scholarly journals Comparison of the Cracking Behavior of Powder Metallurgy and Ingot Metallurgy Ti-5Al-5Mo-5V-3Cr Alloys during Hot Deformation

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 457 ◽  
Author(s):  
Qinyang Zhao ◽  
Fei Yang ◽  
Rob Torrens ◽  
Leandro Bolzoni
Keyword(s):  
Powder Metallurgy ◽  
Deformation Temperature ◽  
Shear Fracture ◽  
Ingot Metallurgy ◽  
Hot Workability ◽  
Compression Tests ◽  
Cracking Behavior ◽  
Comparison Results ◽  
Edge Cracking ◽  
Brittle Cleavage Fracture

The hot workability of metallic materials is significantly dependent on its ability to form plastic without cracking and fracturing. In this work, the cracking behavior of powder metallurgy (PM) Ti-5Al-5Mo-5V-3Cr (Ti-5553) alloy, consolidated from powder mixture, at a deformation temperature range of 600 °C–850 °C and strain rate of 0.1 s−1–10 s−1, was investigated through isothermal compression tests. The cracking behavior of the as-cast ingot metallurgy (IM) Ti-5553 alloy, at a deformation temperature of 700 °C was also investigated for comparison. Results suggested that the PM Ti-5553 alloy had a better hot workability, with a larger cracking-free processing window, and a lower deformation resistance than the IM counterpart. 45° shear fracture occurred in the PM alloy, compressed at the condition of 600 °C/10 s−1, and edge cracking was observed at the 700 °C/10 s−1. 45° shear fracture was also significant in the IM alloy specimen tested at 700 °C/10 s−1, and all the other IM alloy specimens compressed at 700 °C displayed longitudinal cracking. Moreover, the microscopic cracking observation showed that ductile dimple cracking can be found in the IM alloy, but brittle cleavage fracture was dominant in the cracking surface of PM alloy with a relatively low cracking ductility.

scholarly journals Hot Deformation Behavior and Workability of In-Situ TiB2/7050Al Composites Fabricated by Powder Metallurgy

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5319
Author(s):  
Haofei Zhu ◽  
Jun Liu ◽  
Yi Wu ◽  
Qing Zhang ◽  
Qiwei Shi ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Grain Boundary Sliding ◽  
Hot Workability ◽  
Compression Tests ◽  
Hollomon Parameter ◽  
Continuous Dynamic Recrystallization ◽  
Fine Grain ◽  
Grain Structures ◽  
Tib2 Particles

Isothermal compression tests of in-situ TiB2/7050Al composites fabricated by powder metallurgy were performed at 300–460 °C with the strain rate varying from 0.001 s−1 to 1 s−1. The Arrhenius constitutive equation and hot processing map of composites were established, presenting excellent hot workability with low activation energies and broad processing windows. Dramatic discontinuous/continuous dynamic recrystallization (DDRX/CDRX) and grain boundary sliding (GBS) take place in composites during deformation, depending on the Zener-Hollomon parameter (Z) values. It is found that initially uniform TiB2 particles and fine grain structures are beneficial to the DDRX, which is the major softening mechanism in composites at high Z values. With the Z value decreasing, dynamic recovery and CDRX around particles are enhanced, preventing the occurrence of DDRX. In addition, fine grain structures in composites are stable at elevated temperature thanks to the pinning of dense nanoparticles, which triggers the occurrence of GBS and ensures good workability at low Z values.

