Rodrigo Santiago Coelho

• Dr.-Ing.
• Professor (Associate) at SENAI CIMATEC Bahia

The use of parts containing internal channels fabricated by laser powder bed fusion (LPBF) in maraging steel is gaining attention within industry, due to the promising application of the material in molds and forming tools. However, LPBF processing has issues when it comes to unsupported channels, leading to defects that can result in a limited per...

Super-duplex stainless steels (SDSSs) were introduced in the oil and gas industry due to their high resistance to pitting corrosion, promoted by the high content of alloying elements. The welding process can cause an unbalanced ferrite/austenite microstructure and, consequently, the possibility of deleterious phases, increasing the risk of failure....

In the context of the Product Development Process (PDP), particularly during the development phase, there is growing recognition of the importance of waste management in producing components used in the industry. This increased awareness has led to a progressive interest in formulating approaches to understand and mitigate the possible resulting en...

High-strength steels such as Dual Phase (DP), Transformation-Induced Plasticity (TRIP), and Twinning-Induced Plasticity (TWIP) steels have gained importance in automotive applications due to the potential for weight reduction and increased performance in crash tests. However, as resistance increases, there is also an increase in springback due to r...

Objective: This study aims to develop and empirically test a derivation of the Technology Acceptance Model (TAM) on the acceptance of electric vehicles (EV). Theoretical Approach/Method: The analysis was based on an original theoretical model adapted from the TAM, a theory based on information systems that models how users start to accept and use a...

The production of carbide parts (cermet) by additive manufacturing, such as laser powder bed fusion (L-PBF), has been a great challenge due to the complex optimization of process parameters to improve density, porosity, microcracks or abnormal growth of grains and obtain a microstructure as homogeneous as possible. This work aims to compare the evo...

The excellent casting behavior and mechanical and corrosion properties of aluminum-silicon (Al-Si)-based alloys make them ideal for the manufacture of lightweight components with complex geometries. However, these properties depend directly on their microstructure, which, in its turn, is strongly affected by the composition of the alloy, among othe...

Boron-manganese steel 22MnB5 is extensively used in structural automotive components. Knowledge about its microstructural evolution during hot stamping and resistance spot welding (RSW) is extremely relevant to guarantee compliance with application requirements. Particularly, corrosion properties are critical to the application of uncoated sheet st...

The automotive industry has always relied on innovation to drive its growth, with Ford Motor Company at the forefront of this transformation. Today, digital transformation is a key focus, with technologies such as AI, big data, and blockchain being used to improve personalized user experiences, develop connected and autonomous vehicles, optimize su...

Tungsten alloys have attracted attention in different industrial areas, such as biomedical and military devices, in the application of shielding for ionizing radiation. In this study, samples of W-30Ni alloy were additively fabricated by the laser beam selective Powder Bed Fusion-Laser (PBF-L) techniques, and compared with the conventional route, l...

In Additive Manufacturing by Electron Beam Fusion, Lumbar fusion prostheses have been the preference of manufacturers as the Additive Manufacturing by Electron Beam Fusion process enables the construction of complex and optimized geometries for application in high-scale production. The relevant standards for the mechanical validation of this produc...

The use of ultra-high-strength steels (UHSS) has been growing in recent years, mainly in the automotive industry. Since these steels have high strength and hardness, more applied stresses are required to deform them, probably also impacting friction behaviour. In this article, a variation in the process parameters commonly observed in sheet-metal f...

The friction that occurs in forming processes plays a fundamental role in the industry as it can be responsible for both manufacturing failure and its success. Scientific research has been done to try to understand this phenomenon as well as simulation software has been implemented aiming to predict the tribological behavior of the metallic pair in...

In order to gain a comprehensive view of electric vehicles (EVs) technologies and understand the emphasis of current research, this study evaluated the most relevant themes related to EVs through a bibliometric analysis using the keyword “electric vehicle” as the input. The Web of ScienceTM (WoS) database was used because it is considered ideal for...

