This work presents a comprehensive experimental study on the effect of pulsed laser ablation (Yb-fiber) on Ti6Al4V titanium alloy substrates for adhesive bonding. The modification of surface ...morphology and chemistry is assessed by means of SEM, XRD and wettability measurements. In addition, surface and subsurface mechanical properties are probed through an extensive series of instrumented indentation tests. Based on the results of the aforementioned analyses, a suitable processing window is identified and adhesive bonded T-peel joints are fabricated and tested. The obtained results indicate that pulsed laser irradiation can substantially improve the performance of Ti6Al4V/epoxy joints.
In this work the effect of femtosecond Yb fiber laser irradiation on Ti6Al4V titanium alloy is assessed. An extensive experimental campaign is carried out to survey surface properties through the use ...of SEM, AFM, EDS mapping and contact angle measurements. It is shown that the generation of uniform nanoscale laser induced periodic surface structures (LIPSS) allows to tailor surface properties and improves adhesive bonding with epoxy resin. The potential of the technique to improve the durability of the joints against accelerated aging is also evaluated.
This work presents a methodology to fabricate zeolite coating on aluminum and magnesium alloys. A procedure for coating AA 6082 aluminum and AZ31B magnesium alloys substrates with a homogeneous, ...adherent and anticorrosive layer of a zeolite filler embedded in a silane matrix is developed. The adhesion of the coating has been probed by scratch and shear tests. Furthermore, the coating strength at high strain rate has been tested by tensile impact testing method. Also, the corrosion resistance of the coated samples has been verified highlighting an improvement with respect to the uncoated materials. The overall results show a very good surface coverage grade and a good level of coating adhesion and strength.
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•An extensive experimental campaign on machining 7075-T6 aluminum alloy at varying cutting parameters is presented.•High cycle fatigue tests were performed to obtain the fatigue ...endurance of the products at varying surface conditions.•An adapted analytical model is presented to reduce the number of destructive tests needed.•The model well predicts the fatigue endurance as a function of surface integrity induced by different process conditions.
The metallurgical, mechanical and topographical modifications induced by machining strongly influence the surface quality of the final components which, in turn, dictates the functional performance and service-life of engineered products. This paper aims to extensively discuss the effect of machining parameters and cooling/lubrication strategies on the high cycle fatigue strength of 7075-T6 aluminum alloy. More in detail, three different cutting speeds (90, 120 and 150 m/min) and four cooling/lubrication methodologies (dry, cryogenic, minimum quantity lubrication and high pressure air jet) have been analyzed. The obtained fatigue samples have been tested under fully reversed stress conditions in the high cycle fatigue regime. An adapted analytical model, taking into account the effect of the surface changes, is also proposed in order to drastically reduce the number of destructive tests needed assessing the effects of the processing parameters on the overall fatigue endurance.
Burnishing is considered a super finishing process able to drastically increase surface quality in terms of hardness and roughness of the manufactured parts. Consequently, it is considered appealing ...for the performance enhancement of products where the surface quality plays a crucial role. However, when burnishing grade 5 titanium alloy, a quantitative relationship between process parameters and surface integrity is still missing. This work provides a deep analysis of the burnishing parameters and their influence on the surface integrity of Ti-6Al-4V. In particular, starting from a large experimental campaign, statistical analysis of the results is performed and models able to describe the surface integrity response based on different burnishing parameters are presented. The overall results allow us to clearly define the relationship within the input and output variables identifying, by the proposed models, different operational windows for surface integrity improvement.
Purpose: This paper aims to provide a flexible solution to include additive manufacturing into a process chain complying with Industry 4.0 pillars, overcoming major drawbacks in terms of reliability ...and experimental effort. Design/methodology/approach: The study is based on the combination of real experimental activities and simulated ones. Findings: The main findings of this work consist into validation of the proposed process chain, which proves to be effective in terms of process flexibility (additive manufacturing, burnishing and process simulation acting synergistically), cost and time reduction and final output quality, encouraging customer involvement towards customization. Originality/value: This paper contributes to current research on the application of burnishing process, an easy to implement and environmentally friendly post-processing method to improve the performance of AM products, by providing a unique perspective integrating a reliable simulation model. Other researchers can employ these outcomes towards manufacturing of the future.
This paper presents a customized FE model for describing the microstructural changes during dry and cryogenic cutting of Ti6Al4V. It addresses the importance to modify the material behavior taking ...into account the microstructural changes and the cooling/lubrication effects during the cutting process. With this aim, a user subroutine is implemented in the FE code to describe the surface and subsurface modifications taking place during the cutting process and to implement them in order to properly modify the material flow stress. Thus, the material flow stress is continuously updated during the simulation according to the new microstructure characteristics. The proposed FE model is calibrated and validated by comparison with experimental results.
This work proposes an approach to fabricate micro patterned surfaces on PA2200 polyamide in order to improve its performance in terms of wettability and adhesion. In more detail, the present work ...aims to change the wettability of the surface and decrease their bacteria adhesion tendency. The experimental procedure consists of imprinting a set of different micro patterned structures over the polymer in order to verify the effectiveness of the methodology to change the contact angle of the surface, and in turn, reduce the occurrence of bacteria adhesion. Four different surface patterning were produced by laser ablation of a commercially pure titanium alloy, and then imprinted over the polyamide by surface stamping. The resulting surfaces were analyzed by topographical characterization and scanning electron microscopy. The wettability was probed by contact angle measurements while the bacteria adhesion was analyzed by adhesion test. The experimental results demonstrate the effectiveness of the method to modify the surface characteristics and to obtain a reliable patterned surface without using chemical hazardous material; opening to the possibility to replicate more complex structures and to obtain graded engineering surfaces.
Surface and subsurface microstructural characterization after machining operations is a topic of great interest for both academic and industrial research activities. This paper presents a newly ...developed finite element (FE) model able to describe microstructural evolution and dynamic recrystallization (DRX) during orthogonal hard machining of SAE 8620 steel. In particular, it predicts grain size and hardness variation by implementing a user subroutine involving a hardness-based flow stress and empirical models. The model is validated by comparing its output with the experimental results available in literature at varying the cutting speed, insert geometry and flank wear. The results show a good ability of the customized model to predict the thermo-mechanical and microstructural phenomena taking place during the selected processes.
This paper presents an extensive experimental study on the influence of machining parameters and cooling conditions on the overall fatigue life of a titanium component. In particular, dry, minimum ...quantity lubrication, cryogenic and high-pressure air jet were compared as cooling/lubrication strategies for the finishing operation. The obtained dog-bone cylindrical fatigue specimens were tested under uniaxial pull–pull cyclic loading in the high cycle fatigue range. An analytical model is proposed to predict the high cycle fatigue strength for the material under investigation demonstrating its effectiveness to reduce the number of tests needed.
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