Effect of Root Flaw on Tensile Behavior of Friction Stir Welded A6061-T6 Aluminum Alloy

2012 ◽  
Vol 482-484 ◽  
pp. 1343-1349
Author(s):  
Ben Yuan Lin ◽  
Ju Jen Liu ◽  
Lee Der Lu ◽  
Hsien Lung J Tsai
Keyword(s):  
Early Stage ◽  
Testing Machine ◽  
Ccd Camera ◽  
Local Strain ◽  
Tensile Tests ◽  
Tensile Behavior ◽  
Tensile Fracture ◽  
Tensile Fracture Surface ◽  
Friction Stir ◽  
Tensile Experiment

The tensile behavior of friction stir joints containing root flaw in A6061-T6 aluminum alloys was investigated. First, plates of this material were butt-jointed by friction stir welding, and the metallographic observation and micro-hardness analysis were made on the cross-section of the weld. Then, tensile tests were performed in MTS 810 testing machine, and a digital CCD camera was used to monitor the process during testing.. Finally, the tensile fracture surface analysis was examined by scanning electron microscopy (SEM). The results show that the root flaw has no apparent effect on the tensile properties. However, it was observed that a crack about 0.3 mm in length occurred in the root part of the weld center in the early stage of tensile test, and the crack did not further propagate during the sequent tensile experiment. The tensile specimens were all fractured in the heat-affected zone (HAZ) of the retreating side, which is the area coincident with the region of maximum local strain and lowest hardness.

Fatigue Properties of Al-Li Plates Joined by Friction Stir Welding

2008 ◽  
Vol 385-387 ◽  
pp. 849-852 ◽  
Author(s):  
Pasquale Cavaliere ◽  
Francesco W. Panella ◽  
Antonio Squillace
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Testing Machine ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Control Mode ◽  
Fatigue Properties ◽  
Amplitude Control ◽  
Friction Stir

Al-Li alloys are characterized by a strong anisotropy in mechanical properties and microstructure with respect to the rolling direction. Plates of 2198 Al-Li alloy were friction stir welded by employing maximum rotation speed: 1000 rev/min and welding speed of 80 mm/min, both in parallel and orthogonal directions with respect to the rolling one. The joints mechanical properties were evaluated by means of tensile tests at room temperature. In addition, fatigue tests performed with a resonant electro-mechanical testing machine under constant amplitude control up to 250 Hz loading, were conducted in axial control mode with R(σmin/σmax)=0.33, for all the welding and rotating speed conditions. The fatigue crack propagation experiments were performed by employing single edge notched specimens.With the aim to characterize the weld performances, both the microstructure evolution at jointed cross sections, related to the welding variables, and the fractured surfaces were respectively analyzed by means of optical and scanning electron microscopy.

Tensile and Creep Properties of the Refractory Nb Base In-Situ Composite

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1608-1614
Author(s):  
Jin Hak Kim ◽  
Tatsuo Tabaru ◽  
Hisatoshi Hirai
Keyword(s):  
Fracture Surface ◽  
Tensile Tests ◽  
Constant Load ◽  
Tensile Creep ◽  
Tensile Fracture ◽  
Creep Tests ◽  
Tensile Fracture Surface ◽  
In Situ Composite ◽  
Temperature Ranges

Niobium-base in-situ composite Nb-18Si-5Mo-5Hf-2C (in mol%) was prepared and heat-treated at 2070 K for 20 hour. The uni-axile tensile tests at high temperature ranges and the constant load tensile creep tests at 1570 K were performed. The specimen tensile-tested at 1470 K exhibited the excellent UTS of 450 MPa, and the brittle to ductile transition temperature is between 1470 and 1670 K. The specimens creep tested showed good creep strength; the stress exponent is about 5. The tensile fracture surface of the in-situ composite is complex and attributed to cleavage of the Nb 5 Si 3, Nb ss / Nb 5 Si 3 interface separation, ductile rupture of the Nb ss and correlations of these. On the otherhand, the fracture surface of creep tested consists of intergranular above 150 MPa and transgranular below 120 MPa with severely deformed Nb ss .