Microstructural and crystallographic aspects arising from thermomechanical processing of a Ti–6Al–4V alloy in β and α+β phase fields were studied by electron backscatter diffraction and both conventional and high energy synchrotron X-ray diffraction. The impact of deformation in the single β field on the final microstructure has been acknowledged b...

The SARS-CoV-2 pandemic in Brazil has grown rapidly since the first case was reported on 26 February 2020. As the pandemic has spread, the low availability of medical equipment has increased, especially mechanical ventilators. The Brazilian Unified Health System (SUS) claimed to have only 40,508 mechanical ventilators, which would be insufficient t...

The austenitic stainless steels are a group of alloys normally used under high mechanical and thermal requests, in which high temperature oxidation is normally present due to oxygen presence. This study examines the oxide layer evolution for Fe24Cr12NiXNb modified austenitic stainless steel A297 HH with 0,09%Nb and 0,77%Nb content at 900°C under at...

In this study, GMAW and CMT welding technologies were evaluated in terms of their technological lifecycles based on their patent datasets together with the S-curve concept, and the joints were evaluated in terms of their welding characteristics. To predict the future trends for both technologies, different models based on the time-series and growth...

In the current world scenario, which is experiencing the arrival of new technologies, Industry 4.0, increased mobility and a pandemic environment, the achievement of sustainability demands proactive solutions. One of these actions includes the design of sustainable products. Several authors have studied the scientific discipline of Life Cycle Engin...

The modified ASTM A297 Gr. HH austenitic stainless steels are a group of refractory alloys designed for high temperature applications that required elevated mechanical strength, such as those found in petrochemical furnace structures and in the steel industry. This study examines the overall microstructural features and cyclic oxidation behaviour o...

Reliable high temperature operation of refractory metals depends on the mechanical integrity of the protective oxide formed on the material surface. The residual stress state in oxide layers developed on two modified Nb-alloyed ASTM A297 HH austenitic stainless steels, thermal expansion analysis of the substrate, steel micro-structure, oxide layers...

Phase transformations in a lamellar Ti–5Al–5Mo–5V–3Cr–1Zr (Ti-55531) alloy upon heating at continuous rates of 5, 20 and 100 °C/min has been studied by in situ high energy X-ray diffraction (HEXRD), aided by scanning and transmission electron microscopy, atom probe tomography and hardness measurements. During slow heating, the β phase has shown a b...

Aiming to decrease friction coefficient ( μ ) during the forming of magnesium alloy sheets, nine (9) tools with different hole geometries in their surface (flat, elliptical, and circular) were manufactured from steel Boehler W400 VMR (as known as DIN 1.2343). Tribological investigations were accomplished on a strip drawing machine at 288 °C without...

The aging behavior of a Ti-6Al-4V alloy with different starting microstructures was evaluated by means of synchrotron X-ray diffraction, scanning-transmission electron microscopy and micro-hardness measurements. Initial microstructures were produced by thermal and thermomechanical treatments and comprised different morphologies of α phase (martensi...

The impact of starting microstructure on the isothermal behavior of β-metastable Ti–5Al–5Mo–5V–3Cr alloy during aging at 400 °C for 8 h was studied by means of in situ synchrotron X-ray diffraction. Results show that prior deformation does not accelerate phase precipitation during heating, but has an influence on secondary α precipitation during ag...

Due to their applicability for manufacturing dense, hard and stable coatings, Physical Vapor Deposition (PVD) techniques, such as High Power Impulse Magnetron Sputtering (HiPIMS), are currently used to deposit transition metal nitrides for tribological applications. Cr-Al-N is one of the most promising ceramic coating systems owing to its remarkabl...

