Browsing by Author "Santos Vilaca da Silva, Pedro"

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    Application of Friction Stir Welding and Allied Techniques to Aluminium
    (2014) Santos Vilaca da Silva, Pedro; Department of Engineering Design and Production
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    Application of Hybrid Friction Stir Channeling (HFSC) technique to improve the cooling efficiency of electronic components
    (2017) Karvinen, Heikki; Nordal, Daniel; Galkin, Timo; Santos Vilaca da Silva, Pedro; Department of Mechanical Engineering; Engineering Materials; Nokia
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    Characterization of friction surfaced coatings of aisi 316 tool over high-speed-steel substrate
    (University of Zagreb, 2017) Kumar, Ravi; Chattopadhyaya, Somnath; Ghosh, Aniruddha; Krolczyk, Grzegorz M.; Santos Vilaca da Silva, Pedro; Kumar, Ratnesh; Srivastava, Madhulika; Shariq, Mohammad; Triphathi, Rupam; Indian Institute of Technology Dhanbad; GCETT Berhrampore; Opole University of Technology; Department of Mechanical Engineering
    Nowadays friction surfacing (FS) has become a popular solid state surface coating technology suitable for a range of substrates. The technology has the ability to produce coatings with marginal dilution and good metallurgical bonding. The present study has aimed at producing a single-Track and a three-Track overlapping coatings on high-speed steel substrates using an AISI 316 consumable rod. Microhardness of coatings was examined by a Vickers micro hardness tester. Coatings of all the friction surfaced samples in as-deposited condition showed significant hardness. The infrared thermography showed that the peak temperature achieved by the AISI 316 coating was about 1020 ? C. The coatings, thus attained, were further analysed for their microstructural features and interfacial characteristics by using FE-SEM. The EDX analysis showed the presence of nickel, chromium and oxygen, which indicates the formation of oxide compounds. The formation of AISI 316 deposits on the HSS substrate and the effect of coating overlapping are discussed in this article.
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    Characterization of FSW of Aluminium to Copper for Electrical Busbars
    (2018-07-15) Olafsson, Dagur; Santos Vilaca da Silva, Pedro; Vesanko, Jussi; Department of Mechanical Engineering; Engineering Materials; Promeco Oy
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    Comparison of fatigue behaviours of AA5052 H32 butt joints fabricated by the CW‐GMAW and FSW processes
    (2016-09) Ribeiro, Rafael A.; Assuncao, Paulo D. C.; Infante, Virgínia; Santos Vilaca da Silva, Pedro; Pina Cipriano, Goncalo; Moreira, Pedro M.G.P.; Braga, Eduardo M.; Department of Mechanical Engineering; Engineering Materials; Universidade Federal do Pará; University of Lisbon; University of Porto
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    Effect of Microstructure on the Fatigue Behavior of a Friction Stirred Channel Aluminium Alloy
    (Elsevier, 2013) Vidal, Catarina; Infante, Virgínia; Santos Vilaca da Silva, Pedro; Department of Engineering Design and Production
    The influence of microstructure on fatigue behavior was investigated on a friction stirred channel strain hardened 5083-H111 aluminium alloy. Friction Stir Channeling (FSC) is an innovative solid-state manufacturing technology able to produce continuous, integral channels in a monolithic plate in a single step. Four sets of FSC parameters were implemented in order to obtain channels with different microstructure and geometry. Fatigue tests were carried out under four-point bending loading. Detailed metallographic, geometric and fractographic analyses were obtained via OM and SEM. It is shown that the fatigue strength is dependent on the channel’s nugget (friction stir zone) width.
