Finite element analysis of the effect of porosity on residual stress in 2024 aluminium alloy GTAW

Abstract

Simulations of the welding process for butt joints using finite element analysis (FEA) of the effect of porosity are presented. The metal used was aluminium alloy (grade 2024), and the filler material was alloy ER5356. The simulations were performed using the commercial software ANSYS, considering a double ellipsoid heat source, temperature-dependent material properties, material deposits, mechanical analysis, transient heat transfer, and defects (porosity). In this study, the FEA simulations were constructed for two types of heat source (singleand double-ellipsoid) used in gas tungsten arc welding (GTAW), and the calculated residual stress results were compared with the experimental values. Two double ellipsoid models were constructed for cases with and without porosity. The porosity was measured by three-dimensional (3D) computed tomography (CT), and the size and location of pores were mapped onto the weld bead created by the birth-and-death technique.

Shielding gas influence on AA5086 welded joints: residual stresses analysis, microstructural characterisation and mechanical properties

“…The formation of pores can be reduced by proper joint preparation, use of high purity shielding gas with lowdew-point and careful storage of the ller metal. However, the 5XXX series ller alloys, as used in this research, are particularly susceptible to surface oxide hydration, which promotes the porosity formation [13,14].…”

Experimental Investigation of Additive Manufacturing Using a Hot-Wire Plasma Welding Process on Titanium Parts

“…Pores serve as stress risers that are brittle fractures and that increase the susceptibility to failure [ 39 ]. Several studies have shown that advanced tools can help detect faults or other defects that occur in the welding process such as ultrasonic non-destructive testing (NDT) techniques [ 30 ], X-ray CT methods [ 35 , 42 ], and radiographic testing (RT) [ 43 , 44 ]. The slow welding speeds and the welding in the flat position, or uphill in the vertical position, encourage the escape of pores [ 45 ].…”

Non-invasive optical characterization and estimation of Zn porosity in gas tungsten arc welding of Fe–Al joints using CR model and OES measurements

“…To cross-validate the present zinc-induced porosity results in Al-Fe weld joints, results are compared with an independent approach based on x-ray computed tomography imaging. This technique allowed us to obtain a non-destructive, three-dimensional (3D) view of the weld and quantify any defects that may have occurred during the welding process [10]. The sample was placed on a rotating turntable between the x-ray source and detector, and x-rays were passed through the sample.…”

“…Porosity defects can weaken the strength and integrity of the weld joint. Therefore it is essential to understand and quantify the porosity defects to optimize the GTAW processes [10].…”

“…These numerical models are computationally expensive and are proposed for porosity due to keyhole in the laser welding but not for the porosities induced by different vapors like Zn vapor. The results of welding simulations are often validated with experimental tests, but these tests can have uncertainties that make it challenging to debug [10]. Overall, the existing nondestructive testing methods or CFD-based models are not suitable for real-time monitoring and fast detection of defects during the welding operation.…”