Austempered ductile irons exhibit an interesting combination of properties such as low cost, elevated strength, fatigue and wear resistance. In the present contribution, the influence of shot-peening on the dry-sliding wear behavior of as-cast and austempered ductile irons was evaluated. Specimens from a casting with an initial ferritic-pearlitic m...

This work encompasses the study of the mechanical behavior of single lap joints (SLJ) with similar and dissimilar materials, joined by epoxy adhesives. The objective was to analyze the effect of the variables overlap length (OL), adhesive thickness (AT) and adherends yield strength (YS) over the SLJ failure load (FL). The stress state of the joints...

The performance of perovskite films in capacitor devices is strongly determined by the level of residual stresses developed after their fabrication at high temperatures. Quantification of these stresses by X-ray diffraction is not straightforward in perovskite films due to the complexity of the crystalline structure and a lack of effective elastic...

In friction surfacing (FS), material is deposited onto a substrate in the plasticized state, using frictional heat and shear stresses. The coating material remains in the solid state and undergoes severe plastic deformation (SPD) at high process temperatures (≈0.8 Tmelt), followed by high cooling rates in the range of 30 K/s. Dynamic recrystallizat...

The conventional sheet metal forming processes, such as deep drawing and stretch forming, are used to produce large batches of parts, however they incur in higher initial manufacturing costs attributed to the use of a large amount of tooling. The application of conventional and incremental forming processes combined in the same metal sheet is calle...

Structural adhesives methods for joining multi material sheets have been focus of studies and researches for the last years. The most common and widely known type of test is the tensile test of single lap joints (SLJ). However, there are opportunities for analyzing the mechanical performance of such method in SLJ with materials of different propert...

Commercially pure titanium (CP Ti) is of great importance in medical applications due to its attractive properties, such as high biocompatibility, excellent corrosion resistance and relatively low density and suitable stiffness. Compared to the commonly used Ti-6Al-4V alloy, its lower strength has to be increased. The most attractive approach is to...

The use of Superduplex Stainless Steel, on Oil & Gas productive process equipment and piping, meet the requirements of high corrosion resistance, due to their high PREN (Pitting Resistance Equivalent Number), and excellent mechanical properties. However, these steels, because of the high alloy addition, can suffer loss of corrosion resistance and e...

We report on in-situ high temperature X-ray thermal stress analysis of chemically graded Ti(C,N) coatings deposited on functionally graded cemented carbide substrates by chemical vapor deposition. The in-situ analyses were performed by energy dispersive X-ray diffraction using synchrotron radiation. The samples were subjected to one individual ther...

Resumo: O contínuo interesse na redução do peso de estruturas e produtos industriais tem elencado constantes discussões sobre o uso de novos materiais de baixo peso em juntas e estruturas mecânicas de materiais dissimilares. Em veículos automotores, por exemplo, a redução de peso impacta diretamente na redução do consumo de combustível e de emissõe...

The deformation behavior of the Mg-RE alloys ME21 and WE54 was investigated. Although both alloys contain rare earth elements, which alter and weaken the texture, the flow curves of the alloys deviate significantly, especially in uniaxial compression test. Apart from the higher strength of the WE54 alloy, the compression flow curve does not exhibit...

We investigated the stress behaviour of Ti(C,N) coatings deposited on WC-Co substrates during an individual thermal cycle. The stress analyses were performed in-situ by energy dispersive X-ray diffraction using a white synchrotron beam. The stresses were determined using the sin²ψ method combined with scattering vector measurements at the strain-fr...

This study presents experimental evidence for the sequence of activation and the evolution of primary tension (TTW), secondary compression (CTW) and tertiary double twinning (DTW) in an extruded Mg–4 wt%Li alloy during uniaxial compression by means of in-situ and ex-situ EBSD and (HR-)TEM. In-situ EBSD analysis reveals that the secondary CTWs propa...

In this work, the casting process under mechanical agitation in the semi-solid state was investigated for the production of ZK60 magnesium alloy modified with the addition of 2.5% wt of mischmetal. The results show that this process enables the production of ingots with homogeneous chemical composition and free of shrinkage, inner defects and inter...

