Dislocation Dynamics-Based Modeling and Simulations of Subsurface Damages Microstructure of Orthogonal Cutting of Titanium Alloy
نویسندگان
چکیده
In this work, a novel method is put forward to quantitatively simulate the subsurface damages microstructural alteration of titanium alloy components subjected to microscale cutting. A trans-scale numerical framework is conducted with the purpose of revealing the underlying influence mechanism of tool structure parameters on subsurface dislocation configurations using a dislocation dynamics-based model, which considers both dislocation structural transformation and grain refining. Results showed that the developed framework not only captured the essential features of workpiece microstructure, but also predicted the subsurface damages layer states and their modifications. A series of defects were found in the material subsurface during the orthogonal cutting of titanium alloy, such as edge and screw dislocations, junctions, parallel slip lines, intersection dislocation bands, vacancy defects, and refinement grains. Particularly, in the process of micro-cutting, the depth of subsurface damages layer increased significantly with cutting length at the beginning, and then remained unchanged in the stable removal phase. Moreover, smaller edge radius and larger rake angle can greatly weaken the squeezing action and heat diffusion effect between the tool tip and workpiece, which further prevents the formation of subsurface defects and enhances finished surface quality. In addition, although increasing tool clearance angle could drastically lighten the thickness of subsurface damages layer, it is noteworthy that its performance would be decreased significantly when the clearance angle was greater than or equal to 5◦. The micro-end-milling experiment was performed to validate the existing simulation results, and the results show very good agreement.
منابع مشابه
Modelling and Numerical Simulation of Cutting Stress in End Milling of Titanium Alloy using Carbide Coated Tool
Based on the cutting force theory, the cutting stress in end milling operation was predicted satisfactorily through simulation of using finite element method. The mechanistic force models were introduced in high accuracy force predictions for most applications. The material properties in the simulations were defined based on the cutting force theory, as a function of strain and strain rate wher...
متن کاملThe Effect of Nose Radius on Cutting Force and Temperature during Machining Titanium Alloy (Ti-6Al-4V)
This paper presents a study the effect of nose radius (Rz-mm) on cutting force components and temperatures during the machining simulation in an orthogonal cutting process for titanium alloy (Ti-6Al-4V). The cutting process was performed at various nose radiuses (Rz-mm) while the depth of cut (d-mm), feed rate (fmm/tooth) and cutting speed (vc-m/ min) were remained constant. The main cutting fo...
متن کاملFinite Element Simulations of Ti6Al4V Titanium Alloy Machining to Assess Material Model Parameters of the Johnson-Cook Constitutive Equation
The machining of titanium alloys poses several inherent difficulties owing to their unique mechanical properties and cutting characteristics. Finite element (FE) simulations have reduced the burden of extensive experimental trials in understanding the deformation behavior and optimize the cutting process. The FE code relies on the qualitative nature of inputs such as material flow stress model,...
متن کاملDislocation Density-based Grain Refinement Modeling of Orthogonal Cutting of Commercially Pure Titanium
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. I...
متن کاملMachinability evaluation of Titanium alloy in Laser Assisted Turning
The use of titanium and its alloys has increased in various industries recently, because of their superior properties of these alloys. Titanium alloys are generally classified as difficult to machine materials because of their thermo-mechanical properties such as high strength-to-weight ratio and low thermal conductivity. Laser Assisted Machining (LAM) improves the machinability of high strengt...
متن کامل