Microstructure Alteration in the High-Speed Machining of Titanium Alloy Involved With Tool Wear and Cryogenic Condition

2021 ◽  
Author(s):  
Xin Li ◽  
Xueping Zhang ◽  
Rajiv Shivpuri
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Titanium Alloy ◽  
Tool Wear ◽  
High Speed ◽  
Volume Fraction ◽  
High Speed Machining ◽  
Phase Volume ◽  
Machined Surface ◽  
Phase Volume Fraction

Abstract The microstructure alteration generated in the high-speed machining of titanium alloy has significant influence on the performance, quality and service life of production. The prediction of grain size or phase distribution based on physics mechanism or the regression of experimental data have been reported in the process of static or quasi-static state. However, it is still a challenge to predict the phase transformation and grain growth process in machining accurately and effectively since it has characteristics of high strain, strain rate and temperature. In this paper, a novel FEM-based model involving with the microstructure alteration was introduced and implemented to predict finial grain size or phase result in the high-speed machining of Ti-6Al-4V alloys especially at the machined surface. The phase transformation process was proposed and discussed by considering tool wear and cryogenic condition at machined surface, while the microstructure results were displayed on the chip in the previous works. Firstly, the phase volume fraction and grain size were modelled by experimental data. Then the simulation based on the self-consistent method (SCM) was used to output strain and temperature distribution. Thirdly, the phase volume fraction and grain size expressions were transmitted into subroutine programs and the microstructure alteration process under the different cutting conditions were showed in the FE results. The simulation results of temperature, phase fraction and strain were compared against previous simulation or experiment results in published papers revealing good agreement. The proposed model was further to investigate the influence of tool wear and cutting temperature on machined surface. The results indicated that the tool wear increased heat at the flank face significantly resulting to β phase increasing and grain growth at machined surface and the cryogenic condition would lower temperature gradient as well as stress gradient contributing to reduce roughness and residual stress.

The Influence of the Ferrite and Pearlite Grain Size on the S-N Fatigue Characteristics of Steel

2014 ◽  
Vol 224 ◽  
pp. 3-8 ◽  
Author(s):  
Sebastian Kamiński ◽  
Marcel Szymaniec ◽  
Tadeusz Łagoda
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Volume Fraction ◽  
Fatigue Properties ◽  
Phase Volume ◽  
Bending Tests ◽  
Phase Volume Fraction ◽  
Similar Chemical ◽  
Fatigue Characteristics ◽  
Ferrite Grain Size

In this work an investigation of internal structure influence on mechanical and fatigue properties of ferritic-pearlitic steels is shown. Ferrite grain size and phase volume fraction of three grades of structural steel with similar chemical composition, but different mechanical properties, were examined. Afterwards, samples of the materials were subjected to cyclic bending tests. The results and conclusions are presented in this paper

Numerical Simulation of Steady and Unsteady Compressible Multiphase Flows

2012 ◽  
Author(s):  
Huiying Li ◽  
Sergio A. Vasquez
Keyword(s):  
Experimental Data ◽  
Multiphase Flows ◽  
Volume Fraction ◽  
Numerical Approach ◽  
Absolute Pressure ◽  
Multiphase Model ◽  
Phase Volume ◽  
Phase Volume Fraction ◽  
Wide Range ◽  
Liquid Flows

The present work concerns the development of an advanced numerical approach to simulate steady and unsteady compressible multiphase flows in the CFD solver FLUENT. Compressible multiphase flows can be simulated under the framework of either the multiphase Mixture/VOF or the Eulerian multifluid model. The governing equations solved are the mixture (Mixture or VOF model) or phase (Eulerian multifluid model) momentum, energy, species transport equations and phase volume fraction equations. Turbulence effects are accounted for using a range of multiphase turbulence models. For the compressible multiphase model, it assumes that only one phase is a compressible gas/gaseous mixture with multiple species. In gas-liquid flows, all the liquid phases can be compressible /incompressible liquid, while in gas-solid flows the solid phase can be treated as a granular flow. To ensure numerical stability and obtain physical solutions, the absolute pressure is limited in a way to satisfy the constraints for both incompressible and compressible flows that may exist in different regions. The compressible effects are taken into account by adding extra terms related to sound speed and phase volume fractions in both the phase volume fraction and the pressure-correction equations. For flow conditions at inlets and exits, only pressure and mass-flow-rate boundaries are applicable. The mixture Mach numbers are defined and used to determine the subsonic or supersonic flows and thermal boundary conditions. The compressible multiphase model have been successfully used to simulate steady and unsteady, sub- and super-sonic compressible multiphase flows in a wide range of 2D and 3D multiphase systems. The examples presented in the paper include: (1). Gas-liquid separation in a vertical cylindrical container; (2). Transient pressure variations in compressible liquid and gas-liquid flows of water hammers; (3). Sub- and super-sonic gas-liquid two-phase flows in a nozzle; (4). Cavitating and ventilated super-cavitating flows; and (5). 3D gas-liquid flows in a three-stream injector. The solver robustness and convergence performance will be discussed. The solutions will be compared with available experimental data or numerical solutions. Emphasis will be focused on the solver performances on simulations of compressible multiphase flows. Overall, the results obtained from the present compressible multiphase model are in line with analytical/CFD solutions or available experimental data. The numerical approach is reasonably fast and robust, and suitable for practical compressible multiphase applications.