Thermal Deformation Behavior and Processing Map of Al-Mg-Er Alloy

2018 ◽  
Vol 913 ◽  
pp. 30-36
Author(s):  
Ran Liu ◽  
Hui Huang ◽  
Ya Liu ◽  
Li Rong
Keyword(s):  
Flow Stress ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Material Model ◽  
Instability Criterion ◽  
Strain Rates ◽  
Processing Maps ◽  
Hot Workability ◽  
Compression Tests ◽  
Dynamic Material Model

To study the hot deformation behavior of Al-Mg-Er alloy, hot compression tests were conducted on a Gleeble-1500D thermal simulator at the temperature range of 200-500°C with the strain rates from 0.001 to 10s-1. With the increase in the deformation temperature and the decrease in strain rates, the flow stress of the Al-Mg-Er alloy decreased. Processing maps were constructed to study on hot workability characteristics. The results showed that the flow stress curves exhibited the typical dynamic recrystallization characteristics and the stress decreased with the increase of deformation temperature and the decrease of strain rate. Moreover, the processing maps were established on the basis of dynamic material model and Prasad’s instability criterion.

scholarly journals Hot Workability of 300M Steel Investigated by In Situ and Ex Situ Compression Tests

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 880 ◽  
Author(s):  
Rongchuang Chen ◽  
Haifeng Xiao ◽  
Min Wang ◽  
Jianjun Li
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Working ◽  
Ex Situ ◽  
Lower Strain Rate ◽  
Hot Workability ◽  
Compression Tests ◽  
300M Steel ◽  
Lower Strain

In this work, hot compression experiments of 300M steel were performed at 900–1150 °C and 0.01–10 s−1. The relation of flow stress and microstructure evolution was analyzed. The intriguing finding was that at a lower strain rate (0.01 s−1), the flow stress curves were single-peaked, while at a higher strain rate (10 s−1), no peak occurred. Metallographic observation results revealed the phenomenon was because dynamic recrystallization was more complete at a lower strain rate. In situ compression tests were carried out to compare with the results by ex situ compression tests. Hot working maps representing the influences of strains, strain rates, and temperatures were established. It was found that the power dissipation coefficient was not only related to the recrystallized grain size but was also related to the volume fraction of recrystallized grains. The optimal hot working parameters were suggested. This work provides comprehensive understanding of the hot workability of 300M steel in thermal compression.

scholarly journals Dynamic Softening Mechanisms and Microstructure Evolution of TB18 Titanium Alloy during Uniaxial Hot Deformation

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 789
Author(s):  
Qiang Fu ◽  
Wuhua Yuan ◽  
Wei Xiang
Keyword(s):  
Titanium Alloy ◽  
Dynamic Recovery ◽  
True Strain ◽  
Hot Workability ◽  
Compression Tests ◽  
Phase Zone ◽  
Β Phase ◽  
Stability And Instability ◽  
Dynamic Softening ◽  
Transus Temperature

In this study, isothermal compression tests of TB18 titanium alloy were conducted using a Gleeble 3800 thermomechanical simulator for temperatures ranging from 650 to 880 °C and strain rates ranging from 0.001 to 10 s−1, with a constant height reduction of 60%, to investigate the dynamic softening mechanisms and hot workability of TB18 alloy. The results showed that the flow stress significantly decreased with an increasing deformation temperature and decreasing strain rate, which was affected by the competition between work hardening and dynamic softening. The hyperbolic sine Arrhenius-type constitutive equation was established, and the deformation activation energy was calculated to be 303.91 kJ·mol−1 in the (α + β) phase zone and 212.813 kJ·mol−1 in the β phase zone. The processing map constructed at a true strain of 0.9 exhibited stability and instability regions under the tested deformation conditions. The microstructure characteristics demonstrated that in the stability region, the dominant restoration and flow-softening mechanisms were the dynamic recovery of β phase and dynamic globularization of α grains below transus temperature, as well as the dynamic recovery and continuous dynamic recrystallization of β grains above transus temperature. In the instability region, the dynamic softening mechanism was flow localization in the form of a shear band and a deformation band caused by adiabatic heating.

