Ultrasonic assisted second phase transformations under severe plastic deformation in friction stir welding of AA2024

2019 ◽  
Vol 21 ◽  
pp. 100660 ◽  
Author(s):  
A.A. Eliseev ◽  
T.A. Kalashnikova ◽  
D.A. Gurianov ◽  
V.E. Rubtsov ◽  
A.N. Ivanov ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Friction Stir Welding ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
Second Phase ◽  
Friction Stir ◽  
Ultrasonic Assisted

TEM Characterization of a 7042 Aluminum FSW Joint

2012 ◽  
Vol 186 ◽  
pp. 331-334
Author(s):  
Mateusz Kopyściański ◽  
Stanislaw Dymek ◽  
Carter Hamilton
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Dislocation Density ◽  
Severe Plastic Deformation ◽  
Base Material ◽  
Friction Stir ◽  
Tem Characterization ◽  
Equiaxed Grains

This research characterizes the changes in microstructure that occur in friction stir welded extrusions of a novel 7042 aluminum alloy. Due to the presence of scandium the base material preserved the deformation microstructure with elongated grains and fairly high dislocation density. The temperature increase with simultaneous severe plastic deformation occurring during friction stir welding induced significant changes in the microstructure within the weld and its vicinity. The weld center (stir zone) was composed of fine equiaxed grains with residual dislocations and a modest density of small precipitates compared to the neighbouring thermomechanically and heat affected zones where the density of small precipitates was much higher.

scholarly journals Fatigue Behaviour of 7N01-T4 Aluminium Alloy Welded by Ultrasonic-Assisted Friction Stir Welding

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4582 ◽  
Author(s):  
Zhiqiang Zhang ◽  
Changshu He ◽  
Ying Li ◽  
Jingxun Wei ◽  
Menggang Zhai ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Residual Stresses ◽  
Ultrasonic Vibration ◽  
Fatigue Cracks ◽  
High Stress ◽  
Fatigue Behaviour ◽  
Second Phase ◽  
Friction Stir ◽  
Stress Levels ◽  
Ultrasonic Assisted

This study investigates the effects of axial ultrasonic vibration on the microstructure evolution, residual stresses distribution and fatigue fracture behaviour of a 7N01-T4 joint, and demonstrates that ultrasonic vibration can significantly promote the flow of plasticised metals, expand the stirred zone (SZ) width and refine the grain size. The longitudinal residual stresses of the joints are dominant, and the peak longitudinal residual stresses of the thermo-mechanically affected zone (TMAZ) on the advancing side (AS) (TMAZ-AS) in the ultrasonic-assisted friction stir welding (UAFSW) joint are 31.5 MPa lower than those in the friction stir welding (FSW) joint. Compared to that of FSW joints, the fatigue strength of UAFSW joints increases by 20 MPa at 107 cycles (stress ratio of R = 0.1). At high-stress levels, crack initiation occurs at the TMAZ-AS, and is mainly attributed to high residual stresses and second-phase particles. At low-stress levels, fatigue cracks are likely to initiate in the transition zone (TZ).

scholarly journals Severe Plastic Deformation and Phase Transformations in High Entropy Alloys: A Review

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 54
Author(s):  
Boris B. Straumal ◽  
Roman Kulagin ◽  
Brigitte Baretzky ◽  
Natalia Yu. Anisimova ◽  
Mikhail V. Kiselevskiy ◽  
...  
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
Single Phase ◽  
Materials Science ◽  
Bulk Solution ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy

This review discusses an area of expertise that is at the intersection of three large parts of materials science. These are phase transformations, severe plastic deformation (SPD), and high-entropy alloys (HEA). First, SPD makes it possible to determine the borders of single-phase regions of existence of a multicomponent solid solution in HEAs. An important feature of SPD is that using these technologies, it is possible to obtain second-phase nanoparticles included in a matrix with a grain size of several tens of nanometers. Such materials have a very high specific density of internal boundaries. These boundaries serve as pathways for accelerated diffusion. As a result of the annealing of HEAs subjected to SPD, it is possible to accurately determine the border temperature of a single-phase solid solution area on the multicomponent phase diagram of the HEA. Secondly, SPD itself induces phase transformations in HEAs. Among these transformations is the decomposition of a single-phase solid solution with the formation of nanoparticles of the second phase, the formation of high-pressure phases, amorphization, as well as spinodal decomposition. Thirdly, during SPD, a large number of new grain boundaries (GBs) are formed due to the crystallites refinement. Segregation layers exist at these new GBs. The concentration of the components in GBs differs from that in the bulk solid solution. As a result of the formation of a large number of new GBs, atoms leave the bulk solution and form segregation layers. Thus, the composition of the solid solution in the volume also changes. All these processes make it possible to purposefully influence the composition, structure and useful properties of HEAs, especially for medical applications.

