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All-inclusive Simulation of the Welding
Process in Bell-Mouthed Tubes |
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At present, the development of welding procedures
is basically derived from experimentation, and welding procedure
specifications (WPS) constitute the result of these experimental
procedures. The proper definition and study of such processes
translates as implementations that assure the correct mechanical
behaviour of joints.
The assessment of such procedures is usually carried out on the
basis of the microstructures formed, on the mechanical behaviour
of the joint and on the non-presence of defects. The use of numerical
simulation in the design of welding procedures may constitute
an effective tool that complements experimentation and allows
a better understanding of the phenomena that take place.
This work presents the results and procedures of a thermomechanical
simulation analysis by means of MEF of a multipass welding process
in bell-mouthed tubes with the aim of shedding light on the underlying
causes of the appearance of multiple faults of cold cracking during
the execution of the job.
From the results of the thermal analysis, it is possible to superimpose
cooling curves with the TTT curves of the steel constituting the
base metal. This procedure permits an approximate prediction of
the presence of fragile microstructures in the joint. On the other
hand, thermomechanical simulation of the whole welding cycle not
only results in the prediction of thermal patterns at all points
on the studied model, but further enables the quantitative and
qualitative estimation of levels of residual stresses obtained
subsequent to the process, thus effectively contributing to establishing
the hypotheses underlying said phenomena. |
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