scholarly journals Enhanced Fatigue Strength of Commercially Pure Ti Processed by Rotary Swaging

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Hasan ALkhazraji ◽  
Ehab El-Danaf ◽  
Manfred Wollmann ◽  
Lothar Wagner
Keyword(s):  
Grain Size ◽  
Fatigue Strength ◽  
Crack Growth ◽  
Slip Length ◽  
Pure Titanium ◽  
Fatigue Tests ◽  
Recrystallization Temperature ◽  
Commercially Pure Titanium ◽  
Rotary Swaging ◽  
Commercially Pure

Fully reversed bending fatigue tests were performed on polished hour-glass specimens of commercially pure titanium grade 1 with three different grain sizes, that were produced by severe plastic deformation (rotary swaging) and subheat treatments, in order to examine the effect of grain size on fatigue. An improvement in fatigue strength was observed, as the polycrystal grain size was refined. The endurance limit stress was shown to depend on the inverse square root of the grain size as described empirically by a type of Hall-Petch relation. The effect of refining grain size on fatigue crack growth is to increase the number of microstructural barriers to the advancing crack and to reduce the slip length ahead of the crack tip, and thereby lower the crack growth rate. It was found that postdeformation annealing above recrystallization temperature could additionally enhance the work-hardening capability and the ductility of the swaged material, which led to a marked reduction in the fatigue notch sensitivity. At the same time, this reduction was accompanied with a pronounced loss in strength. The high cycle fatigue performance was discussed in detail based on microstructure and mechanical properties.

Monotonic and cyclic behavior of the nitrogen ion-implanted commercially pure-titanium

2021 ◽  
Vol 15 (1) ◽  
pp. 7662-7670
Author(s):  
N. Ali ◽  
M.S. Mustapa ◽  
T. Sujitno ◽  
T.E. Putra ◽  
Husaini .
Keyword(s):  
Material Properties ◽  
Room Temperature ◽  
Pure Titanium ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Cyclic Behavior ◽  
Strain Hardening Exponent ◽  
Commercially Pure Titanium ◽  
Commercially Pure ◽  
Nitrogen Ion

This research aims to study the behavior of monotonic and cyclic plastic deformation on commercially pure titanium which has undergone surface treatment using the nitrogen ion implantation method. The doses of 2.0×1017 ions/cm2 and the energy of 100 keV were used to implant the nitrogen ions into the CpTi. Monotonic properties tests were performed in a laboratory air and at room temperature using ASTM E8 standard specimens. Fatigue and corrosion fatigue tests were conducted in a laboratory  air and in artificial saline solutions, at room temperature using ASTM 1801-97 specimens. Tensile tests were carried out with constant displacement rate and fatigue tests were carried under fully-reversed with stress-controlled conditions with stress amplitudes 230, 240, 250, 260, 270 and 280 MPa. The results showed the material properties of monotonic behavior for CpTi and Nii-Ti; tensile strength (σu) of 497 and 539 MPa and for 0.2% offset yield strength (σy) of 385 and 440 MPa, respectively and of cyclic behavior; cyclic strength coefficient (k’) of 568.41 and 818.64 and cyclic strain hardening exponent (n’) of 0.176 and 0.215, respectively. This study has succeeded in producing useful new material properties that will contribute to the field of material science and engineering.

Processing by Hydrostatic Extrusion of Titanium Coated with Aluminides

2006 ◽  
Vol 114 ◽  
pp. 63-68 ◽  
Author(s):  
Halina Garbacz ◽  
Wacław Pachla ◽  
Tadeusz Wierzchoń ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Grain Size ◽  
Wear Resistance ◽  
Glow Discharge ◽  
Room Temperature ◽  
Pure Titanium ◽  
Hydrostatic Extrusion ◽  
Commercially Pure Titanium ◽  
Size Refinement ◽  
Frictional Wear ◽  
Commercially Pure

The material examined was commercially pure titanium with intermetallic Ti-Al layers produced by magnetron sputtering followed by glow discharge assisted treatment. This material was subjected to hydrostatic extrusion at room temperature. This resulted in substantial grain size refinement in the titanium accompanied by significant property improvement. The intermetallic Ti- Al layers reduced the pressure required during hydroextrusion and also increased the microhardness and frictional wear resistance of the material.

Effects of Rolling Reduction on Cold Forming Properties of Commercially Pure Titanium Sheet

2019 ◽  
Vol 960 ◽  
pp. 9-13
Author(s):  
Run Qi Zhang ◽  
Yi Qin Cai ◽  
Hao Xu Wang ◽  
Zhuang Li ◽  
Qi Zhou
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
Microstructural Analysis ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Titanium Sheet ◽  
Cold Forming ◽  
Grain Sizes ◽  
Commercially Pure ◽  
Accumulated Strain

Different cold rolling reductions were adopted for commercially pure titanium sheet. Cold forming properties were investigated by a microstructural analysis, Vickers microhardness and erichsen value measurements. The results have shown that Cold rolling resulted in refined alpha grains. Alpha grain size was refined further by greater cold reduction. Alpha grain sizes of the specimens of processing 1, 2 and 3 reached 30.90 μm, 26.48 μm and 20.58 μm, respectively. Cold forming properties were affected by different alpha grain sizes. The hardness and erichsen value reached the lowest and the highest values for the specimens in processing 1. The hardness increased and erichsen value decreased due to the finer alpha grain size for the specimen which was cold-rolled at a reduction of 50% in processing 2. Erichsen test results of the specimens of processing 3 had the lowest values due to the deformation of a reduction of 70%. Cold forming properties of the specimens of processing 3 were deteriorated, this is because deformation leads to the high dislocation density and the stored energy increases with accumulated strain after deformation.

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.

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.

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