Fabrication of Semisolid Billets of Hypereutectic Al-Si Alloy by Severe Plastic Deformation and Remelting

2012 ◽  
Vol 472-475 ◽  
pp. 323-327 ◽  
Author(s):  
Hai Xia Shi ◽  
De Hong Lu ◽  
Hui Gong ◽  
Rong Zhou
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Friction Stir Processing ◽  
Primary Silicon ◽  
Second Phase ◽  
Rich Phase ◽  
Friction Stir ◽  
Second Phase Particles ◽  
Mean Size ◽  
Silicon Particles

This paper preliminarily explored and proved the feasibility of fabricating semisolid thixoforming billets for a hypereutectic Al-Si alloy (AlSi29Fe3) by severe plastic deformation (SPD) and semisolid remelting. In this paper, friction stir processing (FSP) was used to refine the coarse primary silicon particles and needle-shaped iron-rich phase of the hypereutectic Al-Si alloy. The results show that the semisolid thixoforming billets obtained by the above route contain fine spherical Al grains with mean size of 34m, and second-phase particles (both primary silicon and iron-rich intermetallic) of less than 10m. The microstructure is ideal non-dendritic semisolid structure. Therefore, SPD and remelting is a promising technology for the fabrication of semisolid thixoforming billets of the hypereutectic Al-Si alloy.

Precipitation-dependent corrosion analysis of heat treatable aluminum alloys via friction stir welding, a review

2021 ◽  
pp. 095440622110036
Author(s):  
Tanveer Majeed ◽  
Yashwant Mehta ◽  
Arshad N Siddiquee
Keyword(s):  
Plastic Deformation ◽  
Corrosion Resistance ◽  
Friction Stir Welding ◽  
Severe Plastic Deformation ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Behaviour ◽  
Al Alloys ◽  
Friction Stir ◽  
Precipitate Strengthening

Although the various advantages of novel Friction stir welding (FSW) process; the weld surfaces are subjected to various serious problems such as lower corrosion resistance, high susceptibility to stress corrosion cracking and poor joint fatigue strength due to complex material flow and severe plastic deformation during the welding process. Corrosion behaviour of friction stir welded (FSWed) precipitate strengthening Al alloys have significant impact on metallurgical and electrochemical properties of structures. In FSW of precipitate strengthening Al alloys the localized heat input and severe plastic deformation creating appreciable changes in microstructure and modifies the microchemistry and metallurgical characteristics of precipitates. The heterogeneous distribution of precipitates and precipitate free zones (PFZs) along the grain boundaries leads to variation in electrochemical behaviour across the weld zones and hence increasing the susceptibility of weld surface to various corrosion attacks such as intergranular corrosion, pitting corrosion, exfoliation corrosion, stress corrosion cracking and galvanic corrosion. However, the corrosion resistance of FSWed joints can be improved either by reducing the size or redissolve the coarsened precipitates within the joint or modifying the microchemistry by controlling the size, location and distribution of precipitates which largely determine the corrosion rate of the weld surfaces. Consequently, it is imperative to address the influence of material modifications during FSW on corrosion behaviour of weld surface. This review paper addresses the precipitate dependent corrosion behaviour of FSWed joints of heat treatable/precipitate strengthening Al alloys and the various effective methods either to reduce or eliminate the effect of corrosion attack in FSWed joints of heat treatable Al alloys.

Numerical Simulation of Plunge Force During the Plunge Phase of Friction Stir Welding and Ultrasonic Assisted FSW

2008 ◽  
Author(s):  
Kwanghyun Park ◽  
Bongsuk Kim ◽  
Jun Ni
Keyword(s):  
Numerical Simulation ◽  
Friction Stir Welding ◽  
High Frequency ◽  
Hybrid Welding ◽  
Ultrasonic Vibrations ◽  
Welding Quality ◽  
Friction Stir ◽  
Ultrasonic Assisted ◽  
Welding Force ◽  
Welding Technique

Ultrasonic assisted friction stir welding (UaFSW) is an hybrid welding technique, where high frequency vibration is superimposed on the movement of a rotating tool. The benefit of using ultrasonic vibration in the FSW process refers to the reduction in the welding force and to the better welding quality. The UaFSW system is being developed and its mechanism needs to be understood using both the experiments and the numerical simulations. In this paper, FE simulations of FSW and UaFSW using ABAQUS/Explicit were carried out to examine plunge forces during the plunge phase of FSW and UaFSW, respectively. First, the simulations of the conventional FSW process were validated. Then, simulation of UaFSW process was performed by imposing sinusoidal horizontal ultrasonic vibrations on the tool.

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