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    Effect of processing temperatures on the properties of high strength steel welded by FSW
    (2017) Lourenco Sorger, Goncalo; Sarikka, Teemu; Santos Vilaca da Silva, Pedro; Santos, Telmo G.; Department of Mechanical Engineering; Engineering Materials; NOVA University Lisbon
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    Effect of second pass in 2-sided FSW of high-strength structural steel
    (2014) Luumi, Lauri; Santos Vilaca da Silva, Pedro; Sato, Yutaka S.; Hänninen, Hannu; Kokawa, Hiroyuki; Department of Engineering Design and Production; Tohoku University
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    Effect of titanium on the weldability of thermomechanically rolled high-strength cold-formable steels
    (2017) Mourujärvi, Juho; Tihinen, Sakari; Mehtonen, Saara; Lahtinen, Teemu; Santos Vilaca da Silva, Pedro; Kaijalainen, Antti; Porter, David; Kömi, Jukka; Department of Mechanical Engineering; Engineering Materials; University of Oulu; SSAB Europe Oy
    This research is concerned with the effect of titanium in the range 0.01 to 0.13 wt. % on the base plate and weldability properties of laboratory hot-rolled cold-formable steels with yield strengths in the range 500 - 900 MPa (S500MC - S900MC). Different strength levels were achieved by varying the contents of boron, chromium, molybdenum and manganese. For the base metal, titanium had a small strengthening effect and it also raised the impact transition temperature. In MAG welding (t8/5 = 5 s), titanium had a strengthening effect probably due to precipitation strengthening which was seen both in the strength of the welded steels and in the lower hardness difference between the base metal and the HAZ. Titanium, especially with higher concentrations, had a clear negative effect on the impact toughness of the fusion line and a somewhat smaller negative effect on the impact toughness of the fusion line + 1 mm position. This was probably due to the presence of large angular TiN inclusions promoting cleavage crack nucleation. Also unlike small TiN particles precipitated from the solid state, these inclusions are ineffective in preventing austenite grain coarsening in the coarse-grained HAZ (CGHAZ). Overall, high titanium contents have been shown to have a detrimental effect on HAZ properties: although titanium reduces the softening of the HAZ experienced in these types of steels, it has a clear negative effect on the HAZ impact toughness with low heat input.
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    An Experimental Investigation of the Yield Parameters in Friction Surfacing Using Factorial Design of Experiment
    (2014) Chattopadhyaya, Somnath; Mukhopadhyay, Prithviraj; Santos Vilaca da Silva, Pedro; Department of Engineering Design and Production; Indian Institute of Technology Dhanbad
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    Fatigue behavior of MAG welds of thermo-mechanically processed 700MC ultra high strength steel
    (ELSEVIER SCI LTD, 2019-09-01) Lahtinen, Teemu; Santos Vilaca da Silva, Pedro; Infante, Virginia; Department of Mechanical Engineering; Advanced Manufacturing and Materials
    The present work analyzes the weldability of 8 mm thick plates of commercially available modern high strength steel with minimum yield strength of 700 MPa. The weldability is improved by modeling the welding conditions to evaluate and support the extensive analysis of the mechanical and the metallurgical properties of the welds. Materials were welded by a two-pass MAG process with four different heat inputs. All the welds and respective base materials underwent fatigue tests, tensile tests and hardness measurements. In tensile tests, the strains were measured using digital image correlation (DIC) equipment. Fatigue fracture surfaces were investigated for the highest and lowest loads tested using scanning electron microscopy. The failures in tensile and in fatigue tests occurred in the recrystallized HAZ. DIC measurements revealed that in tensile tests the strain localized in the domain of minimum hardness. The accumulative effect of both welding passes lowered the strength and hardness at the root side, making the root side more sensitive to weakening, as shown by hardness profiles. In addition, increasing the heat input lowered the fatigue strength of the welds. The welds had 150–300 MPa lower maximum fatigue strength (R=0.1) than the base material.
