OS2014 Plastic deformation behaviour of pure titanium sheet under linear biaxial loading with large strain

In order to determine the evolution features of deformation twins for TA2 commercial pure titanium (cp-TA2), the TA2 samples were bent under different bending angles in three-point bending tests via a universal testing machine. The electron backscatter diffraction (EBSD) technique was applied to identify the grain boundaries (GBs) and twin boundaries (TBs) in the bending areas. The results reveal that the type of deformation area would effect the evolution of different deformation twins. It is inferred that the state of stress would promote the multiplication of the same type of deformation twins.

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Microstructural Design of an AlMgSi Alloy via ECAP Processing: An Advanced SPD Manufacturing Technique for NC/UFG Materials

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1114.143 ◽

2015 ◽

Vol 1114 ◽

pp. 143-148

Author(s):

Nicolae Serban ◽

Doina Răducanu ◽

Vasile Danut Cojocaru ◽

Nicolae Ghiban

Keyword(s):

Plastic Deformation ◽

Severe Plastic Deformation ◽

Grain Refinement ◽

Shape Change ◽

Large Strain ◽

Metallographic Analysis ◽

Cross Sectional ◽

Ecap Processing ◽

Microstructural Design ◽

Almgsi Alloy

Severe plastic deformation (SPD) has received enormous interest over the last two decades as a method capable of producing fully dense and bulk ultra-fine grained (UFG) and nanocrystalline (NC) materials. Significant grain refinement obtained by SPD leads to improvement of mechanical, microstructural and physical properties. Compared to classical deformation processes, the big advantage of SPD manufacturing techniques, represented in particular by equal channel angular pressing (ECAP) is the lack of shape-change deformation and the consequent possibility to impart extremely large strain. In ECAP processing, the workpiece is pressed through a die in which two channels of equal cross-section intersect at an angle of ϕ and an additional angle of ψ define the arc of curvature at the outer point of intersection of the two channels. As a result of pressing, the sample theoretically deforms by simple shear and retains the same cross-sectional area to allow repeated pressings for several cycles. A commercial AlMgSi alloy was investigated in our study. The specimens were processed at room temperature for multiple passes, using three different ECAP dies. All samples (ECAP processed and as-received) were subjected to metallographic analysis and mechanical testing. Several correlations between the main processing parameters and the resulting microstructural aspect and mechanical features for the processed material were established. It was shown that severe plastic deformation by means of ECAP processing can be used in aluminum alloys microstructural design as an advanced tool for grain refinement in order to attain the desired microstructure and mechanical properties.

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Effect of Grain Size on Deformation Twinning Behavior of Ti6Al4V Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.830-831.337 ◽

2015 ◽

Vol 830-831 ◽

pp. 337-340

Author(s):

Ashish Kumar Saxena ◽

Manikanta Anupoju ◽

Asim Tewari ◽

Prita Pant

Keyword(s):

Plastic Deformation ◽

Grain Size ◽

Strain Rate ◽

Deformation Behavior ◽

Deformation Behaviour ◽

Air Cooling ◽

Specific Strength ◽

Aerospace Applications ◽

Β Phase ◽

Plastic Deformation Behavior

An understanding of the plastic deformation behavior of Ti6Al4V (Ti64) is of great interest because it is used in aerospace applications due to its high specific strength. In addition, Ti alloys have limited slip systems due to hexagonal crystal structure; hence twinning plays an important role in plastic deformation. The present work focuses upon the grain size effect on plastic deformation behaviour of Ti64. Various microstructures with different grain size were developed via annealing of Ti64 alloy in α-β phase regime (825°C and 850°C) for 4 hours followed by air cooling. The deformation behavior of these samples was investigated at various deformation temperature and strain rate conditions. Detailed microstructure studies showed that (i) smaller grains undergoes twinning only at low temperature and high strain rate, (ii) large grain samples undergo twinning at all temperatures & strain rates, though the extent of twinning varied.

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Effect of grain size on the ductile-brittle fracture behavior of commercially pure titanium sheet metals

Materials Science and Engineering A ◽

10.1016/j.msea.2021.141630 ◽

2021 ◽

pp. 141630

Author(s):

Lei Sun ◽

Zhutian Xu ◽

Linfa Peng ◽

Xinmin Lai

Keyword(s):

Grain Size ◽

Brittle Fracture ◽

Fracture Behavior ◽

Pure Titanium ◽

Commercially Pure Titanium ◽

Sheet Metals ◽

Titanium Sheet ◽

Commercially Pure

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Molecular Dynamics Modeling the Nano-Identation of Titanium

Volume 2: Manufacturing Processes; Manufacturing Systems; Nano/Micro/Meso Manufacturing; Quality and Reliability ◽

10.1115/msec2021-59982 ◽

2021 ◽

Author(s):

Peiqiang Yang ◽

Xueping Zhang ◽

Zhenqiang Yao ◽

Rajiv Shivpuri

Keyword(s):

Molecular Dynamics ◽

Plastic Deformation ◽

Titanium Alloys ◽

Large Scale ◽

Mechanical Response ◽

Pure Titanium ◽

Dynamics Modeling ◽

Dynamics Model ◽

Nano Indentation ◽

Molecular Dynamics Modeling

Abstract Titanium alloys’ excellent mechanical and physical properties make it the most popular material widely used in aerospace, medical, nuclear and other significant industries. The study of titanium alloys mainly focused on the macroscopic mechanical mechanism. However, very few researches addressed the nanostructure of titanium alloys and its mechanical response in Nano-machining due to the difficulty to perform and characterize nano-machining experiment. Compared with nano-machining, nano-indentation is easier to characterize the microscopic plasticity of titanium alloys. This research presents a nano-indentation molecular dynamics model in titanium to address its microstructure alteration, plastic deformation and other mechanical response at the atomistic scale. Based on the molecular dynamics model, a complete nano-indentation cycle, including the loading and unloading stages, is performed by applying Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The plastic deformation mechanism of nano-indentation of titanium with a rigid diamond ball tip was studied under different indentation velocities. At the same time, the influence of different environment temperatures on the nano-plastic deformation of titanium is analyzed under the condition of constant indentation velocity. The simulation results show that the Young’s modulus of pure titanium calculated based on nano-indentation is about 110GPa, which is very close to the experimental results. The results also show that the mechanical behavior of titanium can be divided into three stages: elastic stage, yield stage and plastic stage during the nano-indentation process. In addition, indentation speed has influence on phase transitions and nucleation of dislocations in the range of 0.1–1.0 Å/ps.

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