Thermal analysis of wood-steel hybrid construction

Main goal of this work is to present a numerical model to study the thermal necrosis due a dental drilling process, with and without water irrigation. Also an experimental methodology is used to measure the thermal occurrence in a pig mandible. Motivation, the assessment of bone damage, using the temperature criterion (above 55ºC

Advances in Laser Materials Processing

Laser processing has become more relevant today due to its fast adaptation to the most critical technological tasks, its ability to provide processing in the most rarefied and aggressive mediums (vacuum conditions), its wide field of potential applications, and the green aspects related to the absence of industrial cutting chips and dust. With the development of 3D production, laser processing has received renewed interest associated with its ability to achieve pointed to high-precision powder melting or sintering. New technologies and equipment, which improve and modify optical laser parameters, contribute to better absorption of laser energy by metals or powder surfaces and allow for multiplying laser power that can positively influence the industrial spread of the laser in mass production and advance the existing manufacturing methods. The latest achievements in laser processing have become a relevant topic in the most authoritative scientific journals and conferences in the last half-century. Advances in laser processing have received multiple awards in the most prestigious competitions and exhibitions worldwide and at international scientific events. The Special Issue is devoted to the most recent achievements in the laser processing of various materials, such as cast irons, tool steels, high entropy alloys, hard-to-remelt materials, cement mortars, and post-processing and innovative manufacturing based on a laser

Active thermography for the investigation of corrosion in steel surfaces

The present work aims at developing an experimental methodology for the analysis of corrosion phenomena of steel surfaces by means of Active Thermography (AT), in reflexion configuration (RC). The peculiarity of this AT approach consists in exciting by means of a laser source the sound surface of the specimens and acquiring the thermal signal on the same surface, instead of the corroded one: the thermal signal is then composed by the reflection of the thermal wave reflected by the corroded surface. This procedure aims at investigating internal corroded surfaces like in vessels, piping, carters etc. Thermal tests were performed in Step Heating and Lock-In conditions, by varying excitation parameters (power, time, number of pulse, ….) to improve the experimental set up. Surface thermal profiles were acquired by an IR thermocamera and means of salt spray testing; at set time intervals the specimens were investigated by means of AT. Each duration corresponded to a surface damage entity and to a variation in the thermal response. Thermal responses of corroded specimens were related to the corresponding corrosion level, referring to a reference specimen without corrosion. The entity of corrosion was also verified by a metallographic optical microscope to measure the thickness variation of the specimens

Tribology of Machine Elements

Tribology is a branch of science that deals with machine elements and their friction, wear, and lubrication. Tribology of Machine Elements - Fundamentals and Applications presents the fundamentals of tribology, with chapters on its applications in engines, metal forming, seals, blasting, sintering, laser texture, biomaterials, and grinding

Fatigue and Fracture of Traditional and Advanced Structural Alloys

The fatigue behavior of traditional and advanced materials is a very relevant topic in different strategic applications impacting and affecting our daily lives. The present Special Issue invites papers to update readers on the state of the art on this important topic. Both review and original manuscripts are welcome. Special attention will be dedicated to innovative materials and innovative manufacturing processes or post-treatments able to improve the fatigue life and reliability of a structural component. Scale effect will be also fully treated focusing on different applications and multiscale approaches aimed at understanding structural integrity under cyclic loadings. This state of the art perspective will help engineers, designers and people from the academy gain an updated view on this very challenging topic which is nowadays very important due to the advances in manufacturing technologies that allow complex new materials to be fabricated

