scholarly journals Dislocation Density-Based Grain Refinement Modeling of Orthogonal Cutting of Commercially Pure Titanium

2011 ◽  
Author(s):  
Hongtao Ding ◽  
Yung C. Shin
Keyword(s):  
Grain Size ◽  
Finite Element ◽  
Dislocation Density ◽  
Mechanical Behavior ◽  
Grain Refinement ◽  
Orthogonal Cutting ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Commercially Pure ◽  
Cp Ti

Recently, machining has been exploited as a means for producing ultra-fine grained (UFG) and nanocrystalline microstructures for various metal materials, such as aluminum alloys, copper, stainless steel, titanium and nickel-based super alloys, etc. However, no predictive, analytical or numerical work has ever been presented to quantitatively predict the change of grain sizes during machining. In this paper, a dislocation density-based viscoplastic model is adapted for modeling the grain size refinement mechanism during machining by means of a finite element based numerical framework. A novel Coupled Eulerian-Lagrangian (CEL) finite element model embedded with the dislocation density subroutine is developed to model the severe plastic deformation and grain refinement during a steady-state cutting process. The orthogonal cutting tests of a commercially pure titanium (CP Ti) material are simulated in order to assess the validity of the numerical solution through comparison with experiments. The dislocation density-based material model is calibrated to reproduce the observed material constitutive mechanical behavior of CP Ti under various strains, strain rates and temperatures in the cutting process. It is shown that the developed model captures the essential features of the material mechanical behavior and predicts a grain size of 100–160 nm in the chips of CP Ti at a cutting speed of 10 mm/s.

Dislocation Density-Based Grain Refinement Modeling of Orthogonal Cutting of Titanium

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Hongtao Ding ◽  
Yung C. Shin
Keyword(s):  
Grain Size ◽  
Finite Element ◽  
Dislocation Density ◽  
Mechanical Behavior ◽  
Grain Refinement ◽  
Orthogonal Cutting ◽  
Cutting Process ◽  
Plasticity Model ◽  
Numerical Work ◽  
Cp Ti

Recently, orthogonal cutting has been exploited as a means for producing ultrafine grained (UFG) and nanocrystalline microstructures for various metal materials, such as aluminum alloys, copper, stainless steel, titanium and nickel-based super alloys, etc. However, no predictive, analytical or numerical work has ever been presented to quantitatively predict the change of grain sizes during plane-strain orthogonal cutting. In this paper, a dislocation density-based material plasticity model is adapted for modeling the grain size refinement mechanism during orthogonal cutting by means of a finite element based numerical framework. A coupled Eulerian–Lagrangian (CEL) finite element model embedded with the dislocation density subroutine is developed to model the severe plastic deformation and grain refinement during a steady-state cutting process. The orthogonal cutting tests of a commercially pure titanium (CP Ti) material are simulated in order to assess the validity of the numerical solution through comparison with experiments. The dislocation density-based material plasticity model is calibrated to reproduce the observed material constitutive mechanical behavior of CP Ti under various strains, strain rates, and temperatures in the cutting process. It is shown that the developed model captures the essential features of the material mechanical behavior and predicts a grain size of 100–160 nm in the chips of CP Ti at a cutting speed of 10 mm/s.

Numerical Investigation of Dislocation Density and Grain Size Evolution in Orthogonal Cutting of Pure Titanium Using Microgrooved Cutting Tools

2018 ◽  
Author(s):  
Han Wu ◽  
J. Ma ◽  
Shuting Lei
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Orthogonal Cutting ◽  
Cutting Tools ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Machined Surface ◽  
Fem Model ◽  
Commercially Pure ◽  
Cp Ti

In this paper, a coupled Eulerian-Lagrangian (CEL) finite element model is developed based on FEM software package Abaqus to solve the evolution of the dislocation density and grain size simultaneously. This validated CEL FEM model is then utilized to investigate the effects of microgrooved cutting tools on the evolution of dislocation density and grain size in orthogonal cutting of commercially pure titanium (CP Ti). Microgrooved cutting tools are cemented carbide (WC/Co) cutting inserts with microgrooves on the rake face. The effects of microgroove width and microgroove convex width are investigated in terms of cutting force, chip morphology, dislocation density, and grain size. It is concluded that this CEL FEM model can capture the essential features of orthogonal cutting of commercially pure titanium (CP Ti) alloy using microgrooved cutting tools. It is also concluded that microgroove width and convex width have substantial influence on the dislocation density profiles and grain size profiles along the depth from the machined surface and the tool-chip interface, respectively. This conclusion provides insightful guidance for altering the surface integrity of the machined surface based on needs.

