Non-destructive residual stress analysis and microstructural behaviour of laser deposited titanium and copper alloy

Abstract: Titanium alloy (Grade 5) has been regarded as the most useful alloys for the aerospace applications, due to their light weight properties. The addition of copper to this alloy allows the improvement in the mechanical properties. The increase in the laser power has influenced the coarseness of the α-Ti lamella; and thus slows down the cooling rate during solidification. The X ray diffraction method has been used to analyse the residual stresses using the biaxial and shear-stressed model. Very infinitesimal microns were taken into consideration for the penetration depth. The results generated indicate that a decrease in the compressive residual stresses is attributed to the increase in the laser power and the variation of the heat input within the clad during processing. The differences in the thermal expansion with respect to the increase in the volume of deposition as the laser power increases have significant effect on the compressive residual stress

Central composite design on volume of laser metal deposited Ti6Al4V and Cu

Abstract: Laser technology process is a pulsating practice to the field of engineering and in all paces of lifespan; since it can travel a longer distance and be focused to a very small bright spot that exceeds the illumination of the sun. This present study reports the modeling and the prediction of the volume of laser deposited composites using the central composite design (CCD). Four input factors were put into consideration which is the laser power, the scanning speed, the powder flow rate and the gas flow rate. Titanium alloy (Ti6Al4V) and copper (Cu) have been coaxially deposited to form a bulk of single clad. The factors considered determine the energy density and the melt pool delivered into the substrate and as such, influenced the volume of the deposited composite (VDC) which was employed in the response surface methodology (RSM) design. This has been used to predict the actual process parameters for the optimum process setting

Influence of laser power on the surfacing microstructures and microhardness properties of Ti-6Al-4V-Cu alloys using the ytterbium fiber laser

Abstract: Laser Metal Deposition (LMD) is a route that involves the spraying of metallic powders onto a substrate with the application of beam of light. The deposition of titanium alloy (Ti-6Al-4V) with five weight percent (5 wt %) of copper (Cu) has been explored and characterized through the developing microstructures and microhardness. A constant scanning speed of 0.3 m/min and laser powers varied between 400 W and 1600 W were used for the process parameters. The Widmanstatten structures were even at low laser powers and later increased in their coarseness and propagate further as the laser power increases; and the occurrence can be attributed to the further increase in the heat input from the top of the clad to the substrate and the slow cooling rate within the cladded zone of the composites. A typical sample D4 deposited with a laser power of 1000 W exhibits the highest hardness value of 541 ± 88 HV0.5 while sample D2 deposited at a laser power of 600 W depicts the lowest hardness value of 448 ± 58 HV0.5. The properties of the Ti-6Al-4V-Cu alloys have been improved and can be recommended for marine application

A review article: the mechanical properties and the microstructural behaviour of laser metal deposited Ti-6Al-4V and TiC composite

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Effect of laser power on the microstructural behaviour and strength of modified laser deposited Ti6Al4V+CU alloy for medical application

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Effect of scanning speed and powder flow rate on the evolving properties of laser metal deposited ti-6al-4v/cu composites

Abstract: In Laser Metal Deposition (LMD), good bonding between two similar or dissimilar materials can be achieved if the interrelationships between the processing parameters are well understood. LMD samples of titanium alloy, Ti-6Al-4V and copper, Cu were produced by varying the scanning speed and keeping other parameters constant. The deposited samples were characterized through the volume of deposited composites, microstructure, microhardness and the degree of porosity. The effect of the optimized high (powder flow rate) PFR, scanning speed varying from 0.06 m/min to 1.2 m/min and a constant power of 1kW led to a degree of porosity on the deposited composites. The varying percentages of porosities in the samples have an advance merit effect in the implantation of bones in animal and human. It was found that the existence of pores reduced as the scanning speed increases. The Vickers mirohardness was observed to increase with an increase in the scanning speed which shows an improvement in the properties of the Ti-6Al-4V/Cu composites. At low scanning velocity, the microstructure appears coarse due to the high rate of powder deposited at the same power of 1kW. The α-phase acicular microstructure decreases in size and thickness with an increase in the scanning speed. Widmanstätten structure was found in the scanning electron microscopy analyses. The results show that high PFR and low scanning speed have significantly influenced the evolving properties of the deposited composites

