The influence of laser assistance on the machinability of the titanium alloy Ti555-3

The Ti533-3 alloy is a new titanium alloy which is starting to see increased use in the aeronautical domain to improve the durability of components and to optimize the weight/resistance ratio. This alloy is characterized by greater resistance compared to the more commonly used titanium alloys such as Ti6Al4V. However, a disadvantage of the Ti533-3 alloy is that it is very difficult to machine. In this work, the use of laser-assisted machining has been tested to improve chip formation by a thermal softening phenomenon and to improve the machining productivity of the alloy. A parametric investigation of laser assistance on the machinability of the Ti555-3 titanium alloy shows that: (1) the cutting forces can be greatly decreased if the surface temperature is high; (2) the thermal gradient induced by laser heating modifies the surface integrity in terms of strain hardening and residual stresses in the workpiece; and (3) the chip formation mechanisms are also changed, by increasing the sawteeth frequency when using laser assistanc

Identification of material constitutive laws representative of machining conditions for two titanium alloys: Ti6Al4V and Ti555-3

Determining a material constitutive law that is representative of the extreme conditions found in the cutting zone during machining operations is a very challenging problem. In this study, dynamic shear tests, which reproduce, as faithfully as possible, these conditions in terms of strain, strain rate, and temperature, have been developed using hat-shaped specimens. The objective was to identify the parameters of a Johnson–Cook material behavior model by an inverse method for two titanium alloys: Ti6Al4V and Ti555-3. In order to be as representative as possible of the experimental results, the parameters of the Johnson–Cook model were not considered to be constant over the total range of the strain rate and temperature investigated. This reflects a change in the mechanisms governing the deformation. The shear zones observed in hat-shaped specimens were analyzed and compared to those produced in chips during conventional machining for both materials. It is concluded that the observed shear bands can be classified as white-etching bands only for the Ti555-3 alloy. These white bands are assumed to form more easily in the Ti555-3 alloy due to its predominately β phase microstructure compared to the Ti6Al4V alloy with a α + β microstructure

Etude du comportement en sollicitations extrêmes et de l'usinabilite d'un nouvel alliage de titane aeronautique : le ti555-3

The titanium alloy Ti555-3 is starting to have many aeronautical applications. However the machining of this material raises certain difficulties. This study aims to analyze the machinability of this alloy and compare it to a reference alloy, Ti-6Al-4V. Three aspects have been explored. Instrumented orthogonal cutting tests have been conducted and chip morphology is investigated. This study provided insight into the influence of different cutting parameters or the machining conditions on the machinability of Ti555-3. Thus, the evolution of cutting forces, the temperature in the cutting zone, the morphology of the chip and the evolution of the residual stresses have been highlighted. High strain rate shear tests have been undertaken to replicate the observations obtained under machining conditions and to identify, by the inverse method, the Johnson-Cook material behavior used in the finite element simulation of chip formation. An investigation of High Pressure Water Jet Assisted Machining (HPWJAM) was conducted at different cutting speeds and feed rates. The different chip forms are discussed. The residual stresses generated by HPWJAM were studied. This analysis shows that this technique results in residual surface stresses that are more compressive. The use of laser assisted machining (LAM) is investigated to increase many aspects of the machinability of titanium alloys. This study showed a highly significant influence of laser power on the cutting forces and surface integrity of machined parts.L'alliage de titane Ti555-3, qui commence à être utilisé dans le domaine aéronautique, soulève des difficultés spécifiques en usinage. Cette étude propose d'analyser l'usinabilité de cet alliage et de la comparer à un alliage de référence, le Ti-6Al-4V. Trois aspects ont été explorés. Des essais de coupe orthogonale instrumentés ont été réalisés avec examen de la morphologie des copeaux. Cette étude a permis d'entrevoir l'influence de différents paramètres de coupe sur les conditions d'usinage sur l'usinabilité du Ti555-3. Ainsi l'évolution des efforts de coupe, des températures dans la zone de coupe, la modification de la morphologie du copeau et les évolutions des contraintes résiduelles ont pu être mis en évidence. Des essais de comportement en cisaillement rapide ont permis de reproduire les observations faites sur l'usinage et de proposer l'identification de la loi de Johnson-Cook des matériaux que nous avons ensuite utilisés dans des simulations de formation de copeaux. Une étude sur l'usinage assisté jet d'eau haute pression (UAJEHP) a été menée à différentes vitesses de coupe et d'avance, avec assistance haute pression et à sec. Les copeaux obtenus ont été examinés géométriquement. Les contraintes résiduelles du matériau généré par l'UAJEHP ont été étudiées, leurs analyses ont permis de constater que cette technique réduit le niveau maximal des contraintes résiduelles superficielles. L'utilisation de l'usinage assisté Laser (UAL) permet d'accroitre de nombreux aspects de l'usinabilité des alliages de titane. Cette étude a permis de montrer une influence très significative du la puissance laser sur les efforts de coupe et sur l'intégrité de surface des pièces usinées

High pressure water jet assisted machining of duplex steel: machinability and tool life

