Influence of Grain Size and Microstructure on Oxidation Rates in Titanium Alloy Ti-6Al-4V Under Superplastic Forming Conditions

2004 ◽  
Vol 13 (6) ◽  
pp. 727-734 ◽  
Author(s):  
Franna Pitt ◽  
M. Ramulu
2014 ◽  
Vol 6 ◽  
pp. 563047
Author(s):  
Jiang Shaosong ◽  
Li Baoyong ◽  
Liu Yang ◽  
Zhang Kaifeng

The process combining laser beam welding, superplastic forming, anddiffusion bonding (LBW/SPF/DB) was performed to fabricate the TA15 titanium alloy sandwich structure with square grid. The microstructure of different regions before and after superplastic forming was also analyzed. The results showed that the laser welded joints of core structure own good superplastic formability under the condition that the laser welding parameters were optimized. The microstructure near the fusion line is columnar crystal and inside the columnar crystal the acicular martensite appeared. The heat-affected zone is relatively narrow and with no obvious grain growth. At 925°C, under the condition thatthe loading-time curve was optimized, the external outline of the LBW/SPF/DB formed hollow four-layer sandwich structure is clear and the strengthened ribs areupright. It shows good diffusion bonding quality between the ribs and panels. And the bonded ratio between the upright ribs which rely on each other is above 90%. After superplastic forming, the grain size of the TA15 workpieceincreases but remains equiaxed grain. The grain size of laser welded joints also significantly grew up, and the heat-affected zone almost disappeared in this zone. The typical cast microstructure of rapid cooling turned to be the deformed microstructure, creating a better overall performance of the two-state organizations.


2012 ◽  
Vol 735 ◽  
pp. 409-414 ◽  
Author(s):  
Rinat V. Safiullin

The paper describes the results of long-term investigations on the development of the technology of superplastic forming and pressure welding (SPF/PW) conducted at the Institute for Metals Superplasticity Problems, Russian Academy of Sciences for producing standard articles of aero-space engineering, such as hollow blades, wing and shell panels. The process of solid state joint formation in titanium alloy sheets during SPF was studied. Different investigation techniques were developed. The results of the mechanical and fatigue testing as well as non-destructive inspection of hollow blades are presented. The prospects of the development of the SPF/PW technology are considered and the latest results are discussed.


2010 ◽  
Vol 97-101 ◽  
pp. 153-157
Author(s):  
Tao Wang ◽  
Hong Zhen Guo ◽  
Jian Hua Zhang ◽  
Ze Kun Yao

The microstructures and room temperature and 600°C tensile properties of Ti-5.8Al-4.0Sn-4.0Zr-0.7Nb -0.4Si-1.5Ta alloy after isothermal forging have been studied. The forging temperature range was from 850°C to 1075°C, and the constant strain rate of 8×10-3/S-1 was adopted. With the increase of forging temperature, the volume fraction of primary α phase decreased and the lamellar α phase became thicker when the temperatures were in range of 850°C -1040°C; The grain size became uneven and the α phase had different forms when the forging temperature was 1040°C and 1075°C respectively; The tensile strength was not sensitive to the temperature and the most difference was within 20MPa. Tensile strength and yield strength attained to the maximum when temperature was 1020°C; the ductility decreased with the increase of forging temperature, and this trend became more obvious if forging temperature was above the β-transus temperature.


2016 ◽  
Vol 43 (8) ◽  
pp. 0802005
Author(s):  
刘浩东 Liu Haodong ◽  
胡芳友 Hu Fangyou ◽  
崔爱永 Cui Aiyong ◽  
戴京涛 Dai Jingtao ◽  
黄飞 Huang Fei ◽  
...  

2012 ◽  
Vol 43 (9) ◽  
pp. 786-788 ◽  
Author(s):  
R.V. Safiullin ◽  
A.A. Kruglov ◽  
A.Kh. Akhunova ◽  
A.R. Safiullin ◽  
S.V. Dmitriev

2012 ◽  
Vol 581-582 ◽  
pp. 777-781
Author(s):  
Ya Qiang Tian ◽  
Ying Li Wei ◽  
Hong Liang Hou ◽  
Xue Ping Ren

The effect of hydrogenation on structure and properties of TC21 alloy by die forming and sintering using hydrogenated powder was researched by means of the room-temperature die forming and sintering in protection air to produce titanium alloy. The results show that the structure of TC21 titanium sintered body using hydrogenated powder with hydrogen content of 0.39 wt% by die forming and sintering is thinner and the density is higher than the others. The compression strength and compressive yield strength of TC21 sintered body with hydrogen content of 0.39 wt% are well. With hydrogen content increasing, the structure of TC21 production using hydrogenated powder by die forming and sintering gets well and the grain size becomes smaller. After annealing, the structure of TC21 titanium production gets more uniformity and refinement obviously, and the hydrogen content of TC21 alloy safety state is achieved. In the end, the density and mechanical property of TC21 titanium alloy sintered body with hydrogen content of 0.39wt % is the best.


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.


Author(s):  
M. V. Zhidkov ◽  
A. E. Ligachev ◽  
Yu. R. Kolobov ◽  
G. V. Potemkin ◽  
G. E. Remnev

The study covers the topography and structural phase state of VT1-0 and VT6 submicrocrystalline titanium alloy subsurface layers irradiated by high power pulsed carbon ion beams (ion energy is 250 keV, pulse duration is ~100 ns, pulse current density is 150–200 A/cm2; surface energy density of a single pulse is j ~ 3 J/cm2 when irradiating VT1-0 titanium alloy samples and j ~ 1 J/cm2 when processing VT6 titanium alloy samples; pulse number is 1, 5, 10, and 50). The surface of samples was subjected to preliminary mechanical grinding and polishing before irradiation. It was shown that surface defects are formed on the surface of the alloys after irradiation, namely craters of different shapes and geometries with a diameter from fractions of a micron to 80–100 μm. At the same time, the grain structure in the subsurface layer becomes more homogeneous in terms of grain size and equiaxial properties. The initial state of titanium alloys is characterized by a fairly homogeneous structure with an average grain size of ~0,31 μm for VT1-0 and ~0,9 μm for VT6. After one irradiation pulse, grain growth to 0,54 μm in the transverse direction is observed in the subsurface layer of the VT1-0 alloy (j ~ 3 J/cm2), while grain size decreases to ~ 0,54 μm in the VT6 alloy (j ~ 1 J/cm2). After 50 pulses, the average grain size in the subsurface layer reaches ~2,2 μm for the VT1-0 alloy and ~1,6 μm for VT6. It should be noted that a rather uniform structure with equiaxed grains is formed as early as after treating with 1 high power ion beam pulse.


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