In this reaserch, distributions of temperature and residual stresses during gas tangstan arc welding (GTAW) with heat sink technique (HSW) for Monel 400 alloy plates were simulated. For this reason a 3D thermal-mechanical model was developed by finite element code ANSYS. The Goldak model was applied as the heat source. Kinematic hardening principle and Von Mises ceriteria were used to express flow behavior. To validate the results of the present mixed model, experimental mesearments of temperature were done by thermocouple and residual stresses distribution by hole drilling method. Furthermore, the effects of heat input power density and canal daiameter on the temperature and residual stresses distribution were evaluated. Thermal results showed that decreasing power density of heat input, resulted in increasing width of peaks of the temperature-time curves and decreasing residual stresses. With increasing the canal daiameter of fluid flow from 16.5 to 25.5mm,the maximum decreasing of temperature on top and bottom surface of the sample is 30% and 50% respectively. Increasing canal daiameter is led to maximum decreasing longitudinal residual stresses 130% on the bottom, and 50% on top surface of sample. However, it did not have any influence on the transverse residual stresses. Increasing flow rate of cooling media did not have any effects on bottom surface longitudinal stresses, but it decreases top suface longitudinal stresses. This research showed that HSW is one of the impressive methods to decrease residual stresses. Keywords : GTAW; Heat sink welding, Temperature field, Finite element method, Monel400
