Computational fluid dynamics and experimental analysis of a coated stainless steel gas turbine blade.

This work Aims to analyze, through computational fluid dynamics (Cfd) with the concept of conjugate heat transfer (Cht), the effect of the Thermal Barrier coating and the cooling systemon an Austenitic Stainless steel blade in order to Evaluate the Temperature Behavior of the Material. Although this Steel has a Lower cost compared to Super ALLOYS, it has Similar Properties, Such as the Thermal Expansion Coefficient, chemical Affinity and Melting point. this Evaluation used Ansys? Cfx Software ot Solve the Numerical Problem. the Systemis Validated by Comparing the computational Results to an Experiment. Gas Turbine Blades have a low weight and an Elevated cost. this cost came Mainly form both the Material used and the Sophisticated coating and cooling Method. Thermal Barrier Coatings Associated to a cooling System are Employed on gas Turbine Blades to Increase the Lifetime of the Blade and the gas Turbine Performance. the study Indicates that the Thermal Barrier coating and ahe cooling System were Efficient At Reducing the Temperature of the Metallic Substrate By 160?C. this can Indicated that Stainless steel Blades can be used in gas turbines where the Metallic Temperature limit was not be reached

Laser cladding and thermal spray coatings on steel pipe serving the oil and gas industry.

Different coating systems were characterized using a commercial API 5CT steel grade L80 type 1, which is commonly used in the oil and gas industry. Two Ni-based alloys and one Co-based alloy were deposited by laser cladding. Two coatings were deposited (Ni-based alloy and a composite W-C/Co-base) by means of thermal spray process. It has been shown the presence of a hard heat affected zone (HAZ) in the substrate for the as-laser deposited coating. The main explanation for this HAZ is devoted to the heat gradient causing a gradient on the prior austenite grain size and consequently different martensite hardness along the HAZ. For the thermal sprayed coatings, no HAZ was formed due to low heat input process. All the studied coating systems seem to be very interesting for different technically demanding applications, such as, stress sulfide corrosion and wear resistance

Evaluation of hydrogen-Induced cracking resistance of the In625 laser coating system on a C-Mn steel substrate.

The corrosion of C-Mn steels in the presence of hydrogen sulfide (H2S) represents a significant challenge to oil production and natural gas treatment facilities. The failure mechanism induced by hydrogen-induced cracking (HIC) in a Inconel 625 coating / C-Mn steel has not been extensively investigated in the past. In the present work, an API 5CT steel was coated with In625 alloy using laser cladding and the HIC resistance of different regions, such as the coating surface, the substrate and HAZ, were evaluated. SEM observations illustrated that all HIC cracks were formed at the hard HAZ after 96h of exposure. No HIC cracks were observed in the substrate and the In625 coating after the same exposure duration. Pitting was recorded in the substrate caused by non-metallic inclusion dissolving

Discontinuity detection in the shield metal arc welding process.

This work proposes a new methodology for the detection of discontinuities in the weld bead applied in Shielded Metal ArcWelding (SMAW) processes. The detection system is based on two sensors?a microphone and piezoelectric?that acquire acoustic emissions generated during the welding. The feature vectors extracted from the sensor dataset are used to construct classifier models. The approaches based on Artificial Neural Network (ANN) and Support Vector Machine (SVM) classifiers are able to identify with a high accuracy the three proposed weld bead classes: desirable weld bead, shrinkage cavity and burn through discontinuities. Experimental results illustrate the system?s high accuracy, greater than 90% for each class. A novel Hierarchical Support Vector Machine (HSVM) structure is proposed to make feasible the use of this system in industrial environments. This approach presented 96.6% overall accuracy. Given the simplicity of the equipment involved, this system can be applied in the metal transformation industries

Characterization of phase transformations and microstructural changes in an API 5CT L80 steel grade during ni alloy laser cladding.

The superficial coatings in micro-alloyed steel pipes has been a pointed way to decrease the corrosion problems in oil and gas industry. However, little emphasis has been given to the substrate. The effects of the deposition method on the steel microstructure and properties are still not well described. In this context, this work studied the effect of Ni superalloys clads on the phase transformations, microstructure and hardness of the heat-affected zone (HAZ) of an API steel. The underestimate of the HAZ might be dangerous, since, despite the coating good corrosion performance, the substrate HAZ may present a weak region, which may lead to an in-service coating tearing. In this work, Inconel 625 and Hastelloy C276 superalloys were clad on the steel surface by a laser deposition. Dilatometry, optical and scanning electron microscopy, and computational simulation were applied. The studied steel was originally constituted by tempered martensite. The austentizing temperature had a strong influence on the austenite grain size and on the steel CCT diagram. Due to that, the laser superalloy deposits promoted a complex HAZ, where grain growth occurred. A post-cladding heat treatment was proposed to homogenize the steel microstructure and to decrease the hardness gradient at the superalloy-steel interface

Effect of different forms of application of a laser surface treatment on fatigue crack growth of an AA6013-T4 aluminum alloy.

