TY - THES

T1 - Accelerated cooling of heavy steel plates - selected aspects of modelling

AU - Kaltenbrunner, Thomas

N1 - embargoed until 11-09-2019

PY - 2014

Y1 - 2014

N2 - Heavy steel plates are used in a wide range of technical applications, for example in plant and construction engineering. Basically, the manufacturing process involves four steps: heating, thermo mechanical rolling, accelerated cooling and levelling. During the accelerated cooling process, a phase transformation takes place. Associated with this phase transformation, transformation induced plasticity (TRIP) occurs. TRIP is strongly affected by the thermo-mechanical history of the material. One major aim of this diploma thesis is to describe the influence of plastic pre-deformation due to the hot rolling process on TRIP. It presents a phenomenological model to modify the well-known Leblond rule by the use of the second and third invariant of the deviatoric stress tensor. This model is capable to yield anisotropic TRIP strains in the tension and compression regime according to observations from dilatometer experiments. Experimental data from a dilatometer are used to adjust material parameters of the new model. The anisotropic TRIP- model is implemented in an ABAQUS user subroutine. Another aim is to correlate the results of 3D- and 1D- finite element models (FEM). Both models allow making predictions of the plate flatness during as well as at the end of the accelerated cooling process. The advantage of the 1D-model is the computational efficiency. The 1D-model considers all influences throughout the plate thickness direction. The 3D-model additionally incorporates effects of lateral dimensions. In order to combine the benefits of both models a correlation between the 1D- and 3D-model is necessary. This work presents algebraic equations to correlate both models. To this end an intensive parametric study with both models has been performed. Finally the correlation function has been tested for arbitrary cases.

AB - Heavy steel plates are used in a wide range of technical applications, for example in plant and construction engineering. Basically, the manufacturing process involves four steps: heating, thermo mechanical rolling, accelerated cooling and levelling. During the accelerated cooling process, a phase transformation takes place. Associated with this phase transformation, transformation induced plasticity (TRIP) occurs. TRIP is strongly affected by the thermo-mechanical history of the material. One major aim of this diploma thesis is to describe the influence of plastic pre-deformation due to the hot rolling process on TRIP. It presents a phenomenological model to modify the well-known Leblond rule by the use of the second and third invariant of the deviatoric stress tensor. This model is capable to yield anisotropic TRIP strains in the tension and compression regime according to observations from dilatometer experiments. Experimental data from a dilatometer are used to adjust material parameters of the new model. The anisotropic TRIP- model is implemented in an ABAQUS user subroutine. Another aim is to correlate the results of 3D- and 1D- finite element models (FEM). Both models allow making predictions of the plate flatness during as well as at the end of the accelerated cooling process. The advantage of the 1D-model is the computational efficiency. The 1D-model considers all influences throughout the plate thickness direction. The 3D-model additionally incorporates effects of lateral dimensions. In order to combine the benefits of both models a correlation between the 1D- and 3D-model is necessary. This work presents algebraic equations to correlate both models. To this end an intensive parametric study with both models has been performed. Finally the correlation function has been tested for arbitrary cases.

KW - Umwandlungsplastizität

KW - Grobblech

KW - Finite Elemente

KW - Materialmodellierung

KW - Transformation Plasticity

KW - Heavy steel plate

KW - finite elements

KW - material modelling

M3 - Diploma Thesis

ER -