scholarly journals Study on Grinding and Deformation Fracture Control of Cold Rolled Titanium Strip

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 323 ◽  
Author(s):  
Jiaming Zhang ◽  
Wei Yu ◽  
Entao Dong ◽  
Zeyu Zhang ◽  
Jiaxin Shi ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Cold Rolling ◽  
Surface Defects ◽  
True Strain ◽  
Rolling Direction ◽  
Pure Titanium ◽  
Stress And Strain ◽  
Commercially Pure Titanium ◽  
Maximum Tensile Strain ◽  
Rolling Deformation

Surface defects of titanium strip need to be removed by local grinding, but local cracking or band breaking then occurs during subsequent cold rolling. Tensile properties and deformation resistance of 3 mm thick commercially pure titanium strip with grinding pits on the surface were simulated by a finite-element method using a multi-pass cold-rolling deformation process. The stress and strain of grinding pits with depths of 0.25–2 mm were analyzed. During cold-rolling deformation, the stress and strain in the center of a grinding pit were larger than at the edge region. The strip was first subjected to tensile stress in the rolling direction, which then decreased and gradually changed to compressive stress. Partial stress was larger in the rolling direction than in the transverse direction. When the tensile stress and true strain both exceeded the stress and strain limits during second-pass rolling, the strip with a grinding depth of 2 mm cracked, but shallower grinding pits were repaired. The criterion for cracking during rolling after grinding is that the maximum tensile strain at the bottom of the pit must be less than the critical strain of the material: ln ( 1 + h / H ) ≤ ε C r . Results of numerical simulation were verified by the data for cold-rolling tests.

scholarly journals Impact of rolling conditions on the hydriding of grade 2 titanium welded tubes

2020 ◽  
Vol 321 ◽  
pp. 09005
Author(s):  
La Chance LEPEMANGOYE ◽  
Nicolas CRETON ◽  
Virgil OPTASANU ◽  
Elise DELOYE ◽  
Tony MONTESIN ◽  
...  
Keyword(s):  
Cold Rolling ◽  
Crystallographic Texture ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Asymmetrical Rolling ◽  
Commercially Pure ◽  
Pole Figures ◽  
Cold Rolled ◽  
Titanium Grade ◽  
The Impact

In this article, we study the impact of rolling conditions on the texture of the commercially pure titanium grade 2. In a previous work, NEOTISS in collaboration with ICB laboratory, shown that the texture highly influences the precipitation of hydrides in Titanium. In order to create different textures, Titanium sheets grade 2 are cold rolled asymmetrically and symmetrically with or without lubricant. The inverse pole figures and direct pole figures obtained allow us to deduce that symmetrical cold rolling does not change the grains orientation but generates a rotation of grains along c-axis (normal to basal plan). However, asymmetrical cold rolling leads to the formation of a new crystallographic texture, which could limit the formation of the hydrides in titanium grade 2 submitted to a hydrogen-rich environment. Key words: asymmetrical rolling, symmetrical rolling, titanium, hydriding, texture

scholarly journals Impact of machining-induced surface defects on the edge formability of commercially pure titanium sheet at room temperature

2020 ◽  
Vol 2 (12) ◽  
Author(s):  
J. S. Kwame ◽  
E. Yakushina ◽  
P. Blackwell
Keyword(s):  
Room Temperature ◽  
Surface Defects ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Hole Expansion ◽  
Expansion Test ◽  
Hole Expansion Test ◽  
Edge Surface ◽  
Cp Ti ◽  
The Impact

AbstractDespite the good properties of titanium, which have drawn the interest of various industries over the years, one of the major drawbacks of this material is its poor machinability. This has largely been attributed to its low thermal conductivity and elastic modulus. The ability to attain the optimum sheet edge performance during forming is dependent on the quality of the edges produced. Also, the demanding nature of aerospace part design has provoked the interest of both industry and academia to continually explore avenues tailored at enhancing part performance. The sort of edge surface integrity produced for aerospace part fabrication thus becomes a vital consideration in the quest to ensuring prime performance of components. This work seeks to study the influence of different machining-induced surface defects on the sheet edge performance of CP-Ti (grade 2) at room temperature. Hole expansion test was used to assess the edge surface formability of CP-Ti with different machining-induced edge defects. The research found that machining-induced surface defects act as stress concentration sites during the hole expansion test and have a major impact on the material flow. Electro-discharge machined edges were observed to exhibit high edge formability compared to laser and abrasive water jet cut edges due to the impact of machining-induced microstructural changes.

