Fatigue Behavior of Friction Spot Stir Welding with No-Keyhole of Aluminum Alloy

2014 ◽  
Vol 1052 ◽  
pp. 509-513 ◽  
Author(s):  
Xi Jing Wang ◽  
Xiao Long Wang ◽  
Zhong Ke Zhang ◽  
Lei Wang ◽  
Qing Shan Zhao ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Spot Welding ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Strengthening Phase ◽  
Friction Stir ◽  
Increasing Trend ◽  
Fracture Appearance ◽  
Welding Joints

The fatigue properties of refill friction stir welding joints of 6082-T6 aluminum alloy were completed based on the optimal process parameters. The expression of the fatigue life prediction were obtained in a certain range. The microstructure and fatigue fracture appearance of welding joints were observed and analyzed. And the microhardness of the joints were tested. The results showed that the fatigue crack initiated from the root of the joints between the lower and upper plate, that is the junction of HAZ and TMAZ, and then propagated to fracture along the boundary between the HAZ and the TMAZ. Strengthening phase which was formed of trace elements significantly affected the fatigue properties of spot welding joints. The fatigue life of spot welding joints along with stress intensity factors decrease showed an increasing trend. Fatigue life of spot welding joints emerge an increasing trend along with decreases of the load.

scholarly journals Fatigue behavior of Al-Al and Al-steel refill friction stir spot welding joints

2021 ◽  
Author(s):  
Haokun Yang ◽  
detao Cai ◽  
Jiaxin Li ◽  
ChinYung Kwok ◽  
yunqiao Zhao ◽  
...  
Keyword(s):  
Spot Welding ◽  
Fatigue Behavior ◽  
Friction Stir Spot Welding ◽  
Friction Stir ◽  
Welding Joints

scholarly journals The Effect of Laser Peening without Coating on the Fatigue of a 6082-T6 Aluminum Alloy with a Curved Notch

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 728 ◽  
Author(s):  
Enrico Troiani ◽  
Nicola Zavatta
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Fatigue Behavior ◽  
Surface Hardness ◽  
Element Model ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Laser Peening ◽  
Laser Peening Without Coating

Laser shock peening has established itself as an effective surface treatment to enhance the fatigue properties of metallic materials. Although a number of works have dealt with the formation of residual stresses, and their consequent effects on the fatigue behavior, the influence of material geometry on the peening process has not been widely addressed. In this paper, Laser Peening without Coating (LPwC) is applied at the surface of a notch in specimens made of a 6082-T6 aluminum alloy. The treated specimens are tested by three-point bending fatigue tests, and their fatigue life is compared to that of untreated samples with an identical geometry. The fatigue life of the treated specimens is found to be 1.7 to 3.3 times longer. Brinell hardness measurements evidence an increase in the surface hardness of about 50%, following the treatment. The material response to peening is modelled by a finite element model, and the compressive residual stresses are computed accordingly. Stresses as high as −210 MPa are present at the notch. The ratio between the notch curvature and the laser spot radius is proposed as a parameter to evaluate the influence of the notch.

Fatigue Life Prediction of Al-Li Alloy Butt-Welded Joints in Aerospace Structures

2009 ◽  
Author(s):  
Muhammad A. Wahab ◽  
Vinay Raghuram
Keyword(s):  
Fatigue Life ◽  
Crack Propagation ◽  
Life Prediction ◽  
Space Shuttle ◽  
Fatigue Behavior ◽  
Fatigue Life Prediction ◽  
Fatigue Properties ◽  
Interface Element ◽  
Aerospace Structures ◽  
Friction Stir

Friction-Stir-Welding (FSW) has been adopted as a major process for welding Aluminum aerospace structures. AA-2195 is one of the new generations Aluminum alloy (Al-Li) that has been used on the new super lightweight external tank of the space shuttle. The Lockheed Martin Space Systems (LMSS), Michaud Operations in New Orleans is continuously pursuing FSW technologies in its efforts to advance fabrication of the external tanks of the space shuttle. The future launch vehicles which will have to be reusable, mandates the structure to have good fatigue properties, which prompts an investigation into the fatigue behavior of the friction-stir-welded aerospace structures. The butt-joint specimens of Al-2195 are fatigue tested according to ASTM-E647. The effect of Stress ratios, Corrosion-Preventive-Compound (CPC), and periodic Overloading on fatigue life is investigated. Scanning Electron Microscopy (SEM) is used to examine the failure surfaces and examine the different modes of crack propagation i.e. tensile, shear, and brittle modes. It is found that fatigue life increases with the increase in stress ratio, the fatigue life increases from 30–38% with the use of CPC, the fatigue life increases 8–12 times with periodic overloading; crack closure phenomenon dominates the fatigue facture. Numerical Analysis using FEA has also been used to model fatigue life prediction scheme for these structures, the interface element technique with critical bonding strength criterion for formation of the new surfaces has been used to model crack propagation. The fatigue life predictions made using this method are within the acceptable ranges of 10–20% of the experimental fatigue life. This method overcomes the limitation of the traditional node-release scheme and closely follows the physics of crack propagation.

