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Garcia-Vazquez F.,Autonomous University of Coahuila | Vargas-Arista B.,Tlalnepantla Institute of Technology | Muniz R.,Autonomous University of Coahuila | Ortiz J.C.,Autonomous University of Coahuila | And 2 more authors.
Soldagem e Inspecao | Year: 2016

Aluminum alloys are very promising for structural applications in aerospace, military and transportation industries due to their light weight, high strength-to-weight ratio and excellent resistance to corrosion. In comparison to unreinforced aluminum alloys, aluminum/aluminum alloy matrix composites reinforced with ceramic phases exhibit higher strength and hardness, improved tribological characteristics. A novel surface modifying technique, friction stir processing (FSP), has been developed for fabrication of surface composite with an improved performance. The effect of FSP parameters such as number of passes, direction of each pass, sealed or unsealed groove on microstructure was investigated. In this work, nano-particles of TiC (2% in weight) were added to aluminum alloy AA7075-T651 to produce a functional surface. Fixed parameters for this AA7075 alloy were used; rotation speed of 1000 rpm, travel speed of 300 mm/min and pin penetration of 2.8 mm. Optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the microstructure of the fabricated surface composites. The results indicated that the selected FSP parameters influenced the area of surface composite, distribution of TiC particles and micro-hardness of the surface composites. Finally, in order to evaluate rate wear the pin on disk test was carried out. © 2016, Universidade Federal de Uberlandia. All rights reserved.


Mata O.C.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Perez A.F.M.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Medina G.Y.P.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Vazquez F.J.G.,Autonomous University of Coahuila | Arizmendi A.,CIMAV
Soldagem e Inspecao | Year: 2016

Advancement in automotive part development demands new cost-effective materials with higher mechanical properties and improved wear resistance as compared to existing materials. For instance, Aluminum Matrix Composites (AMC) shows improved mechanical properties as wear and abrasion resistance, high strength, chemical and dimensional stability. Automotive industry has focused in AMC for a variety of applications in automotive parts in order to improve the fuel economy, minimize vehicle emissions, improve design options, and increase the performance. Wear resistance is one of the most important factors in useful life of the automotive components, overall in those components submitted to mechanical systems like automotive brakes and suspensions. Friction Stir Welding (FSW) rises as the most capable process to joining AMC, principally for the capacity to weld without compromising their ceramic reinforcement. The aim of this study is focused on the analysis of wear characteristics of the friction-stir welded joint of aluminum matrix reinforced with 20 percent in weight silicon carbide composite (A359/SiC/20p). The experimental procedure consisted in cut samples into small plates and perform three welds on these with a FSW machine using a tool with 20 mm shoulder diameter and 8 mm pin diameter. The wear features of the three welded joints and parent metal were analyzed at constant load applying 5 N and a rotational speed of 100 rpm employing a Pin-on - Disk wear testing apparatus, using a sapphire steel ball with 6 mm diameter. The experimental results indicate that the three welded joints had low friction coefficient compared with the parent metal. The results determine that the FSW process parameters affect the wear resistance of the welded joints owing to different microstructural modifications during welding that causes a low wear resistance on the welded zone. © 2016, Universidade Federal de Uberlandia. All Rights Reserved.


Tahaei A.,University of Ferrara | Vazquez F.G.,Corporacion Mexicana de Investigacion en Materiales Comimsa | Merlin M.,University of Ferrara | Arizmendi-Morquecho A.,CIMAV | And 2 more authors.
Soldagem e Inspecao | Year: 2016

In this investigation, a nickel-base powder mixed with tungsten carbide particles was applied by Plasma Transferred Arc welding (PTA) on the surface of the D2 cold work tool steel to improve surface quality and to extend its lifetime during applications. The Design of Experiment (DoE) method was applied to obtain the appropriate combination of hardfacing parameters and to run the minimum number of tests. Current, travel speed and preheat were considered as variable parameters. These parameters are important to reach a final layer with an appropriate bead geometry accompanied with good metallurgical properties. All samples were prepared for metallurgical investigations and the effect of process parameters on the weld bead geometry was considered. For each experiment run, weld bead geometry parameters were measured including dilution, penetration and reinforcement. Microstructures and the distribution of tungsten carbide particles after welding were analyzed by Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) equipped with an EDS microprobe. In addition, hardness tests were performed to evaluate the mechanical properties of the weld bead layers. Finally, among all the experiments, the best sample with appropriate bead geometry and microstructure was selected. © 2016, Universidade Federal de Uberlandia. All Rights Reserved.


