On the Effect of Electron Beam Melted Ti6Al4V Part Orientations during Milling

Dabwan, Abdulmajeed; Anwar, Saqib; Al-Samhan, Ali M.; Nasr, Mustafa M.

doi:10.3390/met10091172

Cited by 10 publications

(10 citation statements)

References 53 publications

(75 reference statements)

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“…Since the plastic deformation is dependent on the uniformity of the underlying microstructure. Therefore, due to differences in the microstructure across different faces in the case of the as-fabricated EBM part [20], the variation could be seen in the machined surface hardness (Fig. 10b).…”

Section: Micro-hardnessmentioning

confidence: 99%

“…For example, with the same machining parameters, the EBM part exhibited different surface roughness for different faces of the EBM part [9,20]. It was emphasized in these studies that care must be taken to select the tool feed direction with respect to the EBM layers/part orientations to achieve good surface quality during nishing the EBM parts.…”

Section: Introductionmentioning

confidence: 99%

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On the influence of heat treatment in suppressing the layer orientation effect in finishing of electron beam melted Ti6Al4V

Dabwan

Anwar

Al-Samhan

et al. 2021

Int J Adv Manuf Technol

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Electron beam melting (EBM) is gaining more interest due to its near-net-shape production and ability to process di cult to manufacture materials, such as titanium alloys. However, due to the poor surface quality of the EBM parts, nishing operations, such as machining, are required. The main issue in the nishing of the EBM parts is their directional properties that lead to different surface roughness values for different part orientations for the same employed machining parameters. In this study, EBM Ti6Al4V parts were subjected to heat treatment to suppress the effect of the part/layers' orientations effect during the nish milling process. Three different heat treatments were employed to the as-fabricated EBM Ti6Al4V parts. The ne lamellar microstructure was set as a target from the heat treatment due to its overall superior mechanical properties and also, to keep a fair comparison in the machining of the asfabricated and heat-treated EBM Ti6Al4V parts. The results of the heat treatments showed that the EBM Ti6Al4V parts heated at 600°C for 3 hours and then air-cooled exhibited the same ne lamellar microstructure and microhardness as that of the as-fabricated EBM parts. The other two heat treatments including heating at 950°C and 800°C for 2 hours followed by air cooling were not able to maintain the ne lamellar structure due to the increase in the width of the alpha grains. The as-fabricated and heattreated EBM Ti6Al4V parts were subjected to the milling operation by considering the three possible parts/layers orientation with respect to the tool feed directions. The milling results showed that the asfabricated parts showed up to a 27% difference in surface roughness for different part orientations. In contrast, the heat-treated parts showed uniform surface roughness for the three part orientations with a variation of 8%. Similarly, considerable differences were observed in the surface integrity and the machined surface microhardness (18%) of the as-fabricated EBM parts as compared to the heat-treated parts) 2%). The heat-treated parts showed more uniform and superior surface morphology across all the part orientations. This is because of the more uniform microstructure, less porosity, higher consolidation of the EBM layers, and elimination of the columnar grains in the case of the heat-treated parts as compared to the EBM parts. This study revealed that in the case of the heat-treated EBM part the effect of part orientation with respect to milling tool feed direction was almost removed.

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Section: Micro-hardnessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the influence of heat treatment in suppressing the layer orientation effect in finishing of electron beam melted Ti6Al4V

Dabwan

Anwar

Al-Samhan

et al. 2021

Int J Adv Manuf Technol

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“…Higher cutting forces are generated when the tool feed is along Face-1 and lower cutting forces are generated when the tool is fed across Face-2. It should be noted that cutting forces also affect the surface roughness as reported by [ 44 , 64 ]. Therefore, due to cutting forces and cutting speed changing simultaneously along with complicated distribution of the porosity in the L-PBF parts, no fixed trends are observed for Sa in Figure 6 .…”

Section: Resultsmentioning

confidence: 90%

“…However, no previous work has focused on achieving the L-PBF 316L SS parts surface quality by using a machining process with an emphasis on the L-PBF parts orientations with regard to the tool feed direction (TFD). Other studies have been reported on the milling of electron beam melted (EBM) γ-TiAl and Ti6Al4V parts by [ 43 , 44 ]. They reported that the different EBM part orientations during machining can generate various surface roughness even with the same machining parameters.…”