Microstructure-Property Relationships of Two Ti2AlNb-based Intermetallic Alloys: Ti-15Al-33Nb(at.%) and Ti-21Al-29Nb(at.%)

2004 ◽  
Vol 842 ◽  
Author(s):  
Christopher J. Cowen ◽  
Dingqiang Li ◽  
Carl J. Boehlert
Keyword(s):  
Grain Size ◽  
Creep Resistance ◽  
Volume Fraction ◽  
Ductile Failure ◽  
Phase Volume ◽  
Phase Volume Fraction ◽  
Al Content ◽  
Creep Stress ◽  
Heat Treated ◽  
Elongation To Failure

ABSTRACTTwo Ti2AlNb intermetallic orthorhombic (O) alloys, Ti-15Al-33Nb and Ti-21Al-29Nb(at.%), were subtransus processed into sheets, using pancake forging and hot-pack rolling, and evaluated in tension (25 and 650°C) and creep (650–710°C) and the properties and deformation behavior were related to microstructure. Some of the microstructural features evaluated were grain boundary character, grain size, phase volume fraction, and morphology. The alloy Al content was important to strength and elongation-to-failure (εf), where higher Al contents lead to greater tensile strengths and lower εf values and a corresponding brittle fracture response. However, the room temperature (RT) strengths of Ti-15Al-33Nb, which exhibited greater BCC phase volume fractions than Ti-21Al-29Nb and ductile failure (εf >2%), were always greater than 775 MPa. The creep stress exponents (n) and activation energies (Qapp) suggested that a transition in the dominant creep deformation mechanism exists and is dependent on stress and microstructure. Supertransus heat treatment, which increased the prior-BCC grain size and resulted in a lath-type O+BCC microstructure, resulted in reduced creep strains and strain rates. In fact, the supertransus heat-treated Ti-15Al-33Nb microstructures exhibited greater creep resistance than subtransus heat-treated Ti-21Al-29Nb microstructures. Combining the creep observations with the tensile response, the supertransus heat treated Ti-15Al-33Nb lath O+BCC microstructures exhibited the most attractive combination of tensile strength, εf values, and creep resistance.

Experiment Study of Tool Wear and Surface Integrity in High Speed Milling of a New Damage-Tolerant Titanium Alloy

2012 ◽  
Vol 723 ◽  
pp. 177-181 ◽  
Author(s):  
Qi Shi ◽  
Yin Fei Yang ◽  
Ning He ◽  
Liang Li ◽  
Wei Zhao
Keyword(s):  
Titanium Alloy ◽  
Tool Wear ◽  
Surface Integrity ◽  
High Speed ◽  
White Layer ◽  
Cutting Tools ◽  
Machined Surface ◽  
High Speed Milling ◽  
Metallurgical Structure ◽  
Damage Tolerant

TC4-DT is a new damage-tolerant titanium alloy. In the paper, a series of experiments on tool wear and surface integrity in high speed milling of the alloy were carried out. The tool lives of different tool materials were studied and the wear mechanism of cutting tools was also investigated. Then surface integrity, including surface roughness, microhardness and metallurgical structure was studied and analyzed in high speed milling at different tool wear status. Results showed that K10 is the most suitable cutting tool after considering a combination of factors. And good surface integrity could be obtained in high speed milling of TC4-DT under all cutting situations. In addition, even with acutely worn stages, there has been no so-called serious hardening layer (or white layer) according to the study of microhardness and metallurgical structure beneath the machined surface.

Experimental Study on the Milling of a High Strength Titanium Alloy

2004 ◽  
Vol 471-472 ◽  
pp. 731-735 ◽  
Author(s):  
Guo Sheng Geng ◽  
Jiu Hua Xu ◽  
Ying Fei Ge ◽  
Yu Can Fu
Keyword(s):  
Titanium Alloy ◽  
Tool Wear ◽  
Tool Life ◽  
High Speed ◽  
Design Method ◽  
Orthogonal Experiment ◽  
High Strength ◽  
Machined Surface ◽  
Heavy Load ◽  
Metallographic Examination

A series of experiments were carried out on normal and high speed milling of a high strength titanium alloy (TA15). TA15 is a close alpha titanium alloy strengthened by solid solution with Al and other component. It is often used to make large structural parts in airplane and welded parts subject to heavy load. The tool life of several typical types of cutter commonly used in the milling of titanium alloy was studied by the orthogonal experiment design method. After multi-element regression analysis, the empirical equation of the tool life was stablished. The milling force and temperature were measured under different cutting conditions and tool wear status. The knowledge is useful to further understand and analysis of the cutting mechanism, machining quality and tool wear. The study on the machined surface integrity includes the following content: surface roughness, metallographic examination, work hardening and residual stress.

scholarly journals Effect of α and β Phase Volume Fraction on Machining Characteristics of Titanium Alloy Ti6Al4V

2016 ◽  
Vol 6 ◽  
pp. 63-70 ◽  
Author(s):  
Sandip Patil ◽  
Swapnil Kekade ◽  
Kamlesh Phapale ◽  
Shital Jadhav ◽  
Amit Powar ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Volume Fraction ◽  
Phase Volume ◽  
Phase Volume Fraction ◽  
Β Phase ◽  
Titanium Alloy Ti6al4v ◽  
Machining Characteristics
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