Papers by Keyword: Welding Simulation

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Authors: Fábio Renck Locatelli, Walter Jesus Paucar Casas, Ricardo Frederico Leuck Filho
Abstract: The welding involves the transfer of high localized heat flow, which results in residual stresses in the welded body. The impossibility of relieving these stresses generates welding distortions that become a problem in dimensional setting of welded structures. This study aims to evaluate the influence of some parameters in the welding process in a T-type joint. Due to the complexity of the welded joint and the deposition rate, a three-dimensional finite element model was developed for the solution of the temperature field and distortions. The transient thermal analysis used the Goldak equation for definition of the heat flux transferred to the part. The nonlinear characteristics of the phenomenon as well as the dependence of physical and mechanical properties with the temperature were considered in this work. The parameters studied were the welding speed, welding sequence and cooling time between weld beads. The results suggest that the higher welding speed, the welding sequence forward and back and with cooling interval between beads present themselves as the best parameters for welding with lower distortions.
Authors: Sveto Cvetkovski
Abstract: The heat input during conventional arc welding processes can be readily calculated knowing the power taken from the power source. The efficiency coefficient can be taken from the appropriate literature standards. Here, the intention of the performed research work was to develop a procedure for determination of heat input in arc and laser welding processes implementing Adams equation - modified Rykalin equation for two dimensional heat distributions (2-D). To realize this idea, it is necessary to determine two characteristic temperatures points in the HAZ with known peak temperature, and to determine distance between them. Implementing measured values for distance in Adams’ equation, heat input in arc welding can be directly determined in arc welded joints.In laser beam welding, the absorption of the beam in the metal is not known, so that the welding heat input cannot be calculated directly, and direct implementation of Adam’s equation is not possible i.e. absorption coefficient has to be determined first, and after that calculation of heat input is possible.The peak temperatures corresponding to specific microstructures can be obtained by performing welding simulation, by the Gleeble 1500 simulator in our case. As one of the peak temperatures, the melting temperature can be used corresponding to the fusion line, so that at least one characteristic peak temperature such as coarse grain zone, fine grin zone, intercritical zone, recrystallization, has to be determined by the simulation.Performed research showed that obtained values for heat input using Adam’s equation correspond pretty well with standard equation for heat input in arc welding.
Authors: Mohd Ridhwan Mohammed Redza, Yupiter H.P. Manurung, Robert Ngendang Ak. Lidam, Mohd Shahar Sulaiman, Mohammad Ridzwan Abdul Rahim, Sunhaji Kiyai Abas, Ghalib Tham, Chan Yin Chau
Abstract: This paper investigates the simulation technique for analyzing the distortion behavior induced by welding process on welded plate which was clamped on one side. This clamping method is intended to enable the investigation of the maximum distortion on the other side. FEA software SYSWELD was employed to predict multipassed butt weld distortion of low carbon steel with thicknesses of 6 mm and 9 mm. The simulation begins with the development of model geometry and meshing type followed by suitable selection of heat source model represented by the Goldak’s double ellipsoid model. Other parameters such as travel speed, heat input, clamping method etc. were determined. The model is dedicated for multipass welding techniques using Gas Metal Arc Welding (GMAW). The experimental works were conducted by using Robotic welding process.
Authors: Kun Han, Qing Shan Li, Mei Zhang, Ren Yu Fu, Lin Li
Abstract: Different physical simulation welding parameters were performed using Gleeble-3500 type thermal simulator to research the effect of thermal cycle on microstructure transition and property variation of boron steel 22MnB5. The peak temperature of welding thermal cycle was set to 1320-870°C, and cooling rates t8/5 to 6s-100s. Then microstructure observation, hardness detection, and impact toughness tests were carried out to clarify the effect of different thermal cycles. The results show that 22MnB5 has good mechanical properties, but the toughness decreases obviously under certain thermal cycles, showing cold crack sensitivity of 22MnB5. Martensite and ferrite are the main microstructure under different peak temperature and t8/5.