scholarly journals Changes of Microstructures and Mechanical Properties in Commercially Pure Titanium after Different Cycles of Proposed Multi-Directional Forging

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 175 ◽  
Author(s):  
Zhanguang Zheng ◽  
Xiaoying Zhang ◽  
Liang Xie ◽  
Longgui Huang ◽  
Teng Sun
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Mechanical Test ◽  
Size Fraction ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Commercially Pure ◽  
Refinement Mechanism ◽  
Dislocations Density ◽  
Cp Ti

A newly proposed multi-directional forging (MDF) was successfully applied to a commercially pure titanium (CP Ti). Severe plastic deformation would result in significant and complex changes of microstructure and mechanical properties, so microstructure characterization and a mechanical test of CP Ti were conducted after different cycles of MDF. The results demonstrated that dynamic recrystallization was the dominant grain refinement mechanism of MDF CP Ti. With increasing the cycles of MDF, grain size, fraction of low angle grain boundaries and dislocations density decreased due to grain refined. After three cycles of MDF, the mean grain size was about 200 nm. The values of tensile strength and hardness increased significantly from zero cycles to one cycle of MDF, but increased slowly after one MDF cycle. Numerous dimples and tear ridges were present, but the dimples were smaller and shallower with increasing cycles of MDF.

Computation on continuous grain refinement in AA1050 aluminum during repetitive tube expansion and shrinking technique

2015 ◽  
Vol 232 (4) ◽  
pp. 307-318
Author(s):  
H Jafarzadeh ◽  
K Abrinia
Keyword(s):  
Finite Element Method ◽  
Plastic Deformation ◽  
Grain Size ◽  
Finite Element ◽  
Dislocation Density ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Half Cycle ◽  
Tube Expansion ◽  
Element Method

The microstructure evolution during recently developed severe plastic deformation method named repetitive tube expansion and shrinking of commercially pure AA1050 aluminum tubes has been studied in this paper. The behavior of the material under repetitive tube expansion and shrinking including grain size and dislocation density was simulated using the finite element method. The continuous dynamic recrystallization of AA1050 during severe plastic deformation was considered as the main grain refinement mechanism in micromechanical constitutive model. Also, the flow stress of material in macroscopic scale is related to microstructure quantities. This is in contrast to the previous approaches in finite element method simulations of severe plastic deformation methods where the microstructure parameters such as grain size were not considered at all. The grain size and dislocation density data were obtained during the simulation of the first and second half-cycles of repetitive tube expansion and shrinking, and good agreement with experimental data was observed. The finite element method simulated grain refinement behavior is consistent with the experimentally obtained results, where the rapid decrease of the grain size occurred during the first half-cycle and slowed down from the second half-cycle onwards. Calculations indicated a uniform distribution of grain size and dislocation density along the tube length but a non-uniform distribution along the tube thickness. The distribution characteristics of grain size, dislocation density, hardness, and effective plastic strain were consistent with each other.

Thermomechanical Response of Commercially Pure Titanium under Large Plastic Deformation at High Strain Rates

2012 ◽  
Vol 548 ◽  
pp. 174-178 ◽  
Author(s):  
Chong Yang Gao ◽  
Wei Ran Lu
Keyword(s):  
Pure Titanium ◽  
Optimal Solution ◽  
Optimization Method ◽  
Strain Rates ◽  
Commercially Pure Titanium ◽  
Thermomechanical Response ◽  
Commercially Pure ◽  
Different Temperatures ◽  
Cp Ti ◽  
Constitutive Parameters

By using a dislocation-based plastic constitutive model for hcp metals developed by us recently, the dynamic thermomechanical response of an important industrial material, commercially pure titanium (CP-Ti), was described at different temperatures and strain rates. The constitutive parameters of the material are determined by an efficient optimization method for a globally optimal solution. The model can well predict the dynamic response of CP-Ti by the comparison with experimental data and the Nemat-Nasser-Guo model.

The Influence of Laser Irradiation Parameters on Tribological Behaviour of Commercially Pure Titanium for Dental Prostheses

2016 ◽  
Author(s):  
Karibeeran Shanmuga Sundaram ◽  
Gurusami Kiliyappan ◽  
Senthil Kumaran Selvadurai
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Pure Titanium ◽  
Laser Surface ◽  
Commercially Pure Titanium ◽  
Laser Shock ◽  
Micro Hardness ◽  
Dental Prostheses ◽  
Commercially Pure ◽  
Cp Ti