High pressure water jet assisted turning (HPWJAT) consists of projecting a high pressure water jet, up to several hundred bar, into the tool-workpiece interface. The water jet is directed between the chip and the tool affording greater protection of the cutting face and better chip breaking. Comparisons are made between assisted turning using several jet pressures and conventional turning with different cutting speeds on the duplex stainless steel, X2CrNiMo22-5. The results show good chip fragmentation and an improvement of tool life with high pressure water jet assistance (HPWJAT). The evolution of the roughness is also investigated. It is shown that it is possible to improve the productivity by using HPWJAT.This study was undertaken by the Arts et Métiers ParisTech CER Angers in collaboration with two industrial partners: CETIM and Westafalia

Laser-assisted machining of Inconel 718 with carbide and ceramic inserts

Laser assisted machining (LAM) can improve the machinability of materials by locally heating the material prior to its removal. The work presented here is a study of the laser assisted machining of Inconel 718 (NiCr19FeNb at 46 HRc) with carbide and ceramic insert. The tests have shown a reduction in the cutting force, and have highlighted the impact of laser assistance on the integrity surface (roughness, appearance, residual stress) and the tool life

Identification de lois de comportement représentatives des conditions d’usinage pour des alliages de titane à différentes teneurs alpha/beta

Determining a material constitutive law which is representative of the extreme conditions found in the cutting zone during machining operations is a very challenging problem. In this study, dynamic shear tests, which reproduce, as faithfully as possible, these conditions in terms of strain, strain rate and temperature, have been developed using hat-shaped specimens. The objective was to identify the parameters of a Johnson-Cook material behaviour model by an inverse method for three titanium alloys: Ti6Al4V, Ti555-3 and Ti17. In order to be as representative as possible of the experimental results, the parameters of the Johnson-Cook model were not considered to be constant over the total range of the strain rate and temperature investigated. This reflects a change in the mechanisms governing the deformation. The shear zones observed in hat-shaped specimens were analysed and compared to those produced in chips during conventional machining for both materials. It is concluded that, in the Ti555-3 alloy, the proportion of alpha-phase greatly reduces in high strain-rate zones

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Etude du comportement en sollicitations extrêmes et de l'usinabilité d'un nouvel alliage de titane aéronautique (le TI555-3)

L alliage de titane Ti555-3, qui commence à être utilisé dans le domaine aéronautique,soulève des di fficultés spécifi ques en usinage. Cette étude propose d analyser l usinabilité de cetalliage et de la comparer à un alliage de référence, le Ti-6Al-4V. Trois aspects ont été explorés. Desessais de coupe orthogonale instrumentés ont été réalisés avec examen de la morphologie des copeaux. Cette étude a permis d entrevoi r l influence de différents paramètres de coupe sur les conditions d usinage sur l usinabilité du Ti555-3. Ainsi l évol ution des efforts de coupe, des températures dans la zone de coupe, la modification de la morphologie du copeau et les évolutions des contraintes résiduelles ont pu être mis en évidence. Des essais de comportement en cisaillement rapi de ont permis de reproduire les observations faites sur l usinage et de proposer l identificati on de la loi de Johnson-Cook des matériaux que nous avons ensuite utilisés dans des simulations de formation de copeaux. Une étude sur l usinage assisté jet d eau haute pression (UAJE HP) a été menée à di fférentes vitesses de coupe et d avance, avec assistance haute pression et à sec. Les copeaux obtenus ont été examinés géométriquement. Les contraintes résiduelles du matériau généré par l UAJE HP ont ét é étudiées, leurs analyses ont permis de constater que cette technique réduit le ni veau maximal des contraintes résiduelles superficiell es. L utilisation de l usinage assisté Laser (UA L) permet d accroitre de nombreux aspects de l usinabilité des alli ages de titane. Cette étude a permis de montrer une i nfl uenc e très signi ficati ve du l a puissance laser sur les efforts de coupe et sur l intégrité de surface des pièces usinées.The titanium alloy Ti555-3 is starting to have many aeronautical applications. However the machining of this material raises certain di fficulties. This study aims to analyze the machinability of this alloy and compare it to a reference alloy, Ti -6Al-4V. Three aspects have been explored. Instrumented orthogonal cutting tests have been conducted and chip morphology is investigated. This study provided insight into the influence of different cutting parameters or the machining conditions on the machinability of Ti555-3. Thus, the evolution of cutting forces, the temperature in the cutting zone, the morphology of the chip and the evolution of the residual stresses have been highlighted. High strain rate shear tests have been undertaken to replicate the observations obtained under machining conditions and to identify, by the inverse method, the Johnson-Cook material behavior used in the finite element simulation of chip formation. An investigation of High Pressure Water Jet Assisted Machining (HPWJAM) was conducted at different cutting speeds and feed rates. The di fferent chip forms are discussed. The residual stresses generated by HPWJAM were studied. This analysis shows that this technique results in residual surface stresses that are more compressive. The use of laser assisted machining (LAM) is investigated to increase many aspects of the machinability of titanium alloys. This study showed a highly signi ficant influence of laser power on the cutting forces andsurface integrity of machined parts.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF