Microstructure Stability During Creep of Friction Stir Welded AZ31B Magnesium Alloy

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Michael Regev ◽  
Stefano Spigarelli ◽  
Marcello Cabibbo
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Parent Material ◽  
The Other ◽  
Creep Tests ◽  
Butt Weld ◽  
Friction Stir ◽  
Microstructure Stability ◽  
Az31b Alloy

Friction stir welding (FSW) was applied in the current study in order to butt weld AZ31B-H24 alloy plates. Creep tests were conducted both on the parent material and on the friction stir welded specimens. The microstructure of the AZ31B alloy was found to be unstable under creep conditions. In the case of friction stir welded AZ31B, the material undergoes during FSW both recrystallization and grain growth, then the exposure to temperature during creep yields an extensive additional grain growth. On the other hand, twinning and twin-induced recrystallization occur as well during creep so that ultrafine grains are being created concurrently.

scholarly journals Microstructural processes occurring during creep of friction stir welded AA2024-T3 alloy

2020 ◽  
Vol 65 (2) ◽  
pp. 53-64
Author(s):  
Michael Regev ◽  
Stefano Spigarelli
Keyword(s):  
Electron Microscopy ◽  
Aluminum Alloy ◽  
Creep Behavior ◽  
Welding Process ◽  
Parent Material ◽  
Fusion Welding ◽  
Creep Tests ◽  
Butt Weld ◽  
Friction Stir ◽  
Secondary Precipitation

The poor weldability of AA2024 aluminum alloy limits its use for industrial applications. Being a non-fusion welding process, Friction Stir Welding (FSW) seems to be a promising solution for welding this alloy. FSW was applied in the current study in order to butt weld AA2024-T3 aluminum alloy plates and to study the creep behavior of the weld. Creep tests were conducted at 250 0C and 315 0C both on the parent material and on the friction stir welded specimens. A comprehensive Transmission Electron Microscopy (TEM) study together with High Resolution Scanning Electron Microscopy (HRSEM) study and Energy Dispersive X-ray Spectroscopy (EDS) analysis were conducted in order to investigate the microstructural processes. The parent material seems to contain two kinds of Curich precipitates - coarse precipitates having the size of a few microns each and uniformly dispersed fine nanosized precipitates. However, this microstructure was found to be unstable at the temperature range of 250-315 0C, secondary precipitation was found to take place, this secondary precipitation is responsible for grain boundary decoration and the appearance of secondary rod-shaped precipitates and for some degree of coarsening of the nanosized precipitates inside the grains. TEM study yielded that the material undergoes dynamic recrystallization (DRX) during creep as well as during the FSW process. Various stages of the development of dislocation networks into a cellular dislocation structure and finally into dislocation free recrystallized grains were recorded. The friction stir welded material, which has already recrystallized during welding, undergoes DRX during creep so that ultra-fine grains are being created concurrently. Precipitation processes at the friction stir welded material occur as well during creep. The instability of the microstructure during creep and exposure to high temperature plays an important role in the analysis of the creep results. The influence of the above microstructure changes occurring during creep on the creep behavior will be referred and discussed.

scholarly journals Friction stir welding of AZ31 magnesium alloy: A review

2021 ◽  
Author(s):  
Ashish M. Desai ◽  
Bharat C. Khatri ◽  
Vivek Patel ◽  
Harikrishna Rana
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Az31 Magnesium Alloy ◽  
Friction Stir

Friction Stir Welding of Dissimilar Formed Mg Alloys (AZ31/AZ91)

2005 ◽  
Vol 486-487 ◽  
pp. 249-252 ◽  
Author(s):  
Chang Yong Lee ◽  
Won Bae Lee ◽  
Yun Mo Yeon ◽  
Seung Boo Jung
Keyword(s):  
Friction Stir Welding ◽  
Dynamic Recrystallization ◽  
Tensile Test ◽  
Intermetallic Compounds ◽  
Grain Growth ◽  
Weld Zone ◽  
Mg Alloys ◽  
Mg Alloy ◽  
Friction Stir ◽  
Az31 Mg Alloy

