scholarly journals Influence of Plastic Deformation and Aging Process on Microstructure and Tensile Properties of Cast Ti-6Al-2Sn-2Zr-2Mo-1.5Cr-2Nb-0.1Si Alloy

2021 ◽  
Vol 11 (02) ◽  
pp. 11-20
Author(s):  
Mostafa S. S. El-Deeb ◽  
Khaled M. Ibrahim ◽  
S. S. Mohamed ◽  
Ramadan N. Elshaer
Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2742
Author(s):  
Furong Chen ◽  
Chenghao Liu

To improve the loose structure and serious porosity of (Al–Zn–Mg–Cu) 7075 aluminum alloy laser-welded joints, aging treatment, double-sided ultrasonic impact treatment (DSUIT), and a combination of aging and DSUIT (A–DSUIT) were used to treat joints. In this experiment, the mechanism of A–DSUIT on the microstructure and properties of welded joints was analyzed. The microstructure of the welded joints was observed using optical microscopy, scanning electron microscopy, and electron backscatter diffraction (EBSD). The hardness and tensile properties of the welded components under the different processes were examined via Vickers hardness test and a universal tensile testing machine. The results showed that, after the aging treatment, the dendritic structure of the welded joints transformed into an equiaxed crystal structure. Moreover, the residual tensile stress generated in the welding process was weakened, and the hardness and tensile strength were significantly improved. After DSUIT, a plastic deformation layer of a certain thickness was generated from the surface downward, and the residual compressive stress was introduced to a certain depth of the joint. However, the weld zone unaffected by DSUIT still exhibited residual tensile stress. The inner microhardness of the joint surface improved; the impact surface hardness was the largest and gradually decreased inward to the weld zone base metal hardness, with a small improvement in the tensile strength. Compared with the single treatment process, the microstructural and mechanical properties of the welded joint after A–DSUIT were comprehensively improved. The microhardness and tensile strength of the welded joint reached 200 HV and 615 MPa, respectively, for an increase of 45.8% and 61.8%, respectively. Observation of the fractures of the tensile specimens under the different treatment processes showed that the fractures before the aging treatment were mainly ductile fractures while those after were mainly brittle fractures. After DSUIT of the welded joints, a clear and dense plastic deformation layer was observed in the fracture of the tensile specimens and effectively improved the tensile properties of the welded joints. Under the EBSD characterization, the larger the residual compressive stress near the ultrasonic impact surface, the smaller the grain diameter and misorientation angle, and the lower the texture strength. Finally, after A–DSUIT, the hardness and tensile properties improved the most.


Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1533
Author(s):  
Haichao Zhang ◽  
Xufeng Wang ◽  
Huirong Li ◽  
Changqing Li ◽  
Yungang Li

The molecular dynamics (MD) method was used to simulate and calculate the segregation energy and cohesive energy of Cu atoms at the Σ3{111}(110) and Σ3{112}(110) grain boundaries, and the tensile properties of the BCC-Fe crystal, with the grain boundaries containing coherent Cu clusters of different sizes (a diameter of 10 Å, 15 Å and 20 Å). The results showed that Cu atoms will spontaneously segregate towards the grain boundaries and tend to exist in the form of large-sized, low-density Cu clusters at the grain boundaries. When Cu cluster exists at the Σ3{111}(110) grain boundary, the increase in the size of the Cu cluster leads to an increase in the probability of vacancy formation inside the Cu cluster during the tensile process, weakening the breaking strength of the crystal. When the Cu cluster exists at the Σ3{112}(110) grain boundary, the Cu cluster with a diameter of 10 Å will reduce the strain hardening strength of the crystal, but the plastic deformation ability of the crystal will not be affected, and the existence of Cu clusters with a diameter of 15 Å and 20 Å will suppress the structural phase transformation of the crystal, and significantly decrease the plastic deformation ability of the crystal, thereby resulting in embrittlement of the crystal.


1994 ◽  
Vol 364 ◽  
Author(s):  
Y. Yang ◽  
W. Yan ◽  
J. N. Liu ◽  
S. Hanada

AbstractForging processes at two different temperatures are performed to examine the relation between the microstructure and room temperature tensile properties in a Ce doped Fe3Al-based alloy. Results show that the microstructure and the ductility are sensitive to the forging temperature before annealing treatment. Higher yield strength and ductility can be obtained through forging at a relatively low temperature of 750°C followed by annealing at 800°C and 500°C. It is suggested that the formation of non-equilibrium grain boundaries and banded subgrains within carbide-free areas along grain boundaries enhances the local plastic deformation and results in the improvement of ductility. During the initial deformation at room temperature <111> slip is predominant for both microstructures.


2006 ◽  
Vol 321-323 ◽  
pp. 636-639
Author(s):  
Sang Young Kim ◽  
Hyung Ick Kim ◽  
Chang Sung Seok ◽  
Jae Kwan Lee ◽  
Jin Yong Mo ◽  
...  

Used pipes in various mechanisms and structures are produced from raw material by extruding and drawing. The properties such as yield strength, tensile strength, and elongation of a pipe produced by these methods are different from the properties of their raw material. But designers use the properties of the raw material because the actual properties of the pipes are difficult to obtain from testing. Also, the pipe is used after it has been bent in a complex manner and cut to fit it to mechanisms and structures. The bending process, especially, induces deformation of the pipe’s section and residual stress, which are involved in the plastic deformation of the bended pipes. This residual stress affects the pipe’s properties, including its fatigue life. Therefore, it is very important to understand the residual stress of a material. But, the distribution of residual stress of a U-shaped pipe, which is examined in this study, is very complicated and cannot be measured exactly.


2014 ◽  
Vol 794-796 ◽  
pp. 802-806 ◽  
Author(s):  
Yuji Kume ◽  
Shinichiro Ota ◽  
Makoto Kobashi ◽  
Naoyuki Kanetake

Cast AlFe alloys containing several percent iron have low ductility because of their brittle precipitates. Therefore, precipitate refinement is very important for improving their mechanical properties. In recent decades, severe plastic deformation processes have been developed to achieve this grain refinement. For example, our previously proposed severe plastic deformation process, called compressive torsion, is quite effective for not only grain refinement but also precipitate refinement even in brittle materials. In the present work, precipitate refinement of cast Al—Fe alloys by compressive torsion and the resulting improvements in their tensile properties were investigated. Compressive torsion with various numbers of revolutions was applied to Al—Fe alloys at 373 K. Then, the alloys were subjected to tensile testing at room temperature, 473 K, and 573 K. The obtained experimental results indicated that the initial eutectic microstructure of the alloys disappeared after the compressive torsion processing. All large precipitates with sizes of more than 200 μm were refined, and their sizes were reduced to several tens of micrometers. Furthermore, these refined precipitates were dispersed homogenously in the alloy microstructure. In result, the tensile properties of the alloys, namely, their strength and elongation, were improved remarkably. In particular, the elongation reached more than 30% at room temperature.


2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Yan Ma ◽  
Muxin Yang ◽  
Ping Jiang ◽  
Fuping Yuan ◽  
Xiaolei Wu

2018 ◽  
Vol 775 ◽  
pp. 434-440
Author(s):  
Sang Hoon Kim ◽  
Jong Un Lee ◽  
Byoung Gi Moon ◽  
Sung Hyuk Park

This study investigated the microstructure and tensile properties of three indirectly extruded Mg-Sn-Al-Zn alloys: Mg-11Sn-1Al-1Zn (TAZ1111), Mg-8Sn-4Al-1Zn (TAZ841), and Mg-8Sn-1Al-4Zn (TAZ814). The investigation results revealed that in all the alloys, Mg2Sn particles formed during solidification were not fully dissolved by homogenization treatment. These undissolved particles enhanced the dynamic recrystallization behavior through a particle-stimulated nucleation phenomenon. As a result, all the extruded alloys exhibited a fully dynamically recrystallized microstructure. The tensile yield strength (TYS) of the extruded alloys was in the following order: TAZ1111 > TAZ841 > TAZ814. In contrast, the elongation of the alloys was in the opposite order: TAZ814 > TAZ841 > TAZ1111. The highest TYS of the TAZ1111 alloy was attributed mainly to the smaller grain size and more abundant Mg2Sn precipitates resulting from a higher Sn content. However, the ultimate tensile strengths of all the extruded alloys were nearly the same because the Al or Zn atoms dissolved in the TAZ841 and TAZ814 alloys improved the strain hardening rate during plastic deformation.


2018 ◽  
Author(s):  
S. Yu. Tarasov ◽  
A. V. Filippov ◽  
S. V. Fortuna ◽  
A. V. Vorontsov

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