Prediction of angular distortion in austenitic stainless steel welds using finite element analysis

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The present work was carried out with an aim of predicting angular distortion in AISI 304 welds fabricated using Shielded metal arc welding (SMAW) process. Since distortion results into loss of structural integrity which consequentially affects service performance of welded structures adversely, so studies on its prediction carry industrial significance to devise their preventing as well as controlling strategies. Experimental welds involved welding of 16.4 mm thick AISI 304 austenitic stainless steel plates using SMAW process using three different levels of welding heat input. Angular distortion was measured for each welded joint. Thereafter numerical analysis of the welds was done using Finite Element Method. This model was rather a simpler one as it did not consider temperature dependent properties of materials. A moving heat source was implemented to simulate the welding process which was modelled using Gaussian heat flux source. Owing to the simplicity of the model, filler material addition and multi-pass weld deposition were not considered. The whole analysis regime was divided into two steps, first a non-linear transient thermal analysis was performed to predict the temperature, and subsequently the predicted thermal load was then used as an input to perform non-linear transient structural analysis using ANSYS Workbench. To prevent the integrity of the plate in FE model, frictionless support was added as a boundary condition. For simulating the welding environment, the environment in simulation was chosen to be stagnant air and convective heat transfer loss was also considered. The numerical simulation data was then compared with the experimentally measured data. The results of this study reveal that the FE model was able to predict the angular distortion in welds to a reasonable extent, the fidelity of which can be further increased if temperature dependent property, filler metal addition and multilayer weld deposition are also taken in account.