Microstructural damage during high-speed milling of titanium alloys

Thomas, Meurig; Turner, Sam; Jackson, M.

doi:10.1016/j.scriptamat.2009.11.009

Cited by 53 publications

(26 citation statements)

References 10 publications

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“…Conversely, the maximum depth to which twinning occurs increases with cutting speed (Figure 7.). The SPD layer reduces from ~48 μm at 12 m.min -1 to ~19 μm at 160 m.min -1 , which is in line with observations typical for conventional surface integrity techniques [3], [4], [20] and finite element models [21]. The samples taken from 95°, 135° and 175° show an increase in propensity for deformation both through twinning and SPD.…”

Section: Figure 5 Raw and 15 Hz Fourier Transformed Filtered Signalssupporting

confidence: 84%

“…Traditionally machinability is assessed by chip formation, cutting force, tool life and surface condition, but with no detailed examination or quantification of the subsurface microstructure. The authors have recently shown in currently used commercial titanium alloys that conventional and emerging machining practices impart substantial subsurface microstructural damage, such as mechanical twinning [3], [4]. Surface and subsurface twins in structure critical components have the potential to reduce service life [5]- [8].…”

Section: Introductionmentioning

confidence: 99%

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Linking Machining Response of Titanium Billet to Upstream Thermomechanical Processing

Crawforth¹,

Jackson²,

Turner³

et al. 2016

Proceedings of the 13th World Conference on Titanium

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The texture of a typical titanium billet has evolved during the primary breakdown forging steps and acts as a 'finger print' of the forging process. This has a lasting legacy and can have a significant influence not only on the machining process but also the material's in-service performance. This paper reports the force feedback on machining tools during face turning of a titanium (Timetal® 54M) billet and how variation in feedback level appears directly linked to processing history. During cutting, higher forces are required in regions where the billet has received greater amounts of total strain during upstream forging stages. Furthermore, subsurface microstructural analysis of the machined surface has revealed how upstream processing, through the development of specific crystallographic texture components, has a direct impact on the level of subsurface damage caused by machining.

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Section: Figure 5 Raw and 15 Hz Fourier Transformed Filtered Signalssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Linking Machining Response of Titanium Billet to Upstream Thermomechanical Processing

Crawforth¹,

Jackson²,

Turner³

et al. 2016

Proceedings of the 13th World Conference on Titanium

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“…Climb milling was choose since it is the most suitable path for high strength material and able to reduce a rubbing condition in machining [12]. The tool rotates opposite the feed direction and produced a thick to thin chip where thin chip on exit able to reduce a shock load and built up edge breakage [13]. Apart of that, trochoidal promises an intermittent tool engagement that gives an irregular impact between tool and workpiece.…”

Section: Fig 3 the Workpiece Was Rigidly Mounted Onto The Dynamometementioning

confidence: 99%

Step Over (ae) Effect on Cutting Parameters when Trochoidal Pocket Milling of Titanium Alloy Ti-6Al-4V

Ramli¹,

Sharif²,

Said³

et al. 2019

IJEAT

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Titanium alloy is highly demanding in the aerospace industry due to its unique properties such are high strength-to-weight ratio and high thermal conductivity thus, made the material widely used in aerospace industries and excellent in its applications. However, those criteria’s become a crucial issue for machinists as titanium is categorized as difficult-to-machined material. High thermal conductivity caused shorten tool life because of the heat generated during machining was transferred directly to the cutting tool and leads to rapid tool wear. This experiment was conducted using 3 axis CNC Milling machine under wet cutting conditions. In order to identify the effect of step over, cutting speed and feed rate were fixed at constant values while step over (ae) values were varieties. The effect investigated were tool wear, wear mechanisms and tool failure modes. Tools experienced a longer tool life at low cutting speed of 60m/min, while chipping and notch wear appeared at high cutting speed 90m/min. The increasing of the step over value give less than 10% of the wear and reduced only 15% of machining time. With this, trochoidal milling proved that the step over give a minor contribution to wear while the dominant contribution was cutting speed followed by feed rate where the wear rate increased as the cutting speed increased.

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“…Based on the research of Thomas, dislocations multiplication and collision in alpha-titanium phase made up the elementary components of subsurface damaged layer in machining Ti-6Al-4V [11]. For simulating the equiaxedaxis alpha grains, polycrystalline Hexagonal-Close-Packed (HCP) structure is utilized in DDD simulation module.…”

Section: Model Descriptionmentioning

confidence: 99%

Theoretical model for subsurface microstructure prediction in micro-machining Ti-6Al-4V alloy – Experimental validation

Bai

Tong

et al. 2018

International Journal of Mechanical Sciences

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In this study, a new multiscale framework based on 2.5D discrete dislocation dynamics is proposed to predict the subsurface damaged layer evolution in micro-milling titanium alloy Ti-6Al-4V. This model takes into account the characteristics of component microstructure transformation and grain refinement by tracking the movement of matrix defects such as multiplication, slip, climb, cross-slip, junction and annihilation. Meanwhile, to understand the size dependence effect in micro-machining operation, a novel finite element orthogonal cutting model with dislocation density-based strain gradient constitutive equation is proposed and applied to reveal the farfield solution of driving stress of subsurface defect. The subsurface damaged layer characteristics including dislocation distribution and microstructure alteration of Ti-6Al-4V under various cutting conditions are studied with qualitative and quantitative assessment. The effects of processing parameters on subsurface features are analyzed. The obtained results have been compared with experimental findings utilizing the X-ray diffraction tests for validation purpose.

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Microstructural damage during high-speed milling of titanium alloys

Cited by 53 publications

References 10 publications

Linking Machining Response of Titanium Billet to Upstream Thermomechanical Processing

Linking Machining Response of Titanium Billet to Upstream Thermomechanical Processing

Step Over (ae) Effect on Cutting Parameters when Trochoidal Pocket Milling of Titanium Alloy Ti-6Al-4V

Theoretical model for subsurface microstructure prediction in micro-machining Ti-6Al-4V alloy – Experimental validation

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