Friction stir welding of dissimilar formed Mg alloys(AZ31/AZ91) was successfully carried out at the limited welding conditions. In a sound joint, SZ was mainly consisted of AZ31 Mg alloy which was located the retreating side. Dynamic recrystallization and grain growth occurred and β intermetallic compounds of AZ 91 Mg alloy was not observed in SZ. BM had a higher hardness than that of the weld zone. The fracture location was not weld zone but BM of the AZ91 Mg alloy in tensile test.

scholarly journals Friction Stir Welding of AA2024-T3 plate – the influence of different pin types

2015 ◽  
Vol 6 (1) ◽  
pp. 51-55 ◽  
Author(s):  
D. Trimble ◽  
H. Mitrogiannopoulos ◽  
G. E. O'Donnell ◽  
S. McFadden
Keyword(s):  
Friction Stir Welding ◽  
Parent Material ◽  
Micro Hardness ◽  
Workpiece Material ◽  
Friction Stir ◽  
Hardness Tests ◽  
Weld Profile ◽  
Unaffected Parent ◽  
Line Defects ◽  
Tool Pin

Abstract. Some aluminium alloys are difficult to join using traditional fusion (melting and solidification) welding techniques. Friction Stir Welding (FSW) is a solid-state welding technique that can join two plates of material without melting the workpiece material. This proecess uses a rotating tool to create the joint and it can be applied to alumium alloys in particular. Macrostructure, microstructure and micro hardness of friction stir welded AA2024-T3 joints were studied. The influence of tool pin profile on the microstructure and hardness of these joints was examined. Square, triflute and tapered cylinder pins were used and results from each weldment are reported. Vickers micro hardness tests and grain size measurements were taken from the transverse plane of welded samples. Distinct zones in the macrostructure were evident. The zones were identified by transitions in the microstructure and hardness of weld samples. The zones identified across the sample were the the unaffected parent metal, the Heat Affected Zone (HAZ), the Thermo-Mechanicaly Affected Zone (TMAZ), and the Nugget Zone (NZ). Measured hardness values varied through each FSW zone. The hardness in each zone was below that of the parent material. The HAZ had the lowest hardness across the weld profile for each pin type tested. The cylindrical pin consistently produced tunnel and joint-line defects. Pin profiles with flat surface features and/or flutes produced consolidated joints with no defects.

Grain Structure Formation Ahead of Tool during Friction Stir Welding of AZ31 Magnesium Alloy

2010 ◽  
Vol 160 ◽  
pp. 313-318 ◽  
Author(s):  
Uceu Suhuddin ◽  
Sergey Mironov ◽  
H. Takahashi ◽  
Yutaka S. Sato ◽  
Hiroyuki Kokawa ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Structure Formation ◽  
Material Flow ◽  
Boundary Migration ◽  
Deformation Mode ◽  
Grain Structure ◽  
Az31 Magnesium Alloy ◽  
Structure Evolution ◽  
Friction Stir

The “stop-action” technique was employed to study grain structure evolution during friction-stir welding of AZ31 magnesium alloy. The grain structure formation was found to be mainly governed by the combination of the continuous and discontinuous recrystallization but also involved geometric effect of strain and local grain boundary migration. Orientation measurements showed that the deformation mode was very close to the simple shear associated with the rotating pin and material flow arose mainly from basal slip.

scholarly journals Feasibility of Friction Stir Welding for Joining and Microstructure Refinement in a ZK60 Magnesium Alloy

2007 ◽  
Vol 48 (12) ◽  
pp. 3140-3148 ◽  
Author(s):  
Sergey Mironov ◽  
Yoshinobu Motohashi ◽  
Tsutomu Ito ◽  
Alexandre Goloborodko ◽  
Kunio Funami ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Friction Stir ◽  
Microstructure Refinement ◽  
Zk60 Magnesium Alloy

scholarly journals Investigations on force generation and joint properties of dissimilar thickness friction stir corner welded AA 5086 alloy

