Effect of Hot Rolling and Equal-Channel Angular Pressing on Generation of Globular Microstructure in Semi-Solid Mg-3%Zn Alloy

2014 ◽  
Vol 217-218 ◽  
pp. 381-388 ◽  
Author(s):  
Łukasz Rogal ◽  
Frank Czerwiński ◽  
Lidia Litynska-Dobrzyńska ◽  
Piotr Bobrowski ◽  
Anna Wierzbica-Miernik ◽  
...  

A combination of hot rolling and equal channel angular pressing (ECAP) was explored to generate globular microstructures in the Mg-3%Zn alloy after re-heating to the semisolid state. It was found that the single-step deformation of as-cast alloy via hot rolling at 350°C with a thickness reduction of 50% refined the alloy microstructure by creating deformation bands of the Mg (α) phase with a size of the order of tenths of micrometers. After re-heating to 630 °C, the microstructure transformed into spheroidal morphologies with an average globule size of 82 μm. An additional deformation of the hot-rolled alloy by the ECAP method at 250 °C further refined the alloy microstructure to sub-micrometer grains of lath and equiaxed shapes. After re-heating of this microstructure to 630 °C the average globule size reached 62 μm, which is roughly 25% smaller than that achieved for the hot-rolled precursor. The role of strain-induced melt activation (SIMA) techniques in generation of globular morphologies in Mg-based alloys after partial re-melting is discussed.

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5117
Author(s):  
Yanhuai Wang ◽  
Xin Li ◽  
I. V. Alexandrov ◽  
Li Ma ◽  
Yuecheng Dong ◽  
...  

In the present study, the unique bimodal grain size distribution microstructure with the ultrafine substrate and embedded macro grains was fabricated by a traditional hot-rolling process in a novel low-cost Ti-2Fe-0.1B titanium alloy, which possesses a good combination of strength (around 663 MPa) and ductility (around 30%) without any post heat treatment. Meanwhile, the mechanical behavior and corrosion resistance of hot-rolled Ti-2Fe-0.1B alloy after equal channel angular pressing (ECAP) deformation were studied. Results indicated that the average grain size decreased to 0.24 μm after 4 passes ECAP deformation, which led to the enhancement of tensile strength to around 854 MPa and good ductility to around 15%. In addition, corrosion resistance was also improved after ECAP due to the rapid self-repairing and thicker passivation film. Our study revealed that the novel low-cost titanium alloy after hot-rolling and ECAP could be used instead of Ti-6Al-4V in some industrial applications due to similar mechanical behavior and better corrosion resistance.


2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Eka Febriyanti ◽  
Dedi Priadi ◽  
Rini Riastuti

