Enhancing Strength and Maintaining Ductility of Mg-3%Li-1%Sc Alloy by Equal Channel Angular Pressing

2010 ◽  
Vol 667-669 ◽  
pp. 839-844
Author(s):  
Hua Jie Yang ◽  
X.H. Shao ◽  
S.X. Li ◽  
Shi Ding Wu ◽  
Z.F. Zhang

Equal channel angular pressing (ECAP) has been conducted on as-cast Mg-3%Li-1%Sc alloy for four-passes to study the microstructure uniformity and tensile properties. After ECAP, the microstructure become muddled, contains about 65% of deformed coarse grains with abundant low angle grain boundaries and about 35% of recrystallized small grains. Meanwhile, a strong basal texture is formed in the ECAP sample. The texture type of the recrystallized grains and the deformed grains are the same, however, the texture strength of the recrystallized grains is much lower than the deformed ones. Tensile strength is improved effectively and the elongation is maintained after ECAP. The increment of strength results from the microstructure refinement and residual dislocations produced by ECAP, while the recovery of ductility may be attributed to a shear type texture formed in the alloy during ECAP.

2010 ◽  
Vol 667-669 ◽  
pp. 421-426 ◽  
Author(s):  
M.X. Yang ◽  
Gang Yang ◽  
Zheng Dong Liu ◽  
Cun Yu Wang ◽  
C.X. Huang

An 18Ni (C-250) maraging steel was successfully processed by equal channel angular pressing (ECAP) for a single pass at room temperature. Microstructural observations showed that the martensite laths of 18Ni maraging steel were elongated to more narrow bands with a width of 100-200 nm after ECAP deformation. After ageing treatment, many nano-sized precipitates distributed uniformly within the refined martensite lathes. In comparison with the tensile strength (1940 MPa) of general used steel (solution + aging treatment), the tensile strength of the sample processed by ECAP and subsequent aging treatment was enhanced for more than 100 MPa (above 2050 MPa). The enhancement of tensile properties was attributed to microstructural refinement and uniformly distributed nano-precipitates.


2006 ◽  
Vol 114 ◽  
pp. 91-96 ◽  
Author(s):  
Maxim Yu. Murashkin ◽  
M.V. Markushev ◽  
Julia Ivanisenko ◽  
Ruslan Valiev

The effects of equal channel angular pressing (ECAP), further heat treatment and rolling on the structure and room temperature mechanical properties of the commercial aluminum alloys 6061 (Al-0.9Mg-0.7Si) and 1560 (Al-6.5Mg-0.6Mn) were investigated. It has been shown that the strength of the alloys after ECAP is higher than that achieved after conventional processing. Prior ECAP solution treatment and post-ECAP ageing can additionally increase the strength of the 6061 alloy. Under optimal ageing conditions a yield strength (YS) of 434 MPa and am ultimate tensile strength (UTS) of 470 MPa were obtained for the alloy. Additional cold rolling leads to a YS and UTS of 475 and 500 MPa with 8% elongation. It was found that the post-ECAP isothermal rolling of the 1560 alloy resulted in the formation of a nano-fibred structure and a tensile strength (YS = 540 MPa and UTS = 635 MPa) that has never previously been observed in commercial non-heat treatable alloys.


2008 ◽  
Vol 584-586 ◽  
pp. 960-965 ◽  
Author(s):  
Tamara Kravchenko ◽  
Alexander Korshunov ◽  
Natalia Zhdanova ◽  
Lev Polyakov ◽  
Irina Kaganova

Annealed oxygen-free and tough-pitch copper samples have been processed by equalchannel angular pressing (ECAP) by route BC. The samples included 8 x 8 mm section pieces and a 40 mm diameter bar. Thermal stability was assessed based on the changes in the standard mechanical properties (conventional yield strength, tensile strength, elongation, proportional elongation and contraction) after annealing at different temperatures for 1 hour. Thermal stability of the same grade of material has been found to be different for different batches and to depend on the structural conditions of deformed material. The zone of thermal stability for copper of the two grades of interest does not depend on the material’s chemical composition.


2004 ◽  
Vol 449-452 ◽  
pp. 645-648
Author(s):  
Si Young Chang ◽  
Sang Woong Lee ◽  
Jin Chun Kim ◽  
Young Seok Kim ◽  
Dong Hyuk Shin

The commercial AZ31 and AZ61 Mg alloys were subjected to equal channel angular pressing (ECAP) after hot rolling at 673 K. The hot-rolled AZ31 alloy could be ECA pressed at 493 K. The 4 ECA pressed AZ31 alloy revealed the microstructure of dynamically recrystallized grains with a grain size in range of 1 to 10μm. Despite the dynamic recrystallization during ECAP at higher temperatures ( > 1/2 Tm), the yield stress and tensile strength of AZ31 and AZ61 alloys drastically increased after 1 pressing. The yield stress gradually decreased with increasing the number of pressings, which contrasts with the behavior of the ECA pressed Al and Fe alloys, while the tensile strength increased slightly. In particular, the alloys showed nearly 3 times higher elongation than as-annealed one after 4 ECAPs, without sacrificing the tensile strength. These tensile deformation characteristics were explained based on the observation of the deformed microstructure in the vicinit of fracture surface.


Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1157
Author(s):  
Lisa-Marie Rymer ◽  
Thomas Lindner ◽  
Philipp Frint ◽  
Martin Löbel ◽  
Thomas Lampke

Single-phase, face-centered cubic (FCC) high-entropy alloys (HEA) are promising materials for future applications. In order to improve the mechanical properties, especially the tensile strength of these materials, this study focuses on the combination of spark plasma sintering (SPS) and equal-channel angular pressing (ECAP). The initial fine-grained microstructure produced by SPS is further refined by ECAP in a 90°-die. Optical microscopy and electron backscatter diffraction (EBSD) confirm this considerable grain refinement, leads to a grain size below 1 µm after 1 ECAP pass. An alternating arrangement of fine-grained areas and much coarser regions, aligned under an angle of approximately 27°, is found. Moreover, a first microstructural investigation of the twin structure is conducted. The mechanical behavior was investigated by hardness measurements and tensile testing. Both the hardness and tensile strength are remarkably increased after ECAP. In contrast, the uniform elongation and elongation at fracture are significantly reduced due to the strengthening mechanisms of strain hardening and grain refinement. It is concluded that the combination of SPS and ECAP is an attractive approach for designing (ultra)fine-grained HEAs with superior properties. The investigated techniques could be applied to understand the underlying microstructural mechanisms.


2006 ◽  
Vol 426 (1-2) ◽  
pp. 305-313 ◽  
Author(s):  
D.R. Fang ◽  
Z.F. Zhang ◽  
S.D. Wu ◽  
C.X. Huang ◽  
H. Zhang ◽  
...  

2011 ◽  
Vol 682 ◽  
pp. 49-54
Author(s):  
Bin Chen ◽  
Chen Lu ◽  
Dong Liang Lin ◽  
Xiao Qin Zeng

The Mg96Y3Zn1 alloy processed by equal channel angular pressing has been investigated. It was found that the Mg96Y3Zn1 alloy processed by ECAP obtained ultrafine grains and exhibits excellent mechanical properties. After ECAP, the average grain size of Mg96Y3Zn1 alloy refined to about 400 nm. The highest strengths with yield strength of 381.45MPa and ultimate tensile strength of 438.33MPa were obtained after 2 passes at 623K. It was found that cracks were preferentially initiated and propagated in the interior of X-phase during the tensile test. As a result, the elongation of alloy is decreased with pass number increasing.


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