Numerical Modelling of Thermal and Structural Strain in Laser Welding Process / Modelowanie Numeryczne Odkształceń Cieplnych I Strukturalnych W Procesie Spawania Techniką Laserową

Abstract

This work concerns numerical modelling of thermal and structural strain, resulting in heating and cooling of laser butt-welded joints. Numerical analysis of strain is carried out in Abaqus FEA. Through the use of additional author's subroutines, the structural strain caused by phase transformations during heating and cooling of welded elements is taken into account in the analysis. V.I. Machnienko models as well as Continuous Heating Transformation (CHT) and Continuous Cooling Transformation (CCT) diagrams for S355 steel are implemented into UEXPAN subroutine in order to determine the kinetics of phase transformation in the solid state. The model takes into account thermomechanical properties of the base material varying with temperature.The paper presents results of numerical simulation of temperature field, predicted structural composition, thermal and structural strain in laser butt-welded joints.Keywords: Laser welding, heat transfer, phase transformations, numerical modelling, isotropic strain W pracy przedstawiono numeryczne modelowanie odkształceń cieplnych i strukturalnych, powstających podczas nagrzewania i chłodzenia, złącza spawanego doczołowo wiązką promieniowania laserowego. Analizę numeryczną odkształceń przeprowadzono w programie Abaqus FEA. Dzięki zastosowaniu dodatkowych autorskich aplikacji w analizie uwzględniono odkształcenia strukturalne wywoływane przemianami fazowymi podczas nagrzewania i chłodzenia spawanych elementów. Do wyznaczenia kinetyki przemian fazowych w stanie stałym zastosowano modele V.I. Machnienki oraz wykresy CTP A i CTPc-S dla stali S355 implementowane do procedury UEXPAN. W modelu uwzględniono zmienne z temperaturą własności termomechaniczne spawanego materiału.Przedstawiono wyniki symulacji numerycznych pola temperatury, prognozowanego numerycznie składu strukturalnego oraz odkształceń termicznych i strukturalnych w złączu spawanym doczołowo wiązką promienia laserowego.

Numerical Modelling Of Thermal And Structural Phenomena In Yb:YAG Laser Butt-Welded Steel Elements

“…Many issues concerning this type of laser materials processing are currently under particular investigations in the field of mathematical and numerical modelling as well as experimental research [3][4][5][6][7][8][9].…”

“…The beam is afterwards transferred to the walls of the "keyhole" forming the fusion zone [12][13][14]. Moreover, the impact of concentrated heat source on the material causes high temperature gradients as well as different heating and cooling conditions, contributing to the formation of various structures in the weld and heat affected zone, which leads to different mechanical properties [6,10]. Hardening structures occur in the thermal influence zone due to the impact heating and rapid cooling of a material in the process, even in susceptible to the laser processing, unalloyed and low-alloy constructional steels.…”

The Influence Of Burner Locations In The Heating Furnace On The Charge Temperature Field

“…In order to ensure the correct operation of the technological system, it is necessary to achieve the required temperature in the whole volume of the charge and ensure its uniformity. Modelling of the temperature field and other phenomena as regards the process of steel production has been analysed by several authors, with both commercial software and original formulations having been applied [1][2][3][4][5][6][7][8].…”

The Development Of Heating Curves For Open Die Forging Of Heavy Parts

“…The problem of calculating strains and stresses occurring in materials during the manufacturing processes is vital [3,4]. In order to avoid defects caused by fractures, indicators that define acceptable thresholds of strains and stresses that do not cause the occurrence of fractures are determined.…”