scholarly journals Effect of Corrosion and Surface Finishing on Fatigue Behavior of Friction Stir Welded EN AW-5754 Aluminum Alloy Using Various Tool Configurations

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3121 ◽  
Author(s):  
Abootorab Baqerzadeh Chehreh ◽  
Michael Grätzel ◽  
Jean Pierre Bergmann ◽  
Frank Walther
Keyword(s):  
Climate Change ◽  
Aluminum Alloy ◽  
Fatigue Behavior ◽  
Salt Spray ◽  
Base Material ◽  
Fatigue Properties ◽  
Surface Finishing ◽  
Friction Stir ◽  
Stationary Shoulder ◽  
Root Surfaces

In this study, fatigue behavior of surface finished and precorroded friction stir welded (FSW) specimens using various tool configurations were comparatively investigated by the load increase method. The FSW using conventional, stationary shoulder and dual-rotational configurations was carried out by a robotized tool setup on 2 mm EN AW-5754 aluminum sheets in butt joint formation. After extraction of the specimens, their weld seam and root surfaces were milled to two different depths of 200 µm and 400 µm to remove the surface and the FSW tool shoulder effects. This surface finishing process was performed to investigate the effect of the surface defects on the fatigue behavior of the FSW EN AW-5754 aluminum alloy sheets. It was found that material removal from the weld and root surfaces of the specimens, increased the fracture stresses of conventional and dual-rotational FSW from 204 to 229 MPa and 196 to 226 MPa, respectively. However, this increase could not be detected in stationary shoulder FSW. Specimens with finished surfaces, which showed superior properties, were used in salt spray and cyclic climate change test to investigate the effect of corrosion on the fatigue behavior of FSW specimens. It was shown that cyclic climate change test reduced the fatigue properties of the base material, conventional, stationary shoulder and dual-rotational FSW approximately 1%–7%. This decrease in the fatigue properties was greater in the case of the salt spray test, which was 7% to 21%.

scholarly journals Effect of Cavitation Peening on Fatigue Properties in Friction Stir Welded Aluminum Alloy AA5754

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 59
Author(s):  
Hitoshi Soyama ◽  
Michela Simoncini ◽  
Marcello Cabibbo
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Compressive Residual Stress ◽  
Diffraction Method ◽  
Fatigue Properties ◽  
Surface Residual Stress ◽  
Friction Stir ◽  
Sheet Cavitation ◽  
Lightweight Metals

Friction stir welding (FSW) is an attractive solid-state joining technique for lightweight metals; however, fatigue properties of FSWed metals are lower than those of bulk metals. A novel mechanical surface treatment using cavitation impact, i.e., cavitation peening, can improve fatigue life and strength by introducing compressive residual stress into the FSWed part. To demonstrate the enhancement of fatigue properties of FSWed metal sheet by cavitation peening, aluminum alloy AA5754 sheet jointed by FSW was treated by cavitation peening using cavitating jet in air and water and tested by a plane bending fatigue test. The surface residual stress of the FSWed part was also evaluated by an X-ray diffraction method. It was concluded that the fatigue life and strength of FSWed specimen were improved by cavitation peening. Whereas the fatigue life at σa = 150 MPa of FSWed specimen was about 1/20 of the bulk sheet, cavitation peening was able to extend the fatigue life of the non-peened FSW specimen by 3.6 times by introducing compressive residual stress into the FSWed part. This is the first paper to demonstrate the improvement of fatigue properties of FSWed metallic sheet by cavitation peening.

Fatigue Property of Friction Stir Welded Butt Joints for 6156-T6 Aluminum Alloy

2019 ◽  
Vol 960 ◽  
pp. 45-50
Author(s):  
An Chen ◽  
Jun Yang ◽  
Xian Min Chen ◽  
Deng Ke Dong
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Fatigue Behavior ◽  
Fatigue Cracking ◽  
Fatigue Property ◽  
Optical Microscope ◽  
Butt Joint ◽  
Fatigue Properties ◽  
Butt Joints ◽  
Friction Stir

This study was conducted to investigate fatigue behavior of friction stir welding (FSW) butt joints for 6156-T6 aluminum alloy. The detail fatigue rating (DFR) values of 6156-T6 FSW joints is obtained based on statistical analysis of fatigue tests. The micrographs of weld structure were observed by optical microscope (OM), Fatigue fractography was researched under scanning electron microscope (SEM). The results indicate that DFR value of 6156-T6 FSW joints is 153.31MPa. Fatigue property of FSW butt joints is sensitive to the microstructural features, such as nugget zone (NZ), thermo mechanically affected zone (TMAZ) and heat affected zone (HAZ). The hardness distributions of the FSW joints reveal W-shaped profiles. Fractography shows that fatigue cracking is initiated at weak-bonding defects, which are located at the root site of the butt joint. The weak-bonding defects have obvious influence on the fatigue properties of friction stir welding.

Enhanced aluminum alloy-polymer friction stir welding joints by introducing micro-textures

2021 ◽  
pp. 129872
Author(s):  
Wenquan Wang ◽  
Suyu Wang ◽  
Xinge Zhang ◽  
Yuxin Xu ◽  
Yingtao Tian ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Friction Stir ◽  
Polymer Friction ◽  
Welding Joints
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