Praga-Alejo R.J.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Gonzalez-Gonzalez D.S.,Autonomous University of Coahuila | Cantu-Sifuentes M.,Corporacion Mexicana de Investigacion en Materiales COMIMSA
International Journal of Advanced Manufacturing Technology | Year: 2015

In this paper, the Ridge method is applied to improve radial basis function neural network. The resulting redesigned radial basis function is built to test the statistical significance in an array of independent variables considering the existence of a collinearity problem, as well as obtaining appropriate assumptions for concluding those significances. The radial basis function allows the determination of a relationship between a response, and one or more independent variables, determining the importance of each factor for the model. However, this testing may obtain negative results, when one or more columns of the design matrix are linearly dependent; for this reason, we have adapted the Ridge method for the radial basis function. The results show that the variance inflation factor is a good metric alternative for validating the effectiveness of neural network inference. Our primary conclusion is that the redesigned radial basis function results in improved model accuracy when combined with the Ridge method. Additionally, this model can also be used to validate the statistical assumptions required to find the sources of the multicollinearity in an analysis, discovering the corrections and interpreting the model. © 2015, Springer-Verlag London.


Perez A.F.M.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Breda M.,University of Padua | Calliari I.,University of Padua | Medina G.Y.P.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Sandstrom R.,KTH Royal Institute of Technology
Soldagem e Inspecao | Year: 2016

The austeno-ferritic Stainless Steels are commonly employed in various applications requiring structural performances with enhanced corrosion resistance. Their characteristics can be worsened if the material is exposed to thermal cycles, since the high-temperature decomposition of ferrite causes the formation of detrimental secondary phases. The Submerged Arc Welding (SAW) process is currently adopted for joining DSS owing to its relatively simple execution, cost savings, and using molten slag and granular flux from protecting the seam of atmospheric gases. However, since it produces high contents of d-ferrite in the heat affected zone and low content of γ-austenite in the weld, high-Ni filler materials must be employed, to avoid excessive ferritization of the joint. The present work is aimed to study the effect of 3 and 6 hours isothermal heat treatments at 850°C and 900°C in a SAF 2205 DSS welded joint in terms of phases precipitation. The results showed the presence of s-phase at any time-temperature combination, precipitating at the σ/γ interphases and often accompanied by the presence of σ-phase. However, certain differences in secondary phases amounts were revealed among the different zones constituting the joint, ascribable both to peculiar elements partitioning and to the different morphology pertaining to each microstructure. © 2016, Universidade Federal de Uberlandia. All Rights Reserved.


Praga-Alejo R.J.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Cantu-Sifuentes M.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Gonzalez-Gonzalez D.S.,Autonomous University of Coahuila
Expert Systems with Applications | Year: 2015

Generally, statistical methods and mathematical models are useful for process optimization. Nonetheless, other methods might be used for modeling and optimizing the manufacturing process. Among these, we can mention the neural networks and the Radial Basis Function technique. Hence, a suitable alternative is complementing statistical methods and neural networks as a Hybrid Learning Process. This work applies the Radial Basis Function Canonical Analysis in order to achieve the welding process optimization. One of the most important results is that the Radial Basis Function neural networks along with the Canonical Analysis are really useful methods. These methods are applied for predicting the optimal point, which establishes a reliable method for the process modeling and optimizing. The Canonical Analysis can determine stationary and saddle points, as it was in this case of study, which Canonical Analysis with RBF represented it adequately and can plot a surface and contour lines. Since in this case of study there is a surface that contains a ridge saddle system, also often called minimax. Then the results show that the Canonical Analysis can explore the region with oblique stationary and rising ridge systems. In this way, the RBF neural network with Canonical Analysis could be an alternative method for analyzing data, whenever the Hybrid Learning Process is adequate or satisfies the test assumption and fulfills the evaluation criteria. In this case of study, validation is represented by the Hybrid Learning Process (Radial Basis Function with Canonical Analysis) presenting an excellent effectiveness. As a conclusion we can say that the resulting Radial Basis Function has improved the model accuracy after using the Canonical Analysis. © 2015 Elsevier B.V. All rights reserved.


Medina G.Y.P.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Padovani M.,University of Ferrara | Merlin M.,University of Ferrara | Perez A.F.M.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Valdes F.A.R.,Corporacion Mexicana de Investigacion en Materiales COMIMSA
Materials Research Society Symposium Proceedings | Year: 2015