Fracture Toughness of Powder Metallurgy and Ingot Titanium Alloys – A Review

2013 ◽  
Vol 551 ◽  
pp. 143-160 ◽  
Author(s):  
Ajit Pal Singh ◽  
Brian Gabbitas ◽  
De Liang Zhang
Keyword(s):  
Fracture Toughness ◽  
Powder Metallurgy ◽  
Titanium Alloys ◽  
Alloy Composition ◽  
Low Cost ◽  
Ingot Metallurgy ◽  
Metal Powders ◽  
Critical Factors ◽  
Microstructural Characteristics ◽  
High Degree

Powder metallurgy (PM) is potentially capable of producing homogeneous titanium alloys at relative low cost compared to ingot metallurgy (IM). There are many established PM methods for consolidating metal powders to near net shapes with a high degree of freedom in alloy composition and resulting microstructural characteristics. The mechanical properties of titanium and its alloys processed using a powder metallurgical route have been studied in great detail; one major concern is that ductility and toughness of materials produced by a PM route are often lower than those of corresponding IM materials. The aim of this paper is to review the fracture toughness of both PM and IM titanium alloys. The effects of critical factors such as interstitial impurities, microstructural features and heat treatment on fracture toughness are also discussed

Optimized hot workability of a powder metallurgy nickel-base superalloy

2019 ◽  
Vol 147 ◽  
pp. 340-352 ◽  
Author(s):  
Liming Tan ◽  
Yunping Li ◽  
Guoai He ◽  
Feng Liu ◽  
Yan Nie ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Nickel Base Superalloy ◽  
Hot Workability ◽  
Nickel Base ◽  
Base Superalloy

scholarly journals A novel experimental method to characterise the shear strength of concrete based on pre-stressed samples. A comparison with existing techniques

2018 ◽  
Vol 183 ◽  
pp. 02049
Author(s):  
Pascal Forquin ◽  
Reem Abdul-Rahman ◽  
Dominique Saletti
Keyword(s):  
Experimental Method ◽  
Shear Fracture ◽  
Plain Concrete ◽  
Concrete Specimen ◽  
Compression Tests ◽  
Second Stage ◽  
Wide Range ◽  
Metallic Ring ◽  
Do So ◽  
Metallic Cell

Mode II shear fracture process can be observed in plain-concrete structures exposed to intensive loadings such as shock, blasting or projectile-impact. It is the reason why the quasi-static and dynamic shear fracturing properties of concrete need to be investigated. In previous works performed by Forquin and coauthors a passive confining cell was applied to PTS (Punch-Through-Shear) specimens in a similar way than in quasi-oedometric compression tests where metallic ring are used as passive confinement. However the change of confining level during the sample loading constitutes a main drawback of this technique. In the present work a novel testing method is proposed based on a pre-stressing of the sample. To do so, the concrete specimen is inserted into pre-stressed metallic cell. During the unloading stage confining stresses are transferred to the ligament of the sample. In a second stage, a differential displacement applied to the central part of the sample toward the side parts produces a shearing of the ligament. The experiments performed in static and dynamic conditions (SHPB testing) allow the shear response of concrete to be determined over a wide range of strain-rates. In the present communication, the testing technique and obtained results are compared to the obtained data with the previous experimental method.

scholarly journals The Investigation on Flow Behavior of Powder Metallurgy Ti-10V-2Fe-3Al Alloy Using the Prasad Stability Criterion

2019 ◽  
Vol 50 (11) ◽  
pp. 5314-5323 ◽  
Author(s):  
Krystian Zyguła ◽  
Marek Wojtaszek ◽  
Oleksandr Lypchanskyi ◽  
Tomasz Śleboda ◽  
Grzegorz Korpała ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Power Dissipation ◽  
Hot Deformation ◽  
High Efficiency ◽  
Flow Instability ◽  
Flow Behavior ◽  
Material Model ◽  
Instability Criterion ◽  
Processing Maps ◽  
Compression Tests