Laser shock peening (LSP) is one of the innovative technique that produces a compressive residual stress on the surface of metallic materials, thereby significantly increasing its fatigue life in applications where failure is caused by surface-initiated cracks. The specimens were treated with laser shock waves with different processing parameters, and characterization studies were made on treated specimens. The purpose of the present study was to investigate the influence of Nd:YAG laser on commercially pure titanium (CP-Ti) used in prosthetic dental restorations. The treatment influenced change in microstructure, micro hardness, surface roughness, and wear resistance characteristics. Though CP-Ti is considered as an excellent material for dental applications due to its outstanding biocompatibility, it is not suitable when high mastication forces are applied. In the present study, pulsed Nd:YAG laser surface treatment technique was adopted to improve the wear resistance of CP-Ti. The wear test pin specimens of CP-Ti were investment cast with centrifugal titanium casting machine. The wear properties of specimens were evaluated after LSP on a “pin-on-disc” wear testing tribometer, as per ASTM G99-05 standards. The results of the wear experiment showed that the treated laser surface has higher wear resistance, micro hardness, and surface roughness compared to as-cast samples. The improvement of wear resistance may be attributed due to grain refinement imparted by LSP processes. The microstructure, wear surfaces, wear debris, and morphology of the specimen were analyzed by using optical electron microscope, scanning electron microscope, and X-ray diffraction (XRD). The data were compared using ANOVA and post-hoc Tukey tests. The characteristic change resulted in increase in wear resistance and decrease in wear rate. Hence, it is evident that the more reliable and removable partial denture metal frameworks for dental prostheses may find its applications.

scholarly journals The influence of mold temperature on the fit of cast crowns with commercially pure titanium

2005 ◽  
Vol 19 (2) ◽  
pp. 139-143 ◽  
Author(s):  
Wagner Sotero Fragoso ◽  
Guilherme Elias Pessanha Henriques ◽  
Edwin Fernando Ruiz Contreras ◽  
Marcelo Ferraz Mesquita
Keyword(s):  
Pure Titanium ◽  
Mold Temperature ◽  
Commercially Pure Titanium ◽  
Mechanical Grinding ◽  
Marginal Fit ◽  
Commercially Pure ◽  
Cp Ti

Commercially pure titanium (CP Ti) has been widely applied to fabricate cast devices because of its favorable properties. However, the mold temperature recommended for the manufacture of casts has been considered relatively low, causing inadequate castability and poor marginal fit of cast crowns. This study evaluated and compared the influence of mold temperature (430°C - as control, 550°C, 670°C) on the marginal discrepancies of cast CP Ti crowns. Eight bovine teeth were prepared on a mechanical grinding device and impressions were used to duplicate each tooth and produce eight master dies. Twenty-four crowns were fabricated using CP Ti in three different groups of mold temperature (n = 8): 430°C (as control), 550°C and 670°C. The gap between the crown and the bovine tooth was measured at 50 X magnification with a traveling microscope. The marginal fit values of the cast CP Ti crowns were submitted to the Kruskal-Wallis test (p = 0.03). The 550°C group (95.0 µm) showed significantly better marginal fit than the crowns of the 430°C group (203.4 µm) and 670°C group (213.8 µm). Better marginal fit for cast CP Ti crowns was observed with the mold temperature of 550°C, differing from the 430°C recommended by the manufacturer.

Pack Cementation Treatment of Titanium Using Tetracalcium Phosphate Powder for Biomedical Applications

2010 ◽  
Vol 654-656 ◽  
pp. 2172-2175
Author(s):  
Kyosuke Ueda ◽  
Hajime Suto ◽  
Kaori Nakaie ◽  
Takayuki Narushima
Keyword(s):  
Reaction Layer ◽  
Biomedical Applications ◽  
Pure Titanium ◽  
Pack Cementation ◽  
Apatite Formation ◽  
Commercially Pure Titanium ◽  
Tetracalcium Phosphate ◽  
Phosphate Powder ◽  
Commercially Pure ◽  
Cp Ti

The surface modification of commercially pure titanium (CP Ti) by pack cementation treatment at 973 K using tetracalcium phosphate (Ca4(PO4)2O, TTCP) slurry was investigated. An HAp phase and a CaTiO3 phase were observed on the reaction layer of the CP Ti substrate after pack cementation treatment at 973 K for 86.4 ks. TTCP powder decomposed to HAp and CaO, and CaO reacted with TiO2 to form CaTiO3. The reaction layer on the CP Ti substrate consisted of inner and outer layers and the particles were in the outer reaction layer. The pores observed on the reaction layer were formed by the detachment of particles from the outer layer. The bonding strength of the reaction layer was 68.1 MPa. Apatite completely covered the surface of the pack-cementation-treated CP Ti after immersion in Kokubo solution for 21.6 ks; such rapid apatite formation suggests that pack cementation treatment improves the biocompatibility of titanium.

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