parameters. The Diffusion parameters assist the calculation of different temperature or time values for equivalent diffusion processes. The Diffusion parameters include temperature dependent and temperature independent factors. The document shows that the introduced Diffusion parameter is suitable for the accurate calculations of the temperature and time values for equal simple diffusion processes. The document shows, that the frequently used Larson-Miller parameter (LMP) does not give accurate results if we use the temperature and time values of equal simple diffusion equations for the LMP calculations.

Abstract: The TTT (Time-Temperature-Transformation) phase transformation diagrams based on FEM based phase elements make it possible to create virtual TTT diagrams. In this case the virtual TTT diagrams are results of multiple linear regression calculations. The basic TTT diagrams are created on the basis of measured published data. Two created virtual TTT diagrams are presented for two different austenitisation temperatures. The results of calculations are compared to the measured ones.

Abstract: Knowledge of the TTT (Time-Temperature-Transformation) or CCT (Continuous- Cooling-Transformation) diagrams of steels is an important factor in the thermo-mechanical processing of steels. Much experimental work has been undertaken to determine such diagrams. Significant works have been written which can calculate TTT and CCT diagrams for steels. The aim of the present work is to show the developed model that can provide accurate enough TTT and CCT diagrams for steel 42 CrMo4 (where the austenitisation temperature was 1050°C). The calculated results are compared by the experimental results. The developed TTT phase transformation diagrams based on FEM-based phase elements and the star-like cooling simulation make it possible to create virtual CCT diagram data.

Abstract: The application of the FEM based phase elements is very useful for evaluation of the effects of TTT phase transformations diagrams. The comparison of the different TTT diagrams of the same type of the 50 CrV 4 steels shows that fine differences are possible to be evaluated and approximated by this simulation. Examples are presented for the use of the multiple regression calculation applying the data of the suitable TTT diagrams.