Effect of Porosity on the Fatigue Behavior of Gas Metal Arc Welding Lap Fillet Joint in GA 590 MPa Steel Sheets

Abstract

Weld defects such as blowholes and surface pores occur due to zinc vaporization during the gas metal arc welding of lap fillet joints of Zn-coated steel. In this study, the effect of porosity on fatigue behavior was investigated. A Zn-coated steel sheet with the strength of 590 MPa and a thickness of 2.3 mm was used as the base material. Three kinds of specimens with weld pore defects, such as blowholes and surface pores, were prepared and the tensile shear strength, hardness and fatigue behavior were investigated. The pore defects in the welds reduced the tensile shear strength. In the fatigue test, at higher load stresses between 122 and 366 MPa, pore defects reduced the fatigue life of the weld. However, the pore defects in the welds did not significantly affect the fatigue life of the welds at stresses below 92 MPa.

Influence of Local Properties on Fatigue Crack Growth of Laser Butt Welds in Thin Plates of High-Strength Low-Alloy Steel

“…In the last specimens of the S5 series shown in Figure 9k-l, it is relevant that once the imperfections on both sides of the weld beads were removed, the fatigue failure corresponded to pores; surface pores located on the lateral side for the specimen with shorter In the last specimens of the S5 series shown in Figure 9k,l, it is relevant that once the imperfections on both sides of the weld beads were removed, the fatigue failure corresponded to pores; surface pores located on the lateral side for the specimen with shorter life (56,343 cycles) and internal pores for the specimen with longer life (207,400 cycles). The apparent scatter previously mentioned for these specimens is actually the effect of the location of the pores in the specimens, as reported in the literature for pores near the surface and for internal pores [37,38]. From the previous review on fractured surfaces, for the stress level examined, it can be inferred that in the fatigue life the type and shape of the imperfections are less important than the size, quantity and location, and there was a certain order in the fatigue lives of the specimens, from the lowest to the highest: a continuous very small surface imperfection along of the width of specimen; various surface imperfections covering the width of the specimens or imperfections near to the border that produce fatigue in the lateral side, but growing semi-elliptically; surface pores or pores near to the surface in the lateral side; one big or a few small surface imperfections that do not cover the width of the specimen, that growth as one semi-elliptical crack; a condition similar to the previous one but with very small imperfections and one or various internal imperfections (pores).…”

Welding of AA6061-T6 Sheets Using High-Strength 4xxx Fillers: Effect of Mg on Mechanical and Fatigue Properties

“…The porosity levels of the joints with the newly developed fillers were higher than that of the joint with the commercial ER4043 filler. However, the porosity level (0.3 vol.% ± 0.03 as the area fraction of pores in the weld area of the whole weld seam) was still within an acceptable range (quality level B: <1%) according to the ISO 10042:2005(E) standard [ 26 ]. Although X-ray radiography is useful for revealing macroscopic defects, it is not suitable for examining microscopic defects (sizes of <100 µm) due to its low spatial resolution and signal-to-noise sensitivity [ 27 ].…”

Improving Fatigue Performance of Laser-Welded 2024-T3 Aluminum Alloy Using Dry Laser Peening

“…Therefore, the effect of positive factors induced by DryLP, such as hardening and compressive residual stress, was larger than that of the negative factors, such as stress concentration at undercuts and blowholes at lower stress amplitudes. In addition, for gas metal arc welding lap fillet joint in GA 590 MPa steel sheets, the blowholes in the WM did not significantly affect the fatigue life at relatively lower stress amplitudes, although the fatigue life decreased in the presence of blowholes and surface pores [40]. Overall, DryLP effectively improved the fatigue performance of laser-welded specimens containing welding defects at lower stress amplitudes.…”