Microstructural Evolution of Cast Mg-Al-Ca Alloy during Friction Stir Processing

2007 ◽  
Vol 539-543 ◽  
pp. 3739-3744 ◽  
Author(s):  
Da Tong Zhang ◽  
Mayumi Suzuki ◽  
Kouichi Maruyama

A thixomoulded magnesium alloy containing thermally stable Al2Ca phase was friction stir processed, and its microstructure and mechanical property were investigated. In friction stir zone, the cast structure of the base metal is replaced by fine magnesium grains containing fine dispersoides of Al2Ca. Due to the refined grain size of 0.8-1 μm, hardness of friction stir zone is higher than that of base metal. Texture was developed at top and bottom surfaces, (0002) being parallel to the plate surface, whereas (0001) plane is randomly oriented in the center of friction stir zone.

2012 ◽  
Vol 706-709 ◽  
pp. 1823-1828 ◽  
Author(s):  
J.A. del Valle ◽  
P. Rey ◽  
D. Gesto ◽  
D. Verdera ◽  
Oscar A. Ruano

The effect of friction stir processing (FSP), on the microstructure and mechanical properties of a magnesium alloy AZ61 has been analyzed. This is a widely used wrought magnesium alloy provided in the form of rolled and annealed sheets with a grain size of 45 μm. The FSP was performed with an adequate cooling device in order to increase the heat extraction and reduce the processing temperature. The final microstructure showed a noticeable grain size refinement down to values close to 1.8 μm and an important change in texture. The change in texture favors basal slip during tensile testing leading to an increase of ductility and a decrease in yield stress. The stability of the grain size and the creep behavior at high temperatures were investigated. The optimum conditions for superplastic forming were determined; however, the presence of a large amount of cavities precludes the achievement of high superplastic elongations. Additionally, these results are compared with those obtained by severe hot rolling.


2012 ◽  
Vol 05 ◽  
pp. 375-382
Author(s):  
P. ASADI ◽  
M. K. BESHARATI GIVI ◽  
G. FARAJI

Friction stir processing (FSP) is an effective tool to produce a surface composite layer with enhanced mechanical properties and modified microstructure of as-cast and sheet metals. In the present work, the mechanical and microstructural properties of as-cast AZ 91 magnesium alloy were enhanced by FSP and an AZ 91/ SiC surface nanocomposite layer has been produced using 30 nm SiC particles. Effect of the FSP pass number on the microstructure, grain size, microhardness, and powder distributing pattern of the surface developed has been investigated. The developed surface nanocomposite layer presents a higher hardness, an ultra fine grain size and a better homogeneity. Results show that, increasing the number of FSP passes enhances distribution of nano-sized SiC particles in the AZ 91 matrix, decreases the grain size, and increases the hardness significantly. Also, changing of the tool rotating direction results much uniform distribution of the SiC particles, finer grains, and a little higher hardness.


2010 ◽  
Vol 654-656 ◽  
pp. 751-754 ◽  
Author(s):  
Joseph D. Robson ◽  
Song Cui ◽  
Zhan W. Chen

Friction stir processing (FSP) of cast AM60 magnesium alloy has been studied using the breaking pin method, freezing the microstructure during the process. Strong evidence is seen that partial melting plays a key role in removing the β-Mg17Al12, whereas the manganese rich intermetallics persist during FSP. This is consistent with temperature predictions made using a process model adapted to FSP of AM60 castings that show the eutectic melting point is exceeded.


Author(s):  
Yijie Hu ◽  
Youping Sun ◽  
Jiangmei He ◽  
Dejun Fang ◽  
Jiaxin Zhu ◽  
...  

Abstract Friction stir processing is an important method for acquiring ultrafine-grained materials. In this paper, 3mm ZK60 magnesium alloy sheet was carried for friction stir processing. The best processing parameters with a small grain size and maximum mechanical properties were obtained by comparing different rotation speeds and processing speeds. Fine recrystallized grains and high-angle grain boundaries were observed in stirring zone under different processing parameters. With increasing rotation speed, the grain size and high-angle grain boundary ratio increase; while with increasing processing speed, the grain size decrease, and the ratio of high-angle grain boundaries increase. When rotation speed and processing speed are 1400 r·min-1 and 100 mm·min-1, the processing plate have the largest ultimate tensile strength are 267.52 Mpa, that reached 84.62% of the base metals, and the yield strength, elongation and grain size are 166.97 Mpa, 15.32 % and 1.12 ± 1.64 µm, respectively. The processing plate has more excellent damping performance than rolled.


2010 ◽  
Vol 654-656 ◽  
pp. 962-965 ◽  
Author(s):  
Zhan W. Chen ◽  
Song Cui ◽  
Wei Gao ◽  
Tian Ping Zhu

Castings may be used more as structural components if friction stir (FS) processing could refine the microstructures satisfactorily. For this, material flow and the formation of various microstructural regions during FS were studied. It was found that -Al dendrites and eutectic Al-Si were sheared into the thread spaces and the microstructures were significantly modified and refined. Material merely dragged into the FS zone remains microstructurally segregated. The volume of each flow was affected by rotation speed and forward speed and the reason for this is explained. Finally, textures determined together with the strain values estimated are presented to discuss further the microstructual development in various stir zones.


2016 ◽  
Vol 61 (3) ◽  
pp. 1555-1560 ◽  
Author(s):  
J. Iwaszko ◽  
K. Kudła ◽  
K. Fila ◽  
M. Strzelecka

Abstract The samples of the as-cast AM60 magnesium alloy were subjected to Friction Stir Processing (FSP). The effect of FSP on the microstructure of AM60 magnesium alloy was analyzed using optical microscopy and X-ray analysis. Besides, the investigation of selected properties, i.e. hardness and resistance to abrasion wear, were carried out. The carried out investigations showed that FSP leads to more homogeneous microstructure and significant grain refinement. The average grain size in the stirred zone (SZ) was about 6-9 μm. in the thermomechanically affected zone (TMAZ), the elongated and deformed grains distributed along flow line were observed. The structural changes caused by FSP lead to an increase in microhardness and wear resistance of AM60 alloy in comparison to their non-treated equivalents. Preliminary results show that friction stir processing is a promising and an effective grain refinement technique.


2016 ◽  
Vol 47 (5) ◽  
pp. 2201-2216 ◽  
Author(s):  
A. Tripathi ◽  
A. Tewari ◽  
A. K. Kanjarla ◽  
N. Srinivasan ◽  
G. M. Reddy ◽  
...  

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