Two-dimensional simulation of thermal cutting of low-alloyed steels
Laitinen, Arttu (2015)
Laitinen, Arttu
2015
Konetekniikan koulutusohjelma
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2015-10-07
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201509231601
https://urn.fi/URN:NBN:fi:tty-201509231601
Tiivistelmä
Flame cutting is a commonly used method of thermal cutting, where a controlled flame and oxygen jet are applied to a thick steel plate to burn it and to create a cut edge. This heat from the flame causes significant temperature differences, which induce plastic deformation, phase transformations and residual stresses inside the steel plate. Tensile residual stresses are assumed to be a factor in delayed cracking, which happens when the steel plates are put into storage.
To thoroughly understand and optimize the flame-cutting process for preventing the cracking, more information about the conditions inside the steel plate, while it is being applied with a large amount of heat, is needed. Temperature history is the defining factor to the phase distribution of steel, and creating an optimal microstructure is the desired outcome of every heat-treatment process. By modelling the process, more information about the stress distribution and the temperature history can be obtained.
A model of flame-cutting of low-alloyed steel was made by using a commercial finite element program ABAQUS. First the material was created to resemble the characteristics of the studied low-alloyed steel, and then the austenite and martensite phase transformations were introduced to the model by user subroutines. The cutting flame was created as a time-dependent heat flux to simulate the movement of the flame.
The model was used for various applications, such as different cutting speeds, flame-cutting of steel plates with different thicknesses, pre-heating and post-heating. The results of all these applications are presented, but the main subjects of the study are the temperature history and residual stress results from the cutting speeds of 150 and 300mm/min. The results obtained from these cutting speeds are encouraging and correspond relatively well with the experimental results. Further study is needed to completely verify the model, as the approach to the modelling of the flame is slightly different from earlier studies.
To thoroughly understand and optimize the flame-cutting process for preventing the cracking, more information about the conditions inside the steel plate, while it is being applied with a large amount of heat, is needed. Temperature history is the defining factor to the phase distribution of steel, and creating an optimal microstructure is the desired outcome of every heat-treatment process. By modelling the process, more information about the stress distribution and the temperature history can be obtained.
A model of flame-cutting of low-alloyed steel was made by using a commercial finite element program ABAQUS. First the material was created to resemble the characteristics of the studied low-alloyed steel, and then the austenite and martensite phase transformations were introduced to the model by user subroutines. The cutting flame was created as a time-dependent heat flux to simulate the movement of the flame.
The model was used for various applications, such as different cutting speeds, flame-cutting of steel plates with different thicknesses, pre-heating and post-heating. The results of all these applications are presented, but the main subjects of the study are the temperature history and residual stress results from the cutting speeds of 150 and 300mm/min. The results obtained from these cutting speeds are encouraging and correspond relatively well with the experimental results. Further study is needed to completely verify the model, as the approach to the modelling of the flame is slightly different from earlier studies.