In this work, we report on the friction stir weldability of a semi-solid cast ZK60 alloy modified with 1.5 wt% mischmetall in the lap-joint configuration using a 120WV4 steel tool with concave shoulder and conical pin. The coarser solidification microstructure in the semi-solid cast ZK60-1.5%RE alloy requires low strain rates and increased heat inp...

Possibilities for depth resolving texture analysis applying energy-dispersive X-ray synchrotron diffraction are presented. Exploiting the advantage of having the complete diffraction spectra observed in a fixed but arbitrary measuring direction, two different approaches for high spatial resolution analyses are discussed. The first allows fast acces...

A comparative analysis of mechanical properties and forming behavior of extruded sheets of AZ31 and ME21 magnesium alloys is presented. The mechanical properties were determined by tensile tests in different loading directions and the forming behavior was investigated by hot deep drawing tests. Both magnesium sheets exhibit a mechanical anisotropy...

The present work deals with the effect of different combinations of induction heating and autogenous CO2 laser welding on the gradients of microstructure, microhardness and residual stresses in butt-joints of thermomechanically processed S500MC steel grade. Five strategies were pursued by varying the inductor position with respect to the laser beam...

In this work we investigate the thermal residual stress behavior during thermal cycling treatment of Ti(C,N) coatings deposited by chemical vapor deposition (CVD) on WC-Co cemented carbides. Residual stresses are measured in as-coated and top-blasted conditions. The carbonitride coatings present a gradient of C/N composition. Therefore the stress s...

The use of light-weight materials for industrial applications is a driving force for the development of joining techniques. Friction stir welding (FSW) inspired joints of dissimilar materials because it does not involve bulk melting of the basic components. Here, two different grades of high strength steel (HSS), with different microstructures and...

Responding to a growing interest from the materials science community for residual stress, texture, and microstructure analysis, strong efforts are made to enhance existing and develop novel methods that allow for fast in-situ studies at elevated temperature, measurements under external load, or residual strain, and stress scanning with high spatia...

Two new approaches that make use of the advantages of energy dispersive diffraction were applied to investigate through-thickness variations of the crystallographic texture: the `real-space' and the `Laplace-space' methods. The first consists of defining a small gauge volume by adding a pair of slits in the primary and the diffracted beams. Thus th...

The present chapter covers the microstructural development of friction stir welds (FSW), their corrosion behaviour and mechanical properties. The section on microstructural aspects of friction stir welds presents a general description of the different weld zones and their main characteristics. The sub-structural evolution of an AlMgSc alloy is desc...

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The material flow characteristics of butt-joints between AA6181-T4 Al alloy and high strength DP600 steel was investigated. The investigations involved analyses by scanning electron microscopy (SEM) combined with electron back-scattered diffraction (EBSD). EBSD is a SEM add-on package that allows local crystallographic analysis of crystalline micro...

A study was conducted to demonstrate the production of sound overlap friction welds between the AA6181-T4 and the HC340LA steel. The welding parameters chosen ensure high surface quality joints and the absence of macro cracks after the welding process. The maximum force of the friction stir welded joints obtained in shear test amounts to 73% of the...

Microstructure and properties of a Mg AZ31B laser beam weld without filler are studied using electron microscopy, X-ray diffraction and mechanical tests. The microstructure of the weld is characterized by a narrow heat affected zone, columnar grains and precipitate coarsening in the fusion zone. Texture in the fusion zone is significantly different...

Microstructure, hardness and residual stresses of the laser beam overlap welds between AZ31B sheets and AZ31, AZ61 and AZ80 extruded profiles are investigated using microscopy and X-ray diffraction. The result of the investigations reveal that weld microstructure, the size of the HAZ, precipitate density and the maximum compressive residual stress...

Conference presentation

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