2020 ◽  
Vol 40 (1) ◽  
pp. 67-74
Author(s):  
Manigandan Krishnan ◽  
Senthilkumar Subramaniam
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Welding Speed ◽  
Welding Process ◽  
Spindle Motor ◽  
Parent Material ◽  
Force Generation ◽  
Friction Stir ◽  
Current Consumption ◽  
Spindle Motor Current

The force generation, joint mechanical and metallurgical properties of friction stir corner welded non-heat treatable AA 5086 aluminum alloy are investigated in this paper. The friction stir welding process is carried out with the plate thicknesses of 6 mm and 4 mm. The welding speed, tool rotational speed and tool plunge depth were considered as the process parameters to conduct the welding experiments. The machine spindle motor current consumption and tool down force generation during friction stir welding were analyzed. The microstructures of various joint regions were observed. The tensile samples revealed the tensile strength of 197 MPa with tool rotational and welding speeds of 1,000 rev/min and 150 mm/min respectively, which is 78 % of parent material tensile strength. A maximum micro hardness of 98 HV was observed at thermomechanically joint affected zone, which was welded with tool rotation of 1,000 rev/min and welding speed of 190 mm/min.

scholarly journals 3D-Printed Tool Shoulder Design for the Analogue Modelling of Bobbin Friction Stir Weld Joint Quality

2021 ◽  
Vol 21 (1) ◽  
pp. 27-42
Author(s):  
A. Tamadon ◽  
D. J. Pons ◽  
K. Chakradhar ◽  
J. Kamboj ◽  
D. Clucas
Keyword(s):  
Friction Stir Welding ◽  
Cross Sections ◽  
Weld Joint ◽  
Flow Patterns ◽  
Friction Stir Weld ◽  
Butt Weld ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Analogue Modelling ◽  
3D Printed

Abstract A variety of tool shoulder designs comprising three families i.e. blade, spiral and circular shaped scrolls, were produced to improve the material flow and restrictions to avoid the tunnel void. The bobbin tools were manufactured by 3D printing additive manufacturing technology using solid filament. The butt weld joint was produced by each tool using plasticine as the workpiece material. The apparent surface features and bi-colour cross-sections provided a physical flow comparison among the shoulder designs. For the bobbin friction stir welding (BFSW), the tool shoulder with a three-spiral design produced the most stability with the best combination of the flow patterns on surface and cross-sections. The circular family tools showed a suitable intermixing on the surface pattern, while the blade scrolls showed better flow features within the cross-sections. The flow-driven effect of the shoulder features of the bobbin-tool design (inscribed grooves) was replicated by the 3D-printed tools and the analogue modelling of the weld samples. Similar flow patterns were achieved by dissimilar aluminium-copper weld, validating the accuracy of the analogue plasticine for the flow visualization of the bobbin friction stir welding.

Friction Stir Welding of HSLA-65 Steel for Shipbuilding

2003 ◽  
Vol 19 (03) ◽  
pp. 159-164 ◽  
Author(s):  
Paul J. Konkol ◽  
James A. Mathers ◽  
Richard Johnson ◽  
Joseph R. Pickens
Keyword(s):  
Friction Stir Welding ◽  
Salt Spray ◽  
Parent Material ◽  
Visual Examination ◽  
Ferrous Alloys ◽  
Salt Spray Corrosion ◽  
Friction Stir ◽  
Transverse Tensile ◽  
Bend Tests ◽  
Transverse Weld

HSLA-65 (ASTM A945) is a new structural steel of interest to the Navy shipbuilding community. The feasibility of joining the alloy by the friction stir welding (FSW) process was assessed. Single-pass weldments in 6.4-mm plates and two-pass weldments in 12.7-mm plates were successfully made. The FS weldments were evaluated by performing transverse tensile and bend tests; hardness, Charpy V-notch toughness, and salt spray corrosion testing; and metallographic evaluations. The weldments exhibited satisfactory transverse weld tensile strength, ductility, Charpy Vnotch toughness, and hardness. Visual examination revealed no difference in salt spray corrosion rates between the stir zone, the heat-affected zone, and the parent material. The results indicate that FSW does indeed have potential for joining ferrous alloys in shipbuilding, which should promote further efforts in this area.

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