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 Lubricant Influence on the Ejection and Roughness of In-Die Electro Sinter Forged Ti-Discs

2018 ◽  
Vol 767 ◽  
pp. 171-178 ◽  
Author(s):  
Emanuele Cannella ◽  
Chris Valentin Nielsen
Keyword(s):  
Surface Defects ◽  
Pure Titanium ◽  
Roughness Parameter ◽  
Axial Loading ◽  
Electrical Current ◽  
Radial Pressure ◽  
Sintered Sample ◽  
Commercially Pure Titanium ◽  
Mechanical Pressure ◽  
Sinter Forging

Electro Sinter Forging (ESF) is a new sintering process based on Joule heating by high electrical current flowing through compacted metal powder under mechanical pressure. The whole process takes about three seconds and is based on a closed-die setup, where the sample is sintered inside a die. A near-net shape component is therefore manufactured. One of the challenges associated with this process is the ejection of the sample after sintering. Due to powder compaction and axial loading during sintering, a radial pressure is generated at the die/sample interface. Consequently, the ejection can be difficult, and the final quality of the sintered component in terms of roughness and surface defects may be affected. In the present work, four different lubricants and non-lubricated conditions were tested to investigate the effects on the final part quality. The sintered sample is a disc made of commercially pure titanium powder. The force was measured while ejecting the samples by using a speed-controlled press. The surface roughness parameter Sa was measured by using a laser confocal microscope.

Effect of Planar Anisotropy and Tension-Compression Asymmetry of CP-Ti on its Deep Drawing Behavior at Room Temperature

2018 ◽  
Vol 913 ◽  
pp. 190-195
Author(s):  
Yong Gang Hao ◽  
Peng Lin ◽  
Bao You Zhang ◽  
Xiao Lei Cui ◽  
Chang Jiang Zhang ◽  
...  
Keyword(s):  
Deep Drawing ◽  
Room Temperature ◽  
Rolling Direction ◽  
Pure Titanium ◽  
Uniaxial Tensile ◽  
Commercially Pure Titanium ◽  
Planar Anisotropy ◽  
Tension And Compression ◽  
Cp Ti ◽  
Tension Compression Asymmetry

The planar anisotropy (PA) and tension-compression asymmetry (TCA) of the commercially pure titanium (CP-Ti) were investigated through uniaxial tension and compression experiments at room temperature. By deep drawing experiment, the formability and the earing profile for the CP-Ti were studied at room temperature. The deep drawing simulations using the hardening rules of uniaxial tensile or compression curves were compared with experimental results. The results show that the CP-Ti has obvious PA, and the plastic strain ratiosr0,r45andr90are 1.47, 1.64 and 2.05, respectively. The CP-Ti sheet shows the tension-compression asymmetry of yielding and hardening. The TCA also shows obvious PA. The tension-compression yield strength ratio of 0°, 45° and 90° to the rolling direction are 1.12, 1.08, 1.04, and the tension-compression hardening exponent ratio are 0.86, 0.8 and 0.62, respectively. The simulative results without considering TCA indicate that the forming force, the wall thickness and earing profile are not in good agreement with the experimental ones. Therefore, the earing appeared in 45° is contribution of the PA and TCA. The TCA will reduce the thickness of the deep drawing parts, increase the earing ratio and affect the drawing force.

Dynamic Recrystallization Behavior of Pure Titanium

2014 ◽  
Vol 852 ◽  
pp. 66-70 ◽  
Author(s):  
Juan Hua Su ◽  
Ya Wei Han ◽  
Feng Zhang Ren ◽  
Zhi Qiang Chen
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
True Strain ◽  
Pure Titanium ◽  
Avrami Equation ◽  
Test Machine ◽  
Commercially Pure Titanium ◽  
Compression Tests ◽  
Commercially Pure

The dynamic recrystallization of commercially pure titanium was investigated by compression tests on Gleeble-1500D thermal simulation test machine at temperature of 700950 °C and strain rate of 0. 015 s1. The total compression deformation is 0.7(true strain). The kinetics of dynamic recrystallization of commercially pure titanium at 950 °C was modeled by Avrami equation. The results show that the dynamic recovery and recrystallization obviously occur during compression. The flow stress increases to a peak value and gradually decreases to a steady state. The flow stress is decreased with the increase of deformation temperature and it is increased with the increase of strain rate. The Avrami kinetics model of dynamic recrystallization of commercially pure titanium at 950 °C is obtained .

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