Procedure to predict residual stress pattern in spray transfer multipass welding

Abstract

Gas metal arc welding (GMAW) is one of the most used joining method in the industry.However, one of the main problems of this process is the generation of residual stresses which have direct impact on the fatigue life of welded components. Nevertheless, residual stress pattern prediction is complex and requires the simulation of the welding process. Currently, there are different numerical methods to predict the residual stresses generated in GMAW process, being Goldak's method one of the most widely used model. However, the main limitation of these methods is that they require defining many parameters experimentally and consequently this method is not valid during design process.Alternatively, in this work, it is developed a procedure where the heat source is defined based on the welding physics for spray transfer welding. The developed procedure has been validated for a spray transfer multipass butt weld case. Results have shown good correspondence with an average deviation of 9.16% in thermal field and 42 MPa in the final residual stress field. Thus, the developed procedure has been validated as a cost effective alternative method to estimate residual stress pattern in spray transfer multipass welding. Furthermore, the developed method does not require any welding experimental characterization once the efficiency of the used welding machine is defined. The proposed method can be used as a valid tool to optimize the welding process in order to minimize the residual stress field and, consequently, improve the fatigue life.

Fatigue analysis of multipass welded joints considering residual stresses

“…Then, process parameters are defined based on the heat source analytic model implemented as input data to feed the FEM model. In this work, 10 mm thick S275JR plates and 1.2 mm diameter PRAXAIR M-86 filler wire according to the AWS/ASME SFA 5.18 ER70S-6 standard are used, as in [38]. Table 2 shows the defined process parameters for each pass of the welding process of the three samples as well as the input parameters for the FEM model.…”

“…The RS pattern of the three welded samples are obtained from the uncoupled thermomechanical FEM simulation following the procedure presented by Lopez-Jauregi et al [38]. In this procedure, heat source is defined based on the welding physics for spray transfer welding in accordance with the cross section of each pass.…”

“…First, RS pattern of the welded samples is estimated based on the numerical procedure presented recently by the authors [38]. Then, life estimation for HCF is conducted by considering the influence of the RS in the critical zone.…”

“…A CNC milling machine (GSP machine tool with Fagor 8025 CNC) and a welding machine Praxair Phoenix 421 have been adapted to perform the welding process automatically controlling all process parameters such as welding speed, arc length, contact to workpiece length, voltage and wire feed speed [38].…”

“…This paper is aimed at developing a procedure to estimate accurately the HCF life of different geometries of multipass spray transfer welded joints considering initial RS. For that purpose, initial RS are calculated following the recently developed modelling procedure to predict RS pattern in multipass welding [38]. Three geometries of welded joints have been analysed in detail: (i) 0°butt weld, (ii) 45°butt weld and (iii) T-joint welding.…”