Cu-Zn 70/30 alloy has properties that is relatively soft, ductile, and easy to perform by cold working. However, cold working has the disadvantage that require equipment which has higher loading capacity to generate strength and higher density thus increasing of machining cost. In addition, strain hardening phenomenon due to cold working process resulted in decreasing of ductility material. Therefore, it is necessary alternative fabrication processes to optimize the mechanical properties of Cu-Zn alloy 70/30 that with the TMCP method. TMCP is metal forming material by providing large and controlled plastic strain to the material. TMCP using the deformation percentage variation that 32.25%, 35.48%, and 38.7% from hot rolled research at 500°C temperature in double pass reversible which performed on Cu-Zn 70/30 plate. By tensile testing using universal testing machine can be seen that the Cu-Zn 70/30 alloy on 32.25% degree of deformation, both of UTS and YS respectively are 505 MPa and 460 MPa. Whereas from examination of thickness and density deformation bands by FE-SEM shows denser and thicker deformation band proportional with increasing of deformation degree.Moreover, the values of tensile strength at the edge of the area and the center is directly proportional to the density and thickness of the deformation band.AbstrakPaduan Cu-Zn 70/30 memiliki sifat yang relatif lunak, ulet, dan mudah dilakukan pengerjaan dingin. Namun, pengerjaan dingin memiliki kekurangan yaitu membutuhkan peralatan yang memiliki kapasitas pembebanan tinggi untuk menghasilkan kekuatan dan kepadatan tinggi sehingga meningkatkan biaya permesinan. Selain itu, fenomena pengerasan regang akibat proses pengerjaan dingin menghasilkan penurunan keuletan material. Oleh karena itu, diperlukan alternatif proses fabrikasi untuk mengoptimalkan sifat mekanik paduan Cu-Zn 70/30 salah satunya dengan metode TMCP. TMCP merupakan suatu proses perubahan bentuk suatu material dengan cara memberikan regangan plastis yang besar dan terkontrol terhadap material. TMCP dengan menggunakan variasi persentase deformasi sebanyak 32,25%, 35,48%, dan 38,70% dari penelitian canai hangat di suhu 500oC secara double pass reversible dilakukan pada pelat paduan Cu-Zn 70/30. Dengan melakukan pengujian tarik menggunakan mesin uji tarik universal testing machine dapat dilihat bahwa pada material paduan Cu-Zn 70/30 pada derajat deformasi 32,25% menghasilkan nilai UTS dan YS masing-masing sebesar 505 MPa dan 460 MPa. Sedangkan dari hasil pengamatan ketebalan dan kerapatan deformation band menggunakan FE-SEM menunjukkan deformation band yang lebih rapat dan lebih tebal sebanding dengan semakin meningkatnya derajat deformasi. Selain itu, nilai kekuatan tarik pada daerah tepi dan tengah berbanding lurus dengan kerapatan dan ketebalan deformation band.Keywords: 70/30 Cu-Zn alloy, warm rolled, deformation degree, deformation bands


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.


Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1678 ◽  
Author(s):  
Chun Chiu ◽  
Hong-Min Huang

Mg97Zn1Y2 (at %) alloy with a long period stacking ordered (LPSO) phase has attracted a great deal of attention due to its excellent mechanical properties. It has been reported that this alloy could be fabricated by warm extrusion of rapid solidified alloy powders. In this study, an alternative route combining mechanical milling and equal channel angular pressing (ECAP) was selected to produce the bulk Mg97Zn1Y2 alloy. Microstructural characterization, mechanical properties and corrosion behavior of the ECAP-compacted alloys were studied. The as-cast alloy contained α-Mg and LPSO-Mg12Zn1Y1 phase. In the as-milled powder, the LPSO phase decomposed and formed Mg24Y5 phase. The ECAP-compacted alloy had identical phases to those of the as-milled sample. The compacted alloy exhibited a hardness of 120 HV and a compressive yield strength of 308 MPa, which were higher than those of the as-cast counterpart. The compacted alloy had better corrosion resistance, which was attributed to the reduced volume fraction of the secondary phase resulting in lower microgalvanic corrosion in the compacted alloy. The increase in Y content in the α-Mg matrix also contributed to the improvement of corrosion resistance.


2006 ◽  
Vol 503-504 ◽  
pp. 823-828 ◽  
Author(s):  
Y. Choi ◽  
Nam Ihn Cho ◽  
Hyoung Seop Kim ◽  
Sun Ig Hong

Effect of equal-channel angular pressing (ECAP) on the corrosion and mechanical properties of Cu-35%Zn alloy were studied. Two types of feed direction were selected. One is parallel pass and the other is 180°degree rotated ECAP pass after each pass. Both ECAP passes made texture in each specimen in which shear band with 45 degree on transverse direction and twins exist. The specimen prepared by parallel ECAP pass has finer shear band. Relative amount of twins to shear band on the microstructure becomes decrease with number of ECAP pass. Microhardness increased from 75 Hv to 210 Hv by ECAP. The corrosion potential and rate of the ECAPed Cu-35%Zn alloys in aerated aqueous 1 M-H2SO4 solution were –92.3 mVSHE and 3.72x10-2 A/cm2 for route- A and –38.6 mVSHE and 5.08x10-2 A/cm2 for route-C, respectively. The corrosion potential and rate of depended on the feed direction and number of pass.


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