Ivani de Souza Bott
Pontifical Catholic University of Rio de Janeiro
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Publication
Featured researches published by Ivani de Souza Bott.
Materials Research-ibero-american Journal of Materials | 2013
A. B. Forero; Milagros. M.G. Núñez; Ivani de Souza Bott
Longitudinal welded joints samples of X70 and X80 API grade steel pipes were exposed to a deaerated 1% NaCl solution containing CO2, at temperatures in the range of 25 oC to 80 oC for 48 hours. Analogous samples were exposed to the adjacent vapour phase. The layer of corrosion products which formed on the base metal and welded regions of the samples was investigated using mass loss determinations, scanning electron microscopy and X-ray diffraction. The corrosion products formed in tests at 60 oC and were composed of FeCO3. The FeCO3 which had initially formed at 80 oC was observed to have subsequently decomposed, resulting in a layer of Fe2O3.
Journal of Materials Engineering and Performance | 2001
Vera Luicia Otheiro de Brito; Herman Jacobus Cornelis Voorwald; Nasareno das Neves; Ivani de Souza Bott
Postweld heat treatment (PWHT) is frequently applied to steel pressure vessels, following the requirements of the ASME code (section VIII), which establishes the parameters of the PWHT based on the thickness and chemical composition of the welded section. This work shows the results of an analysis undertaken on a sample of ASTM A537 C1 steel subjected to qualifying welding procedure tests including PWHT (650°C/5 h). The results obtained showed that this PWHT practice promoted a reduction in the mechanical properties of the base metal and the heat-affected zone (HAZ).Postweld heat treatment (PWHT) is frequently applied to steel pressure vessels, following the requirements of the ASME code (section VIII), which establishes the parameters of the PWHT based on the thickness and chemical composition of the welded section. This work shows the results of an analysis undertaken on a sample of ASTM A537 C1 steel subjected to qualifying welding procedure tests including PWHT (650°C/5 h). The results obtained showed that this PWHT practice promoted a reduction in the mechanical properties of the base metal and the heat-affected zone (HAZ).
Materials Research-ibero-american Journal of Materials | 2015
Adriana Forero Ballesteros; José Antônio da Cunha Ponciano Gomes; Ivani de Souza Bott
The H2S corrosion resistance of API 5L X80 steel and its welded joint (WJ) were evaluated using the weight loss method in a 5%wt brine solution and different corrosive environments based on a sodium thiosulphate solution (10–3 and 10–2 mol/l). The weight loss method, scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) were applied to measure the effects of different H2S concentrations and pH (3 and 5) on the corrosion process and formation of corrosion product films. The results showed that the obtained corrosion rate and corrosion product films for both API 5L X80 steel and its submerged arc welding (SAW) WJ depend on the pH, H2S concentration and metal surface microstructural characteristics. The corrosion product film consists of two layers with different morphologies. The heat affected zone (HAZ) shows severe localized corrosion attack relative to the base metal (BM) and weld metal (WM), which is attributed to the microstructural characteristics of this region.
Materials Science Forum | 2012
R.A. Silva; Gilmar Zacca Batista; L. Felipe G. de Souza; Ivani de Souza Bott
Hot induction bending is a process applied to tubes produced for the oil and gas industry, where bending temperatures above Ac3 can be reached. The base metal is submitted to two thermal cycles, one during welding, generating the heat affected zone (HAZ), and another during bending when this HAZ is reheated. Also, after the bending process is completed, heat treatment is required, which represents a third thermal cycle. The objective of the present work was to compare the effect of two different induction bending process conditions on the longitudinal SAW weld of two API 5L X80 steel pipes of 20” diameter, 19mm thickness, Pcm of 0.17% and Σ NbTiV of 0.11%. The pipes, were produced by the UOE process from a steel plate obtained by thermomechanical processing without accelerating cooling. The bending parameters applied were 105 kW power at 2500 Hz frequency and 205 kW at 500Hz A major microstructural decomposition of the welded joint occurred for the 205 kW / 500Hz condition due to the higher heat input in function of the doubled power input during bending. These microstructural changes led to an inversion of the microhardness profile from the internal pass to the external pass as compared to the welded joint before bending. Tensile strength values obtained after bending were above the minimum limit (621MPa) established for grade X80 by the API 5L norm, showing that these microstructural changes promoted by the bending process do not compromise the structural integrity of the joint.
Materials Science Forum | 2013
Antonio José Mendes Gomes; Jorge Carlos Ferreira Jorge; Luís Felipe Guimarães de Souza; Ivani de Souza Bott
The present work is part of a wide research program which the main goal is the development of welding procedures for chain and accessories for application in mooring systems of oil platforms. In the specific case of the work in subject, the development of different covered electrodes formulations is discussed for obtaining high mechanical strength and impact toughness, of the order of 860 MPa and 50 joules at –20°C, respectively. Welded joints using the developed electrodes were prepared for evaluation of the mechanical properties, using preheat of 200°C, direct current, flat position and heat input of 1.5 kJ/mm. After welding, tensile, impact Charpy-V and hardness tests were performed in specimens removed integrally from the weld metal, both in as welded and heat treated conditions. The post weld heat treatment (PWHT) was conducted at 600°C for 1, 2 and 3 hours. The results shows that the obtained weld metals have mechanical properties higher than the minimum required for the welding of a IACS W22 R4 Grade steel, and particularly good impact properties, which indicates that the correct control of the chemical composition, particularly, of Mn-Ni balance, makes possible to achieve an adequate strength/toughness relationship for high strength steel weld metals, where the PWH is mandatory. In addition, it was verified that the increase in the time of PWHT did not promote substantial impairment on mechanical properties.