Gas tungsten arc welding-tungsten inert gas (GTAW-TIG) is focused in literature as an alternative choice for joining high strength low alloy steels; this study is performed to compare the differences between gas metal arc welding-metal inert gas (GMAW-MIG) and GTAW welding processes. The aim of this study is to characterize microstructure of dissimilar transformation induced plasticity steels (TRIP) and martensitic welded joints by GMAW and GTAW welding processes. It was found that OMAW process lead to relatively high hardness in the HAZ of TRIP steel, indicating that the resultant microstructure was marten- site. In the fusion zone (FZ), a mixture of phases consisting of bainite, ferrite and small areas of martensite were present. Similar phase's mixtures were found in FZ of GTAW process. The presence of these mixtures of phases did not result in mechanical degradation when the GTAW samples were tested in lap shear tensile testing as the fracture occurred in the heat affected zone. In order to achieve light weight these result are benefits which is applied an autogenous process, where it was shown that without additional weight the out coming welding resulted in a high quality bead with homogeneous mechanical properties and a ductile morphology on the fracture surface. Scanning electron microscopy (SEM) was employed to obtain information about the specimens that provided evidence of ductile morphology. © 2015 Materials Research Society.


Garcia-Vazquez F.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Guzman-Flores I.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Garza A.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Acevedo J.,Corporacion Mexicana de Investigacion en Materiales COMIMSA
Materials Research Society Symposium Proceedings | Year: 2010

Brazing is a unique method to permanently join a wide range of materials without oxidation. It has wide commercial application in fabricating components. This paper discusses results regarding the brazing process of 304 stainless steel. The experimental brazing is carried out using a nickel-based (Ni-11Cr-3.5Si-2.25B-3.5Fe) filler alloy. In this process, boron and silicon are incorporated to reduce the melting point, however they form hard and brittle intermetallic compounds with nickel (eutectic phases) which are detrimental to the mechanical properties of brazed joints. This investigation deals with the effects of holding time and brazing temperature on the microstructure of joint and base metal, intermetallic phases formation within the brazed joint as well as measurement of the tensile strength . The results show that a maximum tensile strength of 464 MPa is obtained at 1120°C and 4 h holding time. The shortest holding times will make boron diffuse insufficiently and generate a great deal of brittle boride components. © 2010 Materials Research Society.


Praga-Alejo R.J.,Autonomous University of Coahuila | Torres-Trevino L.M.,Autonomous University of Nuevo León | Gonzalez-Gonzalez D.S.,Autonomous University of Coahuila | Acevedo-Davila J.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Cepeda-Rodriguez F.,Corporacion Mexicana de Investigacion en Materiales COMIMSA
Expert Systems with Applications | Year: 2012

The Hybrid Learning Process method proposed in this work, is applied to a Genetic Algorithm and Mahalanobis distance, instead of computing the centers matrix by Genetic Algorithm. It is determined in such a way as to maximize the coefficient of determination R 2 and the Fitness Function depends on the prediction accuracy fitted by the Hybrid Learning approach, where the coefficient of determination R 2 is a global metric evaluation. The Mahalanobis distance is a measurement of distance which uses the correlation between variables and takes into account the covariance and variance matrix in the input variables; this distance helps to reduce the variance into variables. The purpose of this work is to show a methodology to modify the Radial Basis Function and also improve the parameters and variables that are associated with Radial Basis Function learning processes; since the Radial Basis Function has mainly two problems, the Euclidean distance and the calculation of centroids. The results indicated that the statistical methods such as Residual Analysis are good alternatives and excellent methods for validation of the effectiveness of the Neural Network models. The principal conclusion of this work is that the Radial Basis Function Redesigned improved the accuracy of the model using a Hybrid Learning Process and the Radial Basis showed very good performance in a real case, considering the prediction of specific responses in a laser welding process. © 2012 Elsevier Ltd. All rights reserved.


Guzman I.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Granda E.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Mendez R.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | Lopez G.,Corporacion Mexicana de Investigacion en Materiales COMIMSA | And 2 more authors.
Journal of Materials Engineering and Performance | Year: 2013

In this paper, the influence of the cooling rate and cooling media after a standard solution heat treatment on the size and distribution of the gamma prime phase (γ) in the nickel-based super alloy INCONEL 738 in over-aged conditions is described. The volume fraction of the gamma prime depends on the chemical composition of the alloy, the solution treatment temperature and the cooling rate; in over-aged alloys (i.e., with more than 25,000 h of service) the volume fraction of γ is about 78.8%. However, it has been demonstrated that in order to maintain excellent creep strength a volume fraction of at least 60% or lower is required. In this work the volume fraction was optimized between 40 and 55% by means of a standard solution heat treatment at 1120 C using different cooling gases. A γ volume fraction of 54.8% was obtained by using argon as the cooling medium at a cooling rate of 87 C/min, producing a precipitate of partial distribution of primary and secondary γ. Better results were obtained in a nitrogen atmosphere at a cooling rate of 287 C/min, leading to a volume fraction of 40% and obtaining a total re-precipitation of primary and secondary γ. © 2012 ASM International.

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