Laser Cladding for use in Extreme Tribological Interfaces

Coatings are common in engineering applications for protecting the surface of components, either from exposure to environmental conditions or from contact with other components. Laser cladding is a coating technique which allows for thicker coatings of various alloys that enable high load bearing interfaces to operate at a wider range of loads or for longer, for example by increasing durability. This is of great benefit to the railways industry as well as other heavy industries, such as the steel industry. Laser clad coatings have been used extensively in other industries such as oil and gas for increasing the durability of drilling components; in mining and earth moving equipment, for increasing the durability of the components that come in contact with hard soil and rocks. Both are extreme interfaces. In this study, new interfaces and extreme conditions for new industries are investigated, by highlighting the laser clad coating advantages, when used under extreme conditions. The extreme test conditions have not been investigated in published literature, especially with the use of laser clad coatings. This project evaluated the performance of laser cladding coatings on railway components such as the wheel and rail. Other interfaces found in machinery in the steel industry were considered, specifically in the rolling of steel. A variety of interfaces were evaluated by modelling and testing, such as rolling-sliding, high pressure water jet erosion and impact. Three clad materials were identified as suitable for the chosen interfaces, martensitic stainless steel (MSS), Stellite 6 (Co-Cr) and a two-layer clad of Inconel 625 with Technolase. The clad parameters were fixed, resulting in constant material grades, allowing the coatings used in different interfaces to be comparable. The materials choice was based on published research on similar interfaces. Tests were performed on existing test rigs for rolling-sliding and bending tests. The impact test was performed on a rig modified specifically for this study, while a bespoke rig was built for the erosion test. Metallographic techniques were used for all materials, to prepare the samples for characterisation using optical and electron microscopy, as well as nanoindentation and microhardness. Pre- and post-test material analysis was performed. The use of computer modelling was considered mainly for the generation of test parameters, while the results from testing were compared to existing data. Key findings highlight that the use of the selected clad materials under the chosen extreme interfaces can have a positive effect on the durability of the coating, mainly by increasing the wear resistance properties of the coating. Furthermore, the two-layer clad coating showed promising results in stopping crack propagation to the substrate. The test results can be used in predictive tools by researchers in academia, as well as in industry, as a way of introducing laser cladding applications to interfaces of engineering products. Furthermore, the performance of the chosen materials indicates that this study may be used as the basis for selecting similar clad coatings for pilot trials or large scale testing

Quantification of phase transformation in metastable stainless steels after laser surface modification

Aquest estudi investiga els efectes de la modificació de la superfície per làser en la microestructura i les propietats de l'acer inoxidable austenític metestable. La superfície de les mostres d'acer inoxidable 301LN va ser modificada utilitzant un làser de pulso nanosegon. Es van variar dos paràmetres principals del làser, com la intensitat (I) i la velocitat de varrido (S), per evaluar la seva influència en les propietats de la superfície modificada. Es van utilitzar tècniques de caracterització com la difracció de raigs X (XRD), microscòpia electrònica de varrido (SEM) i la prova de duresa Vickers per evaluar la microestructura i les propietats de la zona tractada. Els resultats indicuen que la modificació de la superfície per làser pot millorar significativament la duresa de la superfície de l'acer inoxidable. Aquest estudi destaca el potencial de la modificació de la superfície per làser com un mètode viable per millorar les propietats de duresa de l'acer inoxidable i proporciona una guia per identificar els paràmetres òptims del làser per a aplicacions específiques.Este estudio investiga los efectos de la modificación superficial con láser sobre la microestructura y las propiedades del acero inoxidable austenítico metaestable. Se modificó la superficie de muestras de acero inoxidable 301LN utilizando un láser pulsado de nanosegundos. Se variaron dos parámetros principales del láser, como la intensidad (I) y la velocidad de barrido (S), para evaluar su influencia en las propiedades de la superficie modificada. Se utilizaron técnicas de caracterización como la difracción de rayos X (DRX), la microscopía electrónica de barrido (MEB) y el ensayo de dureza Vickers para evaluar la microestructura y las propiedades de la zona tratada. Los resultados indican que la modificación superficial con láser puede mejorar significativamente la dureza superficial del acero inoxidable. Este estudio pone de relieve el potencial de la modificación superficial con láser como método viable para mejorar las propiedades de dureza del acero inoxidable y proporciona orientación para identificar los parámetros óptimos del láser para aplicaciones específicas.This study investigates the effects of laser surface modification on the microstructure and properties of metastable austenitic stainless steel. The surface of 301LN stainless steel samples was modified using a nanosecond pulsed laser. Two main laser parameters such as intensity (I) and scanning speed (S) were varied to evaluate their influence on the modified surface properties. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Vickers hardness testing were utilized to evaluate the microstructure and properties of the treated zone. Results indicate that laser surface modification can significantly enhance the surface hardness of stainless steel. This study highlights the potential of laser surface modification as a viable method for improving the hardness properties of stainless steel and provides guidance for identifying the optimal laser parameters for specific applications