Creep is a complex material feature occurring in mechanical structures under moderate stresses and relatively high temperatures. Transformation-induced plasticity (TRIP) is a macroscopic phenomenon of steel behavior. If phase transformations occur under deviatoric stress, a permanent inelastic strain is obtained even if the yield stress is not reached. Thus, creep and TRIP do not have a yield stress like plasticity and visco-plasticity. Sometimes, during heat treatment of steel, creep and TRIP appear together. In order to determine creep or TRIP behavior it is necessary to verify concrete material laws and to determine corresponding material parameters. For this reason, often uniaxial experiments with small probes are performed in special devices. It is the main purpose of this study, to develop a procedure for the verification of possible laws for creep and TRIP and for determining material parameters, using experimental data. Therefore, an implicit algorithm in two variants will be developed: strain-driven and stress-driven. These algorithms can also be applied to simulations of (spatially homogenous) uniaxial experiments. Based on these algorithms, an optimization scheme will be developed for finding material parameters which realize a best approximation. Finally, the developed procedure will be applied for the investigation of creep and TRIP during heating of the bearing steel 100Cr6 (SAE 52100).
Let the evolution equation for ξ bė( 2.22) Differentiating (2.21) with respect to time t and inserting (2.22), one gets (2.17).
This work focuses on phenomena arising during the heating process at the beginning of steel heat treatment. It has been prepared within the Collaborative Research Centre SFB 570 , Distortion Engineering' at the University of Bremen. In order to predict the distortion of steel components during heat treatment, a detailed knowledge of the arising phenomena is crucial. There can arise creep due to the underlying high temperatures as well as transformationinduced plasticity (TRIP) during the austenitisation. This contribution focuses on the modelling of creep, phase transformations and TRIP of 100Cr6 (SAE 52100) steel during heating and austenitisation. The proposed model approaches are verified on the basis of experimental data stemming from uniaxial experiments. We provide material laws of the considered phenomena as well as the evaluation of experimental data. The simultaneous occurrence of creep and TRIP represents a special challenge in the analysis of experimental data as well as in the verification of model approaches.
Some recent developments in modelling of heat-treatment phenomena in steel within the collaborative research centre SFB 570 "Distortion Engineering"Einige aktuelle Entwicklungen in der Modellierung von Phänomenen der Wärmebehandlung beim Stahl im Sonderforschungsbereich SFB 570 "Distortion Engineering"It is the aim to present some developments in modelling of distortion-related phenomena during heat treatment of steel in the context of the Collaborative Research Centre SFB 570 "Distortion Engineering" at the Bremen University, Germany. Taking this into account, a survey will be given and some results will be exemplarily presented. This work is the first contribution to the session "Modelling of material behaviour within the CRC Distortion Engineering" of the 3 Bökenheide et al. 2011 [2] deal in detail with the steel qualities 100Cr6 (SAE 52100) and 20MnCr5 (SAE 5120), respectively. Here, more general aspects of the subsequent phenomena are in the focus: Phase transformations (PT) and transformation-induced plasticity (TRIP) during quenching and heating, plastic behaviour of (supercooled) austenite as well as creep during heating and austenitising. The following items will be considered in particular: Experiments and processing strategies for experimental data, model approaches and results for single phenomena of material behaviour. Many assertions have a general character not linked to special steel sorts. We will also address open questions and possible perspectives.
IntroductionIt is the aim to present the development of modelling of steel phenomena which are relevant to distortion of work-pieces during heat treatment in the context of the Collaborative Research Centre SFB 570 "Distortion Engineering" at the University of Bremen. The main concept of this long-time research project (started in 2001) is a system-oriented view on distortion. For a comprehensive explanation we refer to [3].
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