Authors: Rui Wang, Dong Feng Li, Xin Li Han, Jianxun Zhang
Abstract: In this paper, the convex distortion and transient distortion characteristics of TIG welding for a titanium alloy with finite dimensional thin plate were investigated experimentally and numerically. A three dimensional thermal-mechanical finite element method (FEM) was adopted to predict the characteristics of Transient distortion by taking the initial shape, gravity loading and restriction conditions into account. The simulation results were validated by the experimental results. The results show that the numerical simulations could provide accurate prediction on the Transient temperature and distortion processing. The temperature gradient through thickness, the dimension of plate and the clamping were main factors governing the distortion during welding.
Authors: T. Schenk, I.M. Richardson, G. Eßer, M. Kraska
Abstract: The accurate prediction of welding distortion is an important requirement for the industry in order to allow the definition of robust process parameters without the need to perform expensive experiments. Many models have been developed in the past decades in order to improve prediction. Assumptions are made to make the models tractable; however, the consequences are rarely discussed. One example for such an assumption is the strain hardening model, which is often a choice between either kinematic or isotropic hardening. This paper presents the results of tensile tests for DP600 performed from room temperature up to one thousand degrees and for different strain-rates. In order to employ a mixed isotropic-kinematic hardening model, the fractions of each hardening contribution have been determined by means of bend testing. The welding distortion of a DP600 overlap joint has been simulated and it is shown that such a mixed-hardening model results in more accurate and reliable results.
Authors: Sadegh Moeinifar
Abstract: The objective of this paper is to study the influence of second peak temperature during simulated welding on properties of the subcritically (S), intercritically (IC) and supercritically (SC) reheated coarse grained heat affected (CGHAZ) zones. This involved heating to a first peak temperature (TP1) of 1400 °C, then reheating to different second peak temperatures (TP2) of 700, 800 and 900 °C with a constant cooling rate of 3.75 °C/s. Toughness of the simulated reheated CGHAZ regions were assessed using Charpy impact testing at 0 and -50 °C. The blocky and connected M/A particles, along prior-austenite grain boundaries, act as a brittle phase for the initiation site of the brittle fracture. Charpy impact results indicated that IC CGHAZ had less absorbed energy with higher transition temperature and hardness.
Authors: M.P. Shalimov, E.B. Votinova
Abstract: The way of calculation of welding electrode coating composition using the results of experimental and theoretical investigation into the processes of interaction in a metal-slag-gas system under the conditions of manual arc welding is described.
Authors: Fabien Corpace, A. Monnier, A. Poulon Quintin, J P. Manaud
Abstract: ODS steels (Oxide Dispersion Strengthened) are candidate materials for fuel cladding in Sodium Fast Reactors (SFR). These materials have good mechanical properties at high temperature due to a dispersion of nanometer-sized oxides into the matrix. Previous studies have shown that melting can induce a decrease of the mechanical properties at high temperatures due to modifications of the nanometer-sized oxide dispersion. Therefore the fusion welding techniques are not recommended and the solid state boundings has to be evaluated. This study is focused on resistance upset welding. Welding experiments and numerical simulations are coupled. The numerical simulation is developed in order to have a better understanding of the thermal and the mechanical phenomena occurring during the welding process. The simulation shows that the welding steps can be divided in two stages. First, the temperature of the contact between pieces increases. Second, the heat generation is mainly located in the cladding leading to the collapse and forging the pieces. The microstructural observations confirm that the major deformation is located in the cladding. Oxide dispersion modification and dynamical recrystallisation has been found for welds achieved with a non optimized process parameter set. The deformation and the temperature seem to be of prime importance in the modification of the oxide dispersion.
Authors: Gancho Genchev, Ossama Dreibati, Ralf Ossenbrink, Nikolay Doynov, Vesselin Michailov
Abstract: The paper presents a numerical and experimental approach for the quantification of the thermo-mechanical properties in multi-pass welds heat affected zone (HAZ) of low alloy steel S355J2+N. First, the characteristic temperature cycles for multi-pass welds were identified by FE temperature field simulations of welding. Based on the identified temperature cycles, the microstructure in the HAZ has been physically simulated with the simulation and testing system Gleeble 3500 to investigate the influence of multi thermal exposure on the thermo-mechanical properties. Thus, the thermo-mechanical material properties including thermal strain and temperature dependent stress strain behaviour as function of peak temperatures and cooling rates have been determined. These material properties were used to calibrate a developed model for numerical prediction of the material properties of multi-pass weld HAZ.
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