Abstract The hot deformation behavior of Ti-10V-2Fe-3Al alloy obtained by the powder metallurgy (PM) method was investigated. Material for the research was produced by blending of elemental powders followed by uniaxial hot pressing. Thermomechanical tests of Ti-10V-2Fe-3Al compacts were carried out to determinate the stress-strain relationships at the temperature range of 800 °C to 1000 °C and strain rate between 0.01 and 10 s−1. Based on the dynamic material model (DMM) theory, processing maps at constant strain value were developed using data obtained from hot compression tests. The processing maps were elaborated for the final strain value, which was 0.9, and with flow instability criterion domains applied to it. Two critical regions associated with the flow behavior of the investigated material were revealed. Microstructural changes during hot deformation at various temperatures and strain rates were discussed. The correlation between calculated efficiency of power dissipation, flow instability criterion, and microstructure evolution was determined. The presence of defects was confirmed in regions predicted by the instability maps. The microstructure of the investigated alloy, corresponding to the high efficiency of power dissipation characterized by the occurrence of dynamic recrystallization (DRX) phenomena, was also shown. Additionally, average hardness values in relation to variable process parameters were designated. Based on the conducted studies and analysis, processing windows for Ti-10V-2Fe-3Al alloy compacts were proposed.

Hot Deformation and Dynamic Recrystallization in Titanium Aluminide

2018 ◽  
Vol 941 ◽  
pp. 1391-1396 ◽  
Author(s):  
Nitish Bibhanshu ◽  
Satyam Suwas
Keyword(s):  
Shear Band ◽  
Dynamic Recrystallization ◽  
Titanium Aluminide ◽  
Volume Fraction ◽  
Shear Bands ◽  
Hot Workability ◽  
Compression Tests ◽  
Electron Backscattered Diffraction ◽  
Gamma Titanium Aluminide ◽  
Z Contrast

The hot workability of gamma titanium aluminide alloy, Ti-48Al-2V-2Nb, was assessed in the cast condition through a series of compression tests conducted over a range of temperatures (1000 to 1175 °C) and at the strain rate of 10 S-1. The mechanism of dynamics recrystallization has been investigated from SEM Z-contrast images and from the Electron backscattered diffraction EBSD as well. It has been observed that volume fraction of the recrystallized grains increases with increasing the deformation temperature. The major volume fraction of the recrystallized grains was observed in the shear band which was forming at an angle 45 ̊ with respect to the compression direction. The mechanism of breaking of the laths and the region of the dynamic recrystallization were also investigated from the SEM Z-contrast image and EBSD. The dynamic recrystallization occurred in the region of the broken laths and shear bands. The breaking of the laths was because of the kinking of the lamellae. The shear band, kinked lamellae and dynamic recrystallized region where all investigated simultaneously.

scholarly journals Effect of Strain Rate on Hot Ductility of a Duplex Stainless Steel

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Zhenhua Wang ◽  
Wenyuan Ma ◽  
Chengming Wang
Keyword(s):  
Strain Rate ◽  
Hot Forging ◽  
Total Elongation ◽  
Strain Rate Range ◽  
Hot Ductility ◽  
Hot Workability ◽  
Crack Tips ◽  
The Difference ◽  
Edge Cracking ◽  
Reduction In Area

Duplex stainless steels (DSSs) often have bad hot workability. In this study, specimens of 2205 DSS were hot tensioned over a strain rate range from 0.005 s–1 to 50 s–1 to examine the hot ductility. The crack morphology was observed, and the dependence of hot ductility on the strain rate was analyzed. From 0.005 s–1 to 0.5 s–1, both the total elongation and the reduction in area increased with the strain rate. The reduction in area exhibited a small decrease when the strain rate was greater than 0.5 s–1. More than 85% of cracks formed between the ferrite and austenite, and no less than 70% of crack tips propagated between the ferrite and austenite. When the strain rate was increased from 0.005 s–1 to 0.5 s–1, dynamic recrystallization was promoted in the austenite, and the number fraction of low-angle grain boundaries in the ferrite was improved. The higher strain rate reduced the difference between ferrite and austenite in hardness, which improved the hot ductility. For 2205 DDS, the suggested strain rate is 0.5 s–1 and above to avoid surface and edge cracking during hot forging or hot rolling. The findings will be of value for the understanding of hot ductility of DSSs and other dual-phase alloys.

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