This work analyzes the effect of surface-localized laser heating treatment on the fatigue crack growth (FCG) rate on region II of the sigmoidal da/dN 3 DK curve of an aerospace-grade AA6013-T4 aluminum alloy sheet with 1.3 mm thickness. The influence on microstructure changes is also evaluated. Aiming to improve the FCG resistance without changing the mechanical behavior of the alloy, a Yb:fiber laser beam is defocused to generate a laser spot diameter of 2 mm, using 200 W power and a laser speed of 2 mm/s. Two laser lines are applied over fatigue C(T) specimens in two different forms: on only one and on both lateral specimen surfaces. Guinier?Preston zones, dispersoids and coarse constituent particles are found on the base material. On the heat-treated material, the same precipitates and also b? and Q? precipitates are found. These microstructural variations due to the laser thermal cycle, together with the presence of induced compressive residual stresses, improved the fatigue behavior of the material. The FCG retardation is optimized when two laser lines were applied on both lateral surfaces of the specimen

A comparative study of the heat input during laser welding of aeronautical aluminum alloy AA6013-T4.

The heat input is the amount of energy supplied per unit length of the welded workpiece. In this study, the effect of two different heat inputs in laser beam welding of a high strength aluminum alloy AA6013-T4 was evaluated from macrostructural and microstructural points of view. The experiments were performed using a continuous wave 2 kW Yb-fiber laser with 100 ?m spot size on the upper surface of the workpiece. Keeping the heat input at a given level, 13 or 30 J/mm, the laser power was changed from 650 W to 2 kW and the welding speed from 33 to 150 mm/s. In the condition of higher heat input 30 J/mm it was possible to obtain both cutting and welding processes. For 13 J/mm, welding processes were obtained in conduction and keyhole modes. The equiaxed grain fraction changed with changing speed for the same heat input. The laser processing induced a decrease in the hardness of the weld bead of about 25% due to the solubilization of the precipitates. The estimated absorptivities of the laser beam in the liquid aluminum changed largely with experimental conditions, from 4.6% to 10.5%, being the most significant source of error in measuring the real amount of energy absorbed in the process. For the same heat input the macrostructure of the welded surfaces, i.e., humps and dropouts, changed as well. All these facts indicate that the heat input is not a convenient method to parameterize the laser beam welding parameters aiming the same weld features

Laser surface treatment for enhanced titanium to carbon fiber?reinforced polymer adhesion.

The adhesion between carbon fiber-reinforced polymer (CFRP) and titanium parts can be improved by laser surface texturing before gluing them together. Here, a pulsed Nd:YAG laser was employed before bonding of the textured surfaces using an epoxy paste adhesive. To investigate the influence of the laser parameters, the roughness of the surfaces were characterized and correlated to the wettability, by measuring the contact angles of water droplets. Scanning electron microscope (SEM) characterization was also performed showing that under careful conditions, the fiber structure could be maintained. Tensile tests were performed to evaluate the influence of the laser treatment parameters on the joining efficiency. The lap-joint tensile strength tests presented the best results when the titanium surfaces were treated using 5.03 ? 10?3 J pulses and the CFRP sample treated with 5.03 ? 10?4 or 5.03 ? 10?3 J or even using a virginal CFRP surface. Using a virginal CFRP surface, the critical load of fiber delamination was increased and as a consequence the tensile strength attains the highest level of 8.2 MPa

A multi-objective green UAV routing problem.

This paper introduces an Unmanned Aerial Vehicle (UAV) heterogeneous fleet routing problem, dealing with vehicles limited autonomy by considering multiple charging stations and respecting operational re- quirements. A green routing problem is designed for overcoming difficulties that exist as a result of lim- ited vehicle driving range. Due to the large amount of drones emerging in the society, UAVs use and efficiency should be optimized. In particular, these kinds of vehicles have been recently used for deliver- ing and collecting products. Here, we design a new real-time routing problem, in which different types of drones can collect and deliver packages. These aerial vehicles are able to collect more than one deliver- able at the same time if it fits their maximum capacity. Inspired by a multi-criteria view of real systems, seven different objective functions are considered and sought to be minimized using a Mixed-Integer Lin- ear Programming (MILP) model solved by a matheuristic algorithm. The latter filters the non-dominated solutions from the pool of solutions found in the branch-and-bound optimization tree, using a black-box dynamic search algorithm. A case of study, considering a bi-layer scenario, is presented in order to val- idate the proposal, which showed to be able to provide good quality solutions for supporting decision making