Issue 48

M. Tirenifi et alii, Frattura ed Integrità Strutturale, 48 (2019) 357-369; DOI: 10.3221/IGF-ESIS.48.34 359 measurement of transverse residual stress can be observed in some locations. The manufacturing residual stress possibly influenced the experimental results at some points. When the distance to the weld line increases, the welding effect on the final residual stress is small. The manufacturing stress will then have more influence on final stress field. Weld joint configuration actually refers to more than just the joint geometry. Besides the shape or configuration of individual weld joints, it includes the location or placement of joints within the structure, that is, the structural arrangement. Together, joint configuration and the number and placement of weld joints determines ease of manufacture, cost, and structural integrity, including robustness against weld-induced distortion. The purpose of this article is to study the temperature distribution and the residual stresses generated during welding by a numerical simulation for two different types of chamfers X-Groove and V-Groove. Moreover, this article was enriched by a numerical study to identify the K and G parameters for different crack lengths. Finally, we finish our work with a numerical study to describe the fracture behavior of the material for the three zones of the weld. The material chosen for this study is low carbon steel SA-516 Gr 70, which is the material commonly used for the manufacture of pressure vessels. The aim of this contribution is to investigate the influence of various welding sequence schemes on distributions and values of residual stresses and distortions of SA 516 Gr 70 steel. The cruciform joint and butt-joint plates are investigated using a transient thermo mechanical analysis performed by the finite element program, ABAQUS. Moreover, in this present study compares the stress intensity factor of cruciform and the butt welded joint, in order to determine the influence of the joint geometry on the fracture mechanics parameters. D ESCRIPTION OF THE NUMERICAL MODEL Material proprieties n this study we have choose two specimens welded by deferent types; cruciform welded joint and butt welded joint. The material of the plates is no allowed steel SA 516 Gr.70, with temperature-dependent thermal and mechanical material properties adopted from [22]. Fig. 1 present the mechanical behavior of steel SA 516 Gr.70 as a function of the temperature. The material model (PLASTIC_KINEMATIC) has been introduced with the mechanical properties coming from ASME, Section-II, Materials Properties, Part-D. Element (%) C S P Si Mn Ni Cr Mo Cu Ti V SA 516 Gr.70 0.16 0.005 0.013 0.44 1.45 0.08 0.07 0.008 0.038 0.004 0.1 Table 1 : Chemical compositions. Material Mechanical properties Thermal Properties Yield Strength (MPa) Tensile Strength (MPa) Elongation at Break (%) Modulus of Elasticity (GPa) Poisson’s Ratio Bulk Modulus (GPa) Shear Modulus (GPa) Specific Heat Capacity (J/g-°C) Thermal Conductivity (W/m-K) SA 516 Gr.70 355 485-620 21 220 0.3 160 80 0.44 36.3 Table 2 : Mechanical properties and thermal properties at room temperature [23]. N UMERICAL MODELING OF THE WELDING SIMULATION n the form of an Abaqus/CAE Plug-In, that provides an easy-to-use graphical user interface to setup cross sectional (2-dimensional and axisymmetric) welding simulations from within Abaqus/CAE. The 2-D assumption where only a (planar or axisymmetric) 2-D cross section of the welded geometry is modeled is appropriate when the heat flow in the welding direction is minimal (such as when the welding speed is high). The AWI is setup assuming the following methodology for performing a 2D welding simulation [24]: 1.The weld torch is simulated by applying a prescribed temperature (of magnitude higher than the melting temperature) at the boundary between the beads involved in the current weld pass and the neighboring region. I I