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    From Conventional to Hybrid Friction Stir Channeling: Milestones and Characterization
    (2018-07-15) Karvinen, Heikki; Nordal, Daniel; Santos Vilaca da Silva, Pedro; Department of Mechanical Engineering; Engineering Materials
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    Microstructural characterization of alloy 926 and 2205 duplex stainless steels coating layers deposited over high strength steel by friction surfacing
    (2018-07-15) Shekh Mohammad, Arju; Casanova, Jaime; J. S. de Souza, Gustavo; Santos Vilaca da Silva, Pedro; Brandi, Sérgio Duarte; Department of Mechanical Engineering; Engineering Materials; Department of Mechanical Engineering; Universidade de São Paulo
    Friction surfacing (FS) is a solid state processing technique used to deposit thick coating layers over a substrate enabling several metallic combinations. FS can be used in the production of new components or as a repair technique, typically to recover base metals from corrosion or wear loading. In this paper, UNS N08926 and UNS S32205 duplex stainless steels were investigated as consumable rods for coating a substrate made of S700MC grade high strength steel. The FS was applied under controlled plunging speed. Rods with dimensions of 180 mm long and 12 mm in diameter were used to deposit a coating with approximately 100 mm in length. The rods were made of duplex stainless steels. An L-9 Taguchi experimental design was used to optimize and study the effect of the rod rotational speed, the rod feed speed (Vz), and the travel speed (Vx) on the coating geometrical characteristics and its microstructure. The rotational speed was changed from 1500 to 2500 rpm, the plunging speed from 2.0 to 3.0 mm/s and the traverse speed from 350 to 550 mm/min. The FS was done without inert gas protection. The geometry of the resulting coating was characterized by a stereoscopic equipment. The microstructures were analyzed by optical microscopy and by EBSD technique, at center, advancing side and retreating side. The thermal profiles were assessed by IR camera and thermocouples. Results show a difference in the austenite volumetric fraction using both characterization techniques, but the trend of the results were similar. Both duplex stainless steels presented an austenite percentage lower than the original rods percentages. In the case of UNS N08926, the minimum volumetric fraction was 1.0% and the maximum austenite content was 18.0%, compared to 26.0% in the original rod. For UNS S32205, the minimum value was 20.0% and the maximum austenite volumetric fraction was 40.0%, compared to 48.0% in the original rod. Also, the amount of austenite at the advancing side was larger than at the retreating side, and both larger than at the middle of the coating. These results can be explained by the thermal cycles and by the plastic deformation. The optimal welding parameter maximized the volumetric fraction of austenite in the three regions of the FS coating. Keywords: Friction surfacing; Duplex stainless
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    My Innovations stirred by wunderbar Dos Santos
    (2018-10-12) Santos Vilaca da Silva, Pedro; Department of Mechanical Engineering; Engineering Materials
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    Process Developments and Materials Characterization in FSW/P
    (2014) Miranda, Rosa M.; Gandra, João; Santos, Telmo G.; Quintino, Luísa; Santos Vilaca da Silva, Pedro; Department of Engineering Design and Production
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    Recent developments in FSW assisted by electrical current hybrid process
    (2017) Santos, Pedro; Oliveira, J. P.; Inácio, Patrik L.; Chen, Yingchun; Santos Vilaca da Silva, Pedro; Miranda, R.M.; Santos, Telmo G.; Department of Mechanical Engineering; Engineering Materials; NOVA University Lisbon; Ohio State University
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    Solid state welding of dissimilar materials
    (2018-08-23) Santos Vilaca da Silva, Pedro; Department of Mechanical Engineering; Engineering Materials
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    Thermal Efficiency and Material Properties of Friction Stir Channelling Applied to Aluminium Alloy AA5083
    (MDPI AG, 2019-04-24) Karvinen, Heikki; Hasani Aleni, Afshin; Salminen, Pauli; Minav, Tatiana; Santos Vilaca da Silva, Pedro; Department of Mechanical Engineering; Advanced Manufacturing and Materials; Solid Mechanics
    The Friction Stir Channelling (FSC) is a novel advanced solution for producing internal closed channels along any desired path with a constant or continuously modified shape along the path in a single manufacturing step. The channels are formed by continuous extraction of part of the stirred processed material into external flash. In this work, the performance of channels with the same shape and dimensions but produced by FSC and milling respectively, are compared using an experimental calorimeter setup with a focus on the influence of the geometrical features of the channels on the thermal efficiency. The investigation is implemented in a plate of AA5083-H111, with a thickness of 10 mm. The material properties of the channels produced by FSC are investigated with a microhardness field and optical microscopic analysis, assessing the thermomechanically processed and heat affected zones. The mechanical resistance of the channels produced by FSC is evaluated with an application of internal pressure up to 380 bar. The results show that the FSC enhanced the heat transfer by about 45 % compared with smoother milled channels. The optical microscopy shows evidence of a good consolidation of the solid state joining mechanisms activated during the FSC, with a small reduction of the hardness around the channel in the stirred zone and heat affected zone, being assisted by a harder top region at the ceiling of the channel.