Section: Introductionmentioning

confidence: 99%

Investigations on the Effect of Layers’ Thickness and Orientations in the Machining of Additively Manufactured Stainless Steel 316L

et al. 2021

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Laser-powder bed fusion (L-PBF) process is a family of modern technologies, in which functional, complex (3D) parts are formed by selectively melting the metallic powders layer-by-layer based on fusion. The machining of L-PBF parts for improving their quality is a difficult task. This is because different component orientations (L-PBF-layer orientations) produce different quality of machined surface even though the same cutting parameters are applied. In this paper, stainless steel grade SS 316L parts from L-PBF were subjected to the finishing (milling) process to study the effect of part orientations. Furthermore, an attempt is made to suppress the part orientation effect by changing the layer thickness (LT) of the parts during the L-PBF process. L-PBF parts were fabricated with four different layer thicknesses of 30, 60, 80 and 100 μm to see the effect of the LT on the finish milling process. The results showed that the layer thickness of 60 μm has significantly suppressed the part orientation effect as compared to the other three-layer thicknesses of 30, 80 and 100 μm. The milling results showed that the three-layer thickness including 30, 80 and 100 μm presented up to a 34% difference in surface roughness among different part orientations while using the same milling parameters. In contrast, the layer thickness of 60 μm showed uniform surface roughness for the three-part orientations having a variation of 5–17%. Similarly, the three-layer thicknesses 30, 80 and 100 μm showed up to a 25%, 34% and 56% difference of axial force (Fa), feed force (Ff) and radial force (Fr), respectively. On the other hand, the part produced with layer thickness 60 μm showed up to 11%, 25% and 28% difference in cutting force components Fa, Ff and Fr, respectively. The three-layer thicknesses 30, 80 and 100 μm in micro-hardness were found to vary by up to 14.7% for the three-part orientation. Negligible micro-hardness differences of 1.7% were revealed by the parts with LT 60 μm across different part orientations as compared to 6.5–14% variations for the parts with layer thickness of 30, 80 and 100 μm. Moreover, the parts with LT 60 μm showed uniform and superior surface morphology and reduced edge chipping across all the part orientations. This study revealed that the effect of part orientation during milling becomes minimum and improved machined surface integrity is achieved if the L-PBF parts are fabricated with a layer thickness of 60 μm.

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“…The results showed that the cutting radial width, cutting speed, and axial cutting depth have obvious influences on the dry grinding of the Ti-6Al-4V alloy, and the mechanism for improving the performance of the microstructure tool is mainly its self-lubrication. Dabwan et al [ 20 ] studied the effects of the feed speed, radial cutting depth, and cutting speed on the surface roughness, cutting force, microhardness, microstructure, chip morphology, and surface morphology of Ti6Al4V. It was found that different orientations have different effects on the machined surface.…”

Section: Introductionmentioning

confidence: 99%

A Ti-6Al-4V Milling Force Prediction Model Based on the Taylor Factor Model and Microstructure Evolution of the Milling Surface

et al. 2022

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In this paper, a milling force prediction model considering the Taylor factor is established, and the Ti-6Al-4V milling force predicted by the model under different milling parameters is presented. In the study, the milling experiment of Ti-6Al-4V was carried out, the milling force was collected by the dynamometer, and the microstructure evolution of the milling surface before and after milling was observed by EBSD. Through the comparative analysis of the experimental results and the model prediction results, the reliability of the prediction model proposed in this study was verified, and the influences of the milling parameters on the milling force were further analyzed. Finally, based on the EBSD observation results, the effects of the milling parameters on the microstructure evolution of the milling surface were studied. The results show that both the tangential milling force and normal milling force increase with the increase in the milling depth and feed rate. Among the milling parameters selected in this study, the milling depth has the greatest influence on the milling force. The average errors of the tangential milling force and normal milling force predicted by the milling force model are less than 10%, indicating that the milling force prediction model established in this paper considering Taylor factor is suitable for the prediction of the Ti-6Al-4V milling force. With the change in the milling parameters, the grain structure, grain size, grain boundary distribution, phase distribution, and micro-texture of the material surface change to varying degrees, and the plastic deformation of the milling surface is largely coordinated by the slip.

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On the Effect of Electron Beam Melted Ti6Al4V Part Orientations during Milling

Cited by 10 publications

References 53 publications

On the influence of heat treatment in suppressing the layer orientation effect in finishing of electron beam melted Ti6Al4V

On the influence of heat treatment in suppressing the layer orientation effect in finishing of electron beam melted Ti6Al4V

Investigations on the Effect of Layers’ Thickness and Orientations in the Machining of Additively Manufactured Stainless Steel 316L

A Ti-6Al-4V Milling Force Prediction Model Based on the Taylor Factor Model and Microstructure Evolution of the Milling Surface

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