The Influence of Welding Parameters on Tensile Behavior of Friction Stir Welded Al 2024-T4 Joints

2009 ◽  
Vol 83-86 ◽  
pp. 1197-1204
Author(s):  
E. Mahmudi ◽  
Hassan Farhangi
Keyword(s):  
Rotation Speed ◽  
Tensile Behavior ◽  
Tensile Fracture ◽  
Welding Parameters ◽  
Speed Ratio ◽  
Rotating Speed ◽  
Friction Stir ◽  
Fracture Location ◽  
Band Spacing ◽  
Al 2024

In the present study, the relationships between friction stir welding parameters and the tensile behavior of Al 2024-T4 joints was investigated. The aluminum alloy plates were butt-welded using a hardened steel tool with a threaded and fluted cylindrical pin at various tool rotation speed to advancing speed ratios. Metallographic observations, EDS analysis and microhardness measurements show that the band spacing in the periodic microstructure of the stir zone and the average microhardness of this region decrease with increasing speed ratio. Tensile ductility is strongly affected by welding parameters and final elongation increases significantly with speed ratio at the constant rotating speed of 900 rpm. This behavior is found to be associated with a change in tensile fracture location. Formation of microscopic voids at low speed ratios leads to premature fracture in the nugget zone, while in the defect-free joints produced at higher speed ratios the fracture location shifts into the HAZ on the retreating side, which exhibits the lowest microhardness value within the weld joint. At the optimum rotation speed of 900 rpm and speed ratio of 11.2 rev/mm the tensile strength and final elongation of the joints are equivalent to 97% and 77% that of base metal, respectively.

Influence of Early-Stage Hydrolysis on Tensile Fracture Behavior of HAp/PLA Composites Interface-Controlled by Reaction Control Utilizing Photodissociable Protecting Groups

2017 ◽  
Vol 11 (6) ◽  
pp. 932-940 ◽  
Author(s):  
Mototsugu Tanaka ◽  
Tomoyuki Takahashi ◽  
Isao Kimpara ◽  
◽  
◽  
...  
Keyword(s):  
Fracture Behavior ◽  
Control Method ◽  
Early Stage ◽  
Tensile Tests ◽  
Immersion Test ◽  
Interfacial Bonding ◽  
Tensile Fracture ◽  
Interface Control ◽  
Nitrobenzyl Alcohol ◽  
Biological Environment

In this study, the change in the tensile fracture behavior of HAp/PLA composites, interface-controlled using pectin and chitosan, was evaluated for the case of the early-stage hydrolysis. Here, the reaction between the HAp particles and modification polymers was controlled using o-nitrobenzyl alcohol. Tensile tests after immersion in a pseudo biological environment indicated that the interface-control method employed in this study improved the fracture properties of HAp/PLA composites significantly, inducing the large plastic deformation. In addition, the effects of early-stage hydrolysis on fracture behavior and mechanism are discussed from the viewpoint of interfacial structures for the interface-controlled HAp/PLA composites. Observations of fracture morphologies and surfaces suggest that the interface-control employed in this study successfully improved interfacial bonding, enabling the effective usage of the deformability of the PLA matrix. The interface-control method employed in this study also maximized the fracture strain through the combination of improved interfacial bonding and an increase in the ductility of the PLA matrix after a 2-week immersion. Test results also suggest that the cancelation induced by the degradation of chitosan accelerated the degradation of the PLA matrix after a longer immersion.

scholarly journals Effect of Fatigue Life of Dissimilar Aluminium Alloy (AA 5083 - AA 6062) Joining by Friction Stir Welding

2019 ◽  
pp. 314-319
Author(s):  
Sunit Yadav ◽  
Kamal Kanaujia ◽  
Ravi Shukla ◽  
Reetesh Shukla
Keyword(s):  
Friction Stir Welding ◽  
Testing Machine ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Processing Parameters ◽  
Sine Wave ◽  
Fatigue Tests ◽  
Control Mode ◽  
Amplitude Control ◽  
Friction Stir

The effect of processing parameters on the mechanical and microstructural properties of dissimilarAA5083–AA6062 joints produced by friction stir welding was analysed in this study. Different samples were produced by varying the advancing speeds of the tool as 5 mm/min and by varying the alloy positioned on the advancing side of the tool. In all the experiments the rotating speed is fixed at1200 RPM. All the welds were produced perpendicularly to the rolling direction for both the alloys. Microhardness (HV) and tensile tests performed at room temperature were used to evaluate the mechanical properties of the joints. For the mechanical fatigue tests, a resonant electromechanical testing machine was employed under constant loading control up to 10 Hz sine wave loading. The fatigue tests were conducted in the axial total stress–amplitude control mode, with R = rmin/rmax = -1. In order to analyse the microstructural evolution of the material, the welds’ cross-sections a SEM observation was made of the fracture surfaces.

Effects of Different Microalloying and Controlled Cooling Technology on Microstructure and Properties of 500MPa High-Strength Rebars

2014 ◽  
Vol 633-634 ◽  
pp. 168-175
Author(s):  
Wei Chen ◽  
Jian Chun Cao ◽  
Zhe Shi ◽  
Yin Hui Yang ◽  
Yu Zhao
Keyword(s):  
Testing Machine ◽  
High Strength ◽  
Good Effect ◽  
Tensile Fracture ◽  
Controlled Cooling ◽  
Tensile Testing Machine ◽  
Impact Machine ◽  
Obvious Effect ◽  
Tensile Fracture Surface ◽  
Cooling Technology

The mechanical properties and microstructures of three different VN, Nb, V-Nb microalloyed rebars were investigated by using tensile testing machine, impact machine, metallographic microscopy, scaning electron microcopy, transmission electron microscopy and X-ray diffraction apparatus. The results showed that the microstructure of V-Nb microalloyed specimen is consisted of ferrite, pearlite and a small amount of fine bainite (6.7wt%), and obvious effect of grain refinement was obtained with more than 10 size grade of ferrite grain, showing optimal comprehensive properties. SEM micrograph of tensile fracture surface for V-Nb microalloyed 500MPa high-strength rebar is dimple and ductile, ductile-brittle transformation temperature is lower than-30°C, which has good plasticity-toughness and impact toughness at low temperature. The results of precipitates have shown that a large number of small and dispersive V(CN) and Nb (CN) precipitates with size of 5~30nm are formed, good effect of precipitation strengthening was achieved in 500MPa high-strength rebars produced by different microalloying and controlled cooling technology.

scholarly journals Investigation on Evolution of Microstructures and Characterization During FSW of Az80a Mg Alloy

2017 ◽  
Vol 62 (3) ◽  
pp. 1779-1785 ◽  
Author(s):  
P. Sevvel ◽  
V. Jaiganesh
Keyword(s):  
Tensile Tests ◽  
Mg Alloy ◽  
Tensile Fracture ◽  
Tool Rotational Speed ◽  
Nugget Zone ◽  
Sem Images ◽  
Friction Stir ◽  
Az80a Mg Alloy ◽  
Tool Pin ◽  
Scanning Electron

Abstract Experimental investigation was conducted to find out microstructural characteristic changes arising in the weldments AZ80A Mg alloys obtained using the friction stir welding. Tools with three different pin profile geometries were employed during this investigation at constant tool rotational speed and feed rate. Tensile tests are performed and the tensile fracture surfaces are examined using the Scanning Electron Microscope (SEM) and the obtained SEM images are used for microstructural investigations. From the experimental results, it was observed that the geometry of the tool pin plays a significant role in producing essential stirring action there by regulating the flow of the plasticized material and leading to the formation of small sized grains having equally distributed fine strengthening precipitates. These structured grains have a direct reflecting impact in increasing the hardness and mechanical properties of the fabricated joints at the nugget zone of the friction stir welded AZ80A Mg alloy joints.

scholarly journals Microstructure and Mechanical Properties of Al-3 Vol% CNT Nanocomposites Processed by High-Pressure Torsion

2017 ◽  
Vol 62 (2) ◽  
pp. 1109-1112 ◽  
Author(s):  
H. Asgharzadeh ◽  
H.S. Kim
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Pressure ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Tensile Ductility ◽  
Tensile Tests ◽  
Tensile Fracture ◽  
Tensile Fracture Surface ◽  
Transmission Electron

Abstract Al-3 vol% CNT nanocomposites were processed by high-pressure torsion (HPT) at room temperature under the pressure in the range of 2.5-10 GPa for up to 10 turns. Optical microscopy, scanning electron microscopy, and transmission electron microscopy (TEM) were used to investigate the microstructural evolutions upon HPT. Mechanical properties of the HPT-processed disks were studied using tensile tests and microhardness measurements. The results show gradual evolutions in the density, microstructure, and hardness with increasing the number of turns and applied presure. Nanostructured and elongated Al grains with an average grain thickness of ~40 nm perpendicular to the compression axis of HPT and an aspect ratio of ~3 are formed after 10 turns under 6 GPa. Evaluating the mechanical properties of the 10-turn processed Al/CNT nanocomposites indicates a tensile strength of 321 MPa and a hardness of 122 Hv. The tensile fracture surface of the Al/CNT nanocomposite mostly demonstrates a smooth fracture manner with fine dimples resulting in a low tensile ductility of ~1.5%.

Mechanism of the Flux Improving the Microstructure and Mechanical Properties of AZ91D Magnesium Alloy

2011 ◽  
Vol 194-196 ◽  
pp. 1309-1313
Author(s):  
Zhi Xiang Wang ◽  
Yang Liu ◽  
Ya Ting Le ◽  
Feng Liu
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Mechanical Performance ◽  
Energy Dispersive Spectrometer ◽  
Testing Machine ◽  
Performance Testing ◽  
Optical Microscope ◽  
Tensile Fracture ◽  
Tensile Fracture Surface ◽  
Az91d Magnesium Alloy

The microstructures and mechanical properties of AZ91D magnesium alloy produced by two kind of fluxes were analyzed by using mechanical performance testing machine, optical microscope, differential thermal analysis (DTA), X-ray diffraction(XRD), scanning electron microscope（SEM）and energy dispersive spectrometer(EDS) analysis, etc.. The results show that the comprehensive properties of AZ91D magnesium alloy produced by the new flux named NF were better than traditional flux named RJ-2. Phase Mg17Al12 was improved enormously. In addition, not only the nuclear particle A14C3 was formed, but also the grain of the alloy was refined remarkably，and the σb，σs and δ were increased eventually. The tensile fracture surface was made of deeper dimples with rolling patterns, which was relevant to the smaller microstructure.

Influence of Pearlite Interlamellar Spacing on the Deformation Behavior and Fracture Characteristics in Spring Steel 60Si2MnA

2013 ◽  
Vol 456 ◽  
pp. 388-391 ◽  
Author(s):  
Chao Lei Zhang ◽  
Ya Zheng Liu ◽  
Le Yu Zhou
Keyword(s):  
Brittle Fracture ◽  
Interlamellar Spacing ◽  
Tensile Tests ◽  
Spring Steel ◽  
Tensile Failure ◽  
Tensile Fracture ◽  
Uniaxial Tensile ◽  
Tensile Fracture Surface ◽  
Fracture Region ◽  
Electron Microscopes

Specific features of plastic deformation and tensile failure of a spring steel with systematically various pearlite fineness obtained by isothermal transformation have been investigated by uniaxial tensile tests and electron microscopes. The results indicated that pearlite interlamellar spacing has an important influence on that. The tensile fracture surface is consisted of the center plastic fracture region and the edge brittle fracture region while the interlamellar spacing is within the range 140-280nm, and is a completely brittle fracture and no necking with the further increase in interlamellar spacing to 510 nm. The deformation characteristics of pearlite in the neck regions is mainly including S-shape bend, rotation and shearing. And the data obtained suggest that the interlamellar spacing within 140-280nm can ensure the plasticity for the steel.

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