Experimental Investigation of Fatigue Crack Growth in the Welding Nugget of FSW Joints of a 6060 Aluminum Alloy

2011 ◽  
Vol 488-489 ◽  
pp. 343-346 ◽  
Author(s):  
Paolo Marcassoli ◽  
Michela Longo ◽  
Gianluca D'Urso ◽  
Claudio Giardini ◽  
T. Pastore
Keyword(s):  
Growth Rate ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Base Material ◽  
Speed Ratio ◽  
Feed Speed ◽  
High Feed

The work investigates the fatigue behavior of friction stir welded butt joints by means of fracture mechanics techniques. FSW joints of artificially aged AA6060 T6 aluminum alloy were studied. The welding was performed on 8 mm thick butt joined sheets by means of a CNC machine tool. Welding speed in the range between 117 and 683 mm/min and tool rotational speed between 838 and 1262 rpm were considered. Fatigue crack growth tests were performed according to ASTM E647 standard on CT specimens, under constant load amplitude conditions, at 0.1 minimum to maximum load ratio, with the notch placed in the dynamic recrystallization zone of weld nugget, oriented along the welding direction. The comparison of results demonstrates the crack growth rate is always equal or lower than the base material at low values of stress intensity range. At ΔK values above 12 MPa√m, crack growth rate was found to be higher than base material for high feed, low speed and high feed/speed ratio.

Reliability Analysis of Corrosion Fatigue Crack Growth for 2024-T3 Aluminum Alloy

2008 ◽  
Vol 44-46 ◽  
pp. 105-110
Author(s):  
Sen Ge ◽  
Zhong Li ◽  
J.G. Zhang ◽  
Y.C. Xiao ◽  
G.Q. Liu ◽  
...  
Keyword(s):  
Growth Rate ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Reliability Analysis ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Loading Frequency ◽  
Corrosive Environment

Fatigue crack growth rate experiments of center-cracked tension (CCT) specimens of the 2024-T3 aluminum alloy under constant-amplitude load in corrosive environment are carried out with 3 kinds of loading frequency. The fatigue crack growth rates in 3.5% NaCl solution are obtained by using seven-point incremental polynomial method. A probabilistic approach is presented for fatigue crack growth rate in corrosive environment with log-normal random variable model. The reliability analysis of crack propagation is conducted based on the experimental data. The crack exceedance probability at given service time and the distribution of the service time at given crack size are obtained by using the reliability analysis approach. The effect of loading frequency on crack propagation is studied. It is shown that the fatigue crack growth rate is increasing with loading frequency decreasing in corrosive environment. The predicted results by the presented method match the experimental results very well.

scholarly journals Fatigue crack growth in aluminum alloy from cold expanded hole with preexisting crack

2020 ◽  
Vol 99 (3) ◽  
pp. 5-16
Author(s):  
P. Yasniy ◽  
O. Dyvdyk ◽  
O. Semenets ◽  
V. Yasnii ◽  
A. Antonov
Keyword(s):  
Growth Rate ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Residual Lifetime ◽  
Aircraft Structure ◽  
Edge Notch

The fatigue life of aircraft structure elements with operational damage in the vicinity of the hole was investigated. The plates 60 mm wide and 6 mm thick made of D16chT aluminum alloy with a central hole were taken for the study. Fatigue damage was examined with an corner quarter-elliptical fatigue crack with a length of 1,25 mm, which was initiated from an edge notch of 0,5 x 0,5 mm. The fatigue crack growth rate on the surface of the plate after mandrel hole with cold expansion degree i = 2,7% increases up to15 times and residual lifetime in three times compared to the virgin plate.

Fatigue Crack Growth on FSW AA2024-T3 Aluminum Joints

2012 ◽  
Vol 498 ◽  
pp. 126-138 ◽  
Author(s):  
Pedro Miguel Guimarães Pires Moreira ◽  
Paulo Manuel Salgado Tavares de Castro
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Solid State ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Base Material ◽  
Welding Process ◽  
Butt Joints ◽  
Friction Stir

Friction stir welding (FSW) is a solid-state joining process which emerged as an alternative technology to join high strength alloys that were difficult to weld with conventional techniques, [1]. Developments of this technique are being driven by aeronautic, aerospace and railway industries. An advantage of this joining technique is its low heat input when compared with arc welding processes. This feature allows the achievement of high mechanical properties, low distortion and low residual stresses, [2]. Also, since it is a solid-state welding process, hydrogen cracking or heat affected zone (HAZ) softening phenomena are limited. This paper presents a study of fatigue crack growth behaviour of friction stir welded butt joints of AA2024-T3, aluminium commonly used in riveted aeronautic fuselage structures. Crack growth studies are often carried out using uniform thickness joints, ASTM E647 [3]. Nevertheless, for some applications there is a need to join components with different thicknesses, which, under certain limits, can be welded using FSW. Crack growth tests on these joints are not standard. The present study concerns butt joints made using two plates with different thicknesses, 3.8mm and 4.0mm. The joints’ mechanical behaviour was studied performing static (tensile) and fatigue tests. The fatigue crack growth rate of cracks growing in different zones of the welded joint (nugget, heat affected zone - HAZ) and in base material was analysed. The microhardness profile was assessed in order to analyse the influence of the welding process in each weld zone. Further to higher static properties, welded joints present lower crack growth rate when compared with its base material.

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