Welding International | 2010
Humberto N. Farneze; Jorge Carlos Ferreira Jorge; Luís Felipe Guimarães de Souza; Ivani de Souza Bott
A comparative study of the clad electrode and tubular wire processes was carried out, looking at the mechanical and micro-structural properties of weld metals of high-resistance steel, in the ‘as-welded’ and ‘stress-relief heat treatment’ (PWHT) conditions. The results show that the procedures adopted for welding with tubular wire and clad electrodes allow satisfactory levels of mechanical resistance to be obtained, with the exception of the value of percentage lengthening of the tubular wire, in the as-welded condition. The impact tests show that both the weld metals showed satisfactory impact resistance, in both the as-welded and PWHT conditions, observing that, for the tubular wire, the impact resistance is lower for the clad electrode in both conditions, lying close to the limit applied for the acceptance criterion of 50 J at 0°C in the PWHT condition. It was confirmed that the productivity achieved by the tubular wire process was approximately twice as high as that for the clad electrode process. As a result, the inherent advantage of the tubular wire process must be complemented with a consideration of all the mechanical properties obtained, orienting suitable selection of the welding process, in particular, for application in equipment that operates in fatigue conditions.
Materials Science Forum | 2007
Franc A. Martins; José Antônio Cunha Ponciano; Ivani de Souza Bott
Many steels tubes used in the Oil Industry are constantly exposed to hydrogen sulphide (H2S) which can lead to the diffusion of hydrogen into the steel, potentially provoking hydrogen embrittlement and/or stress corrosion cracking. Additionally the critical region in pipelines is usually considered to be the welded joints. In this work SAW welded joints of two API steels, grades X80 and X70, were evaluated using laboratory tests according to the NACE TM0177/96 METHOD A Standard and the slow strain rate test (SSRT) using a sodium thiosulphate solution. The results indicate that both steel grades can be susceptible to HE and SCC, since loss of ductility when submitted to SSRT and failure under NACE TM0177/96 METHOD A were observed.
Volume 3: Materials and Joining; Pipeline Automation and Measurement; Risk and Reliability, Parts A and B | 2006
Gilmar Zacca Batista; Leonardo Naschpitz; Eduardo Hippert; Ivani de Souza Bott
The present work discusses the effect of the induction hot bending process on the microstructure and the mechanical properties of an API 5L X80, 20” pipe produced by the UOE process. The key characteristic of the pipe was the manufacturing process of the steel plate, involving thermomechanical controlled rolling without accelerated cooling. The pipe bending was carried out applying local induction heating followed by water quenching and a further temper heat treatment which was applied to the curved section. The methodology of analysis compared the curved section with the original body pipe (tangent end), taking into account dimensional analysis, microstructural evaluation and mechanical tests which included Charpy-V impact, tensile and microhardness. A significant microstructural change and decrease, not only in the transition temperature, but also in the yield strength, occurred after induction bending. This reduction resulted in a tensile strength below the standard requirements. The subsequent tempering heat treatment applied to the curved section produced an increase in the yield strength to achieve the API 5L requirements for this class of steel.Copyright
Advanced Materials Research | 2006
A.R.B. Maia; C.R. Guinâncio; R.L. Germano; Paulo Rangel Rios; Ivani de Souza Bott
In this work, three Zr microalloyed steels with different levels of Zr were compared with plain C-Mn, Nb and Nb-Ti steels. Austenitic grain size was compared as a function of temperature for these steels. A qualitative assessment of the potential of Zr to delay austenite recrystallization, was also undertaken. Of course, the actual use of Zr depends on many considerations: cost, availability and behavior during steel refining among others but this preliminary assessment was encouraging. It showed that the addition of Zr was able to prevent grain growth at typical reheating temperatures, around 1200oC. Also, Zr was able to delay austenite recrystallization.
Welding International | 2015
Jorge Carlos Ferreira Jorge; Sérgio Maciel Faragasso; Luís Felipe Guimarães de Souza; Ivani de Souza Bott
Evaluation was performed of a weld metal with tensile strength higher than 860 MPa for welding R4 grade steel of standard W22 of the International Association of Classification Societies, Ltd. Multipass joints were welded with preheating at 200 and 250°C, using the coated electrode process with a 4.0-mm-diameter consumable, the basic composition of which was: C – 0.06%, Mn – 1.89% and Ni – 2.95%. After welding, mechanical and metallographic tests were performed on samples entirely removed from the metal deposited in conditions as-welded and after post-weld heat treatment performed at 600°C for 2 h. The results show that the weld metals obtained have mechanical properties suitable for all conditions of analysis, providing properties superior to the minimum required for welding R4 grade steel used on petroleum platform mooring equipment. The metallographic analysis enabled identification of the microstructure and explanation of the behaviour of the mechanical properties after post-weld heat treatment.
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Luís Felipe Guimarães de Souza
Centro Federal de Educação Tecnológica de Minas Gerais
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