Exploration of microstructure and wear behaviours of laser metal deposited Ti6Al4V/Cu composites

Abstract: This paper reports on the investigations conducted on the evolving microstructures and the dry sliding wear of the laser deposited Ti6Al4V/Cu composites. Some selected process parameters were used for the experiments. The laser powers were chosen between 1300 W and 1600 W; scanning speeds were selected between 0.30 m/min and 0.72 m/min while other parameters are as specified in the experimental matrix. It was found that all the composites produced showed good and high-quality microstructures and they exhibited very low or no fusion zones which were as a result of the selected process parameters used. The α-phase region of the composites was found to be harder than the β-phase region. During the composites cooling, the β-phase field transformed to the basal planes of the hexagonal α-phase thereby creating a lower diffusion coefficient of the α-phase as compared to the β-phase counterpart. The Ti6Al4V/Cu composite produced at a laser power of 1397 W and a scanning speed of 0.3 m/min was found to show the lowest percentage of wear volume and coefficient of friction; and happened due to the martensitic structure formed during cooling. Results obtained showed that the poor abrasive wear of titanium alloy has been improved with the addition of copper into their lattices

Effect of powder density variation on premixed Ti-6Al-4V and Cu composites during laser metal deposition

Abstract: This paper reports the effect of powder density variation on the premixed Ti-6Al-4V/Cu and Ti-6Al-4V/2Cu Composites. Two sets of experiment were conducted in this study. Five deposits each were made for the two premixed composites. Laser powers were varied between 600 W and 1700 W while a scanning speed of 0.3 m/min is kept constant throughout the experiment. Investigations were conducted on the microstructures and microhardness of the laser deposited premixed Ti-6Al-4V/Cu and Ti-6Al-4V/2Cu composites. It was found that the evolving microstructures of the composites were characterised with the formation of macroscopic banding and Widmanstatten; and disappears as it grows towards the fusion zone (FZ) and this could be attributed to the changes in the distribution of heat input. Sample A2 of premixed Ti-6Al-4V/Cu composite gives the highest hardness of 393 ± 6.36VHN0.5 while sample B4 of premixed Ti-6Al-4V/2Cu composites depicts the highest hardness value of 373 ± 9.18VHN0.5

Behaviour of laser metal deposited Ti6Al4V/Cu composites in hank’s solution for biocompatibility properties

Abstract: Ti6Al4V alloy is a well-known material for biomedical application due to the very excellent corrosion resistance it possessed. Copper is an excellent antimicrobial property and has been found to stabilize the immune system of the body activities. In this present study, laser metal deposition of Ti6Al4V/Cu composites have been conducted by varying the laser power between 600 W and 1800 W while the scanning speed of 0.005 m/s and other process parameters as depicted in the experimental matrix were kept constant. Widmanstettan structures were observed in all the samples at high magnification and lose their coarseness as the laser power increases. The microhardness values of the deposited composites were varied between HV335 ± 27 μm and HV490 ± 73 μm. The surface behaviour and the morphologies of the composites were evaluated under the SEM after soaking for 2 weeks. The simulated body fluid (hank’s solution) was maintained at normal body temperature of about 37±1oC. The surfaces showed fracture topography with porous bone-like and snowflake structures

Laser metal deposition of Ti6Al4V/Cu composite : a study of the effect of laser power on the evolving properties

A study of the effect of laser power was investigated over the volume of deposited composite, microstructure and microhardness. The laser power was varied between 600 and 1800 W while keeping all other parameters constant. An indication shows that the area and the volume of the deposited composites are directly proportional to the laser power employed. The volume of the deposit obtained falls between 358.6 mm3 and 1009 mm3. The microstructures were analyzed and found that the formation of the Widmanstatten structures improved the hardness of Ti6Al4V/Cu composites. The hardness values of the deposits varied between HV335 and HV490. The percentages of porosities of the samples were also presented and found to have an inverse relationship with the laser power. The results are presented and discussed