The Effects of Heat Treatment and Cold Working on the Microstructure of Aluminum Alloys Welded by Friction Stir Welding (FSW) Technique

2011 ◽  
Vol 409 ◽  
pp. 287-292
Author(s):  
M. Mohammadtaheri ◽  
M. Haddad-Sabzevar ◽  
Mohammad Mazinani
Keyword(s):  
Grain Size ◽  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Cold Work ◽  
Base Material ◽  
Work Conditions ◽  
Weld Nugget ◽  
Hardness Profile ◽  
Friction Stir ◽  
Average Grain Size

The application of hot deformation during Friction Stir Welding (FSW) gives rise to produce a weld nugget consisting usually of dynamically recrystallized grains whose size is substantially lower than that of the base material. In the present study, several specimens with different conditions were first prepared using 2024 and 5083 aluminum alloys, which were then welded with FSW method. The microstructures of weld nugget in both series of specimens were examined using optical and scanning electron microscopes. The specimen of 2024 with anneal (O) and artificial aging (T6) conditions, and type 5083 with anneal (O), 30% and 50% cold work conditions were friction stir welded. Grain size distribution, hardness and temperature profiles in the welded zones were determined in order to obtain the relationship between the grain structure and the hardness profile in these regions. In each alloy, the average grain size in the weld nuggets was identical. The hardness of nugget zones in each alloy was the same due to their similar microstructures. According to the results obtained in this investigation, the initial microstructure showed no considerable effect on final microstructure and hardness of the weld nuggets, which this effect may be attributed to continuous dynamic recrystallization phenomenon.

Investigation of Microstructure and Mechanical Properties of Friction Stir Lap Jointed Ni Base Superalloy

2012 ◽  
Vol 724 ◽  
pp. 481-485
Author(s):  
Kuk Hyun Song ◽  
Kazuhiro Nakata
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Friction Stir Welding ◽  
Base Material ◽  
Lap Joints ◽  
Stir Zone ◽  
Inconel 600 ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size

This study evaluated the microstructure and mechanical properties of friction stir welded lap joints. Inconel 600 and SS 400 as experimental materials were selected, and friction stir welding was carried out at tool rotation speed of 200 rpm and welding speed of 100 mm/min. Applying the friction stir welding was notably effective to reduce the grain size of the stir zone, as a result, the average grain size of Inconel 600 was reduced from 20 μm in the base material to 8.5 μm in the stir zone. Joint interface between Inconel 600 and SS 400 showed a sound weld without voids and cracks. Also, the hook, along the Inconel 600 alloy from SS 400, was formed at advancing side, which directly affected an increase in peel strength. In this study, we systematically discussed the evolution on microstructure and mechanical properties of friction stir lap jointed Inconel 600 and SS 400.

Underwater dissimilar friction stir welding of aluminum alloys: Elucidating the grain size and hardness of the joints

2017 ◽  
Vol 233 (4) ◽  
pp. 763-775 ◽  
Author(s):  
Khosro Bijanrostami ◽  
Reza Vatankhah Barenji
Keyword(s):  
Grain Size ◽  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Classical Equation ◽  
Hardness Test ◽  
Traverse Speed ◽  
Welding Parameters ◽  
Friction Stir ◽  
Dissimilar Friction Stir Welding ◽  
Electron Microscopes

Underwater dissimilar friction stir welding of the AA6061 and AA7075 aluminum alloys was performed in this study. The effect of friction stir welding parameters on the grain size and hardness of the joints was studied using empirical models. The microstructure of the joints was characterized by means of light and transmission electron microscopes. The Vickers hardness test was conducted to measure the hardness of the joints. In addition, the process parameters including traverse and rotational speeds, grain size and hardness of the joints were correlated. The results revealed that the developed models predicted the hardness and grain size of the joints, precisely. Higher traverse speed and lower rotational speeds resulted in finer grain size and larger hardness. The grain boundaries and dislocations were identified as responsible for the higher hardness of the joints welded at lower heat input conditions. Moreover, the Hall–Petch relationship showed a deviation from its linear classical equation, which was due to the formation of substructures such as dislocations inside the grains.

A Study on Friction Stir Welding of Dissimilar Thin Sheets of Aluminum Alloys AA 5052–AA 6061

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Jyoti K. Doley ◽  
Sachin D. Kore
Keyword(s):  
Grain Size ◽  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Dynamic Recrystallization ◽  
Weld Line ◽  
Optical Microscope ◽  
Thin Sheets ◽  
Friction Stir ◽  
Dissimilar Welds ◽  
Tailor Welded Blank

Friction stir welding (FSW) of AA 5052 H32 to AA 6061 T6 blanks was obtained for each thicknesses of 1 mm and 1.5 mm. Successful welds were obtained at constant tool spindle speed of 1500 rpm and two tool traverse speeds of 63 mm/min and 98 mm/min. For both thicknesses, weld produced at 63 mm/min speed gives more ductility than the weld produced at 98 mm/min. Elongation prior failure of 1.5 mm thick tailor welded blank (TWB) was found to be 47% more than that of 1 mm thickness weld. Microhardness measurement of the dissimilar welds showed lower values at heat-affected zones (HAZ) on both the sides of weld line, whereas lowest hardness value was obtained at HAZ of AA 5052. Optical microscope and energy dispersive spectroscopy (EDS) analyses on the stir zone (SZ) suggest dynamic recrystallization and finer grain size with uniform mixing at the center of SZ. Intermetallic compounds are formed during welding which plays detrimental role in the fracture strength of the joint.

Synergetic Effect of ECAP and Friction Stir Welding on Microstructure and Mechanical Properties of Aluminium Sheets

2010 ◽  
Vol 667-669 ◽  
pp. 505-510
Author(s):  
Ilya Nikulin ◽  
Alla Kipelova ◽  
Sergey Malopheyev ◽  
Rustam Kaibyshev
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Friction Stir Welding ◽  
Base Metal ◽  
Synergetic Effect ◽  
Aluminum Matrix ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size

Friction stir welding (FSW) was used to join the submicrocrystalline (SMC) grained Al-Cu-Mg-Ag sheets produced by equal channel angular pressing (ECAP) followed by hot rolling (HR). The effect of SPD and FSW on the microstructure and mechanical properties in the zone of base metal, as well as in the stirred zone (SZ) were examined. In addition, effect of standard heat treatment on microstructure and mechanical properties in these zones was considered. A refined microstructure with an average grain size of ~ 0.6 m and a portion of high-angle grain boundaries (HAGBs) of ~0.67 was produced in sheets by ECAP followed by HR at 250°C. The microcrystalline grained structure with average grain size of ~2.3 mm was found in joint weld. The moderate mechanical properties were revealed in SMC sheets and joint welds. Heat treatment considerably increases strength of the base metal as well as the joint welds. The higher strength of the alloy after T6 temper is attributed to the dense precipitations of  dispersoids having plate-like shape which are uniformly distributed within aluminum matrix. It was observed that FSW can produce full strength weld both in the tempered and in the un-tempered conditions.

scholarly journals Investigation into the Dissimilar Friction Stir Welding of AA5052 and AA6061 Aluminum Alloys Using Pin-Eccentric Stir Tool

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 718 ◽  
Author(s):  
Yu Chen ◽  
He Wang ◽  
Huaying Li ◽  
Xiaoyu Wang ◽  
Hua Ding ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Material Flow ◽  
Tensile Tests ◽  
Friction Stir ◽  
Dissimilar Aluminum Alloys ◽  
Dissimilar Friction Stir Welding ◽  
Average Grain Size ◽  
Dislocation Strengthening ◽  
Onion Ring

Friction stir welding with different pin-eccentric stir tools (the pin eccentricities were 0, 0.4, and 0.8 mm, respectively) was successfully utilized for joining dissimilar aluminum alloys AA5052 and AA6061, and the influences of pin eccentricity on the microstructural evolution and mechanical properties of joints were investigated. The results showed that sound joints could be obtained by placing the hard AA6061 in the advancing side, while the welding heat input led to both the coarsening of strengthening precipitates and dynamic recrystallization and softening of the nugget zone (NZ). The application of pin eccentricity promoted the material flow in the NZ and enlarged the area of the “onion ring”. Furthermore, the average grain size and fraction of recrystallized grain in the NZ decreased as the pin eccentricity increased. All joints failed in the NZ during tensile tests, and the joint produced by the 0.8 mm-pin-eccentric stir tool performed the highest tensile strength due to the enhanced grain-boundary and dislocation strengthening.

Microstructure and Texture Evolution during Friction Stir Processing of AZ31 Mg Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 1195-1200 ◽  
Author(s):  
Ren Long Xin ◽  
Bo Li ◽  
Qing Liu
Keyword(s):  
Grain Size ◽  
Texture Evolution ◽  
Base Material ◽  
Alloy Sheet ◽  
Electron Back Scatter Diffraction ◽  
Mg Alloy ◽  
Gradual Change ◽  
Friction Stir ◽  
Az31 Mg Alloy ◽  
Average Grain Size

In this study, a well-textured AZ31 Mg alloy sheet was friction stir (FS) processed, and the microstructure and texture evolution in various regions of the processed alloy were examined by optical microscopy (OM) and electron back scatter diffraction (EBSD). The results showed that the grain size in the FS zone was significantly refined compared to that in the base material (BM). The average grain size in the thermomechanically affected zone (TMAZ) and heat-affected zone (HAZ) was comparable with that in the BM. There is a gradual change of local texture from BM to FS zone due to plastic flow together with heating input during the FS processing. The <0002> direction was roughly parallel to the cylindrical pin surface normal of the FS zone. The <0002> direction in the HAZ is similar to that in the BM, but more diffuse. The <0002> direction in the TMAZ was tilted 25~30o away from the ND and there is a distinct boundary between the FS zone and TMAZ at the advancing side which introduced an incompatibility between the FS zone and TMAZ. This might explain the fact that the transverse FS processed Mg alloys commonly fracture at the advancing side during tensile tests.

Multi-objective optimization of friction stir welding process parameters for joining of dissimilar AA5083/AA6063 aluminum alloys using hybrid approach

2016 ◽  
Vol 232 (4) ◽  
pp. 343-353 ◽  
Author(s):  
Saurabh Kumar Gupta ◽  
KN Pandey ◽  
Rajneesh Kumar
Keyword(s):  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Process Parameters ◽  
Hybrid Approach ◽  
Weld Nugget ◽  
Multi Objective Optimization ◽  
Nugget Zone ◽  
Friction Stir ◽  
Multi Objective ◽  
Dissimilar Aluminum Alloys

Joining of dissimilar aluminum alloys are widely used in automobile, aerospace and shipbuilding industries. The defect-free joining of aluminum alloys using conventional technique is a challenging task for a welding engineer. Friction stir welding has been established as one of the most promising processes for defects-free joining of aluminum alloys. In this study, a hybrid approach of grey relational analysis with principal component analysis, is applied for multi-objective optimization of process parameters for friction stir welding of dissimilar AA5083/AA6063 aluminum alloys. Three responses namely tensile strength, average hardness at weld nugget zone and average grain size at weld nugget zone, and four process parameters with three levels have been selected for the study. Taguchi method based L27 orthogonal array design matrix is used for experiments. The optimal set of process parameters using hybrid approach was found as 900 r/min of tool rotational speed, 60 mm/min of welding speed, 18 mm of shoulder diameter and 5 mm of pin diameter. Improved performance of each response was obtained from the confirmation tests at optimum level of parameters.

EXPERIMENTAL INVESTIGATION ON FRICTION STIR WELDING OF CRYOROLLED AA2219 ALUMINUM ALLOY JOINTS

2016 ◽  
Vol 24 (01) ◽  
pp. 1750001 ◽  
Author(s):  
K. KAMAL BABU ◽  
K. PANNEERSELVAM ◽  
P. SATHIYA ◽  
A. NOORUL HAQ ◽  
S. SUNDARRAJAN ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Corrosion Resistance ◽  
Friction Stir Welding ◽  
Base Material ◽  
Weld Nugget ◽  
Friction Stir ◽  
Temperature Operating ◽  
Aa2219 Aluminum Alloy ◽  
Large Clusters ◽  
Tool Pin

In this paper, experimental investigation on cryorolled aluminum AA2219-T87 plate by using friction stir welding (FSW) process is carried out. AA2219-T87 plates with a size of 200[Formula: see text]100[Formula: see text]22.4 mm were rolled and reduced to 12.2[Formula: see text]mm thickness (more than 45% of reduction in total thickness of the base material) at cryogenic temperature (operating temperature range [Formula: see text]90–[Formula: see text]30[Formula: see text]C). The cryorolled (CR) plates have reduced grain size, improved hardness and increased corrosion resistance property compared with the uncryorolled AA2219-T87 plates. FSW joints of cryorolled AA2219-T87 plates were prepared using cylindrical threaded FSW tool pin profile. Mechanical and metallurgical behaviors of friction stir welded joints were analyzed and the effects of the FSW process parameters are discussed in this paper. The variation of microhardness in the FSW joint regions were correlated with the microstructure of FSW joints. Cryorolled plate and FSW joints were tested for corrosion resistance using potentiodynamic polarization test. FSW joints shows better result during the corrosion resistance analysis compared to base AA2219-T87. The X-ray diffraction (XRD) test results showed that fine [Formula: see text]-Al grains with eutectic phase (Al2Cu) were present in the weld nugget (WN). The large clusters of strengthening precipitates were reduced in size and merged with the weld nugget portion.

Metallurgical and Mechanical Properties of Friction Stir Welded Ultra Fine Grained Steel

2007 ◽  
Vol 539-543 ◽  
pp. 3727-3732 ◽  
Author(s):  
Satoshi Hirano ◽  
Kazutaka Okamoto ◽  
S.H.C. Park ◽  
K. Aota ◽  
T. Tsukamoto
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Friction Stir Welding ◽  
Cubic Boron Nitride ◽  
Joint Effect ◽  
The Other ◽  
Friction Stir ◽  
Polycrystalline Cubic Boron Nitride ◽  
Fine Grained ◽  
Average Grain Size

Friction Stir Welding (FSW) has been applied to ultra fine grained (UFG) steel which is the plane carbon steel with the average grain size of 1mm. The plates of 5mm thickness was successfully welded using pcBN tool (polycrystalline cubic boron nitride) and the metallurgical and mechanical properties of the joint were evaluated. In the stir zone, Bainite has been formed which shows the highest harness in the joint. On the other hand, grain growth is observed in the heat affected zone. The joint effect of 88% has been obtained for UFG steel by FSW process.

Localized Corrosion Resistance of Dissimilar Aluminum Alloys Joined by Friction Stir Welding (FSW)

2016 ◽  
Vol 710 ◽  
pp. 41-46 ◽  
Author(s):  
Aline F.S. Bugarin ◽  
Fernanda Martins Queiroz ◽  
Maysa Terada ◽  
Hercílio G. De Melo ◽  
Isolda Costa
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Weight Ratio ◽  
Base Material ◽  
High Strength ◽  
Localized Corrosion ◽  
Friction Stir ◽  
Dissimilar Aluminum Alloys

2XXX and 7XXX high strength aluminum alloys are the most used materials for structural parts of aircrafts due to their high strength/weight ratio. Their joining procedure is an engineering challenge since they present low weldability. Friction Stir Welding (FSW) is a joining technology developed in the early 90 ́s. It is a solid-state welding process, without the use of fillers or gas shield, that eliminates conventional welding defects and has been considered of great interest for application in the aircraft industry. FSW of aluminum alloys results in four regions of different microstructures, specifically: the base material (BM), the heat affected zone (HAZ), the thermo-mechanically affected zone (TMAZ), and the nugget zone (NZ). The complex microstructure of the weld region leads to higher susceptibility to localized corrosion as compared to the BM even when similar alloys are joined. The welding of dissimilar alloys in its turn results in even more complex microstructures as materials with intrinsically different composition, microstructures and electrochemical properties are put in close contact. Despite the great interest in FSW, up to now, only few corrosion studies have been carried out for characterization of the corrosion resistance of dissimilar Al alloys welded by FSW. The aim of this study is to investigate the corrosion behavior of aluminum alloy 2024-T3 (AA2024-T3) welded to aluminum alloy 7475-T761 (AA7475-T761) by FSW. The evaluation was performed in 0.01 mol.L-1 by means of open circuit potential measurements, polarization techniques and surface observation after corrosion tests.

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