6 research outputs found
Evaluaci贸n de la resistencia a corrosi贸n sobre tensi贸n y fragilizaci贸n por hidr贸geno de soldaduras circunferenciales de aceros API 5L X80 fabricados en Brasil
Resumen Este estudio eval煤a la susceptibilidad a corrosi贸n sobre tensi贸n (SSCC) y la fragilizaci贸n por hidr贸geno (HE), de soldaduras circunferenciales de acero API 5L-X80 producidos en Brasil. Ensayos de tracci贸n con baja velocidad de deformaci贸n (SSRT) y ensayos de permeaci贸n de hidr贸geno se realizaron a temperatura ambiente, en soluciones de tiosulfato de sodio, para simular diferentes ambientes 谩cidos. La susceptibilidad a la HE y potencialmente a SSCC se manifest贸 por la reducci贸n de la ductilidad en los ensayos SSRT y el aumento en los valores de corriente de permeaci贸n de hidr贸geno, para casi todas las uniones soldadas ensayadas. Se observ贸 mayor susceptibilidad en las soluciones m谩s 谩cidas (pH = 3,4), mientras que para las soluciones de ensayo menos 谩cidas (pH = 4,4) se observ贸 poca p茅rdida de ductilidad y la corriente de permeaci贸n de hidr贸geno se mantuvo en valores cercanos a cero, lo que indica poca o ninguna penetraci贸n de hidr贸geno a trav茅s del metal para los tiempos de ensayo utilizados. Este comportamiento fue atribuido a la disoluci贸n an贸dica del Fe junto con la fragilizaci贸n por hidr贸geno. Se observ贸 que el pH de la soluci贸n tiene mayor influencia que la concentraci贸n de H2S, en la susceptibilidad a SSCC y HE. Palabras clave: susceptibilidad, hidr贸geno, fragilizaci贸n, corrosi贸n bajo tensi贸n.Evaluation of the susceptibility to sulphide stress聽corrosion cracking and hydrogen embrittlement of API聽5L X80 girth welds steel manufactured in Brazil Abstract This study evaluates the susceptibility to sulphide stress corrosion cracking (SSCC) and hydrogen embrittlement (HE) of API 5L-X80 girth welds steel produced in Brazil. Tensile and low strain rate tests (SSRT) and hydrogen permeation tests were performed at room temperature in solutions of sodium thiosulfate, to simulate different acidic environments. The susceptibility to HE and potentially SSCC is manifested by the reduction in ductility in the SSRT tests and increased the values聽 of hydrogen permeation current for almost all welds tested. Increased susceptibility was observed in more acidic solutions (pH = 3.4), while for the test solutions less acidic (pH = 4.4) was observed little loss of ductility and hydrogen permeation current was maintained at values聽 close to zero, indicating little or no penetration of hydrogen through the metal for test times used. This behavior was attributed to the anodic dissolution of Fe with hydrogen embrittlement. It was observed that the pH of the solution has a greater influence than the concentration of H2S in the susceptibility to SSCC and HE. Keywords: susceptibility, hydrogen, embrittlement, stress corrosion cracking
Evaluaci贸n de la resistencia a corrosi贸n sobre tensi贸n y fragilizaci贸n por hidr贸geno de soldaduras circunferenciales de aceros API 5L X80 fabricados en Brasil
Resumen Este estudio eval煤a la susceptibilidad a corrosi贸n sobre tensi贸n (SSCC) y la fragilizaci贸n por hidr贸geno (HE), de soldaduras circunferenciales de acero API 5L-X80 producidos en Brasil. Ensayos de tracci贸n con baja velocidad de deformaci贸n (SSRT) y ensayos de permeaci贸n de hidr贸geno se realizaron a temperatura ambiente, en soluciones de tiosulfato de sodio, para simular diferentes ambientes 谩cidos. La susceptibilidad a la HE y potencialmente a SSCC se manifest贸 por la reducci贸n de la ductilidad en los ensayos SSRT y el aumento en los valores de corriente de permeaci贸n de hidr贸geno, para casi todas las uniones soldadas ensayadas. Se observ贸 mayor susceptibilidad en las soluciones m谩s 谩cidas (pH = 3,4), mientras que para las soluciones de ensayo menos 谩cidas (pH = 4,4) se observ贸 poca p茅rdida de ductilidad y la corriente de permeaci贸n de hidr贸geno se mantuvo en valores cercanos a cero, lo que indica poca o ninguna penetraci贸n de hidr贸geno a trav茅s del metal para los tiempos de ensayo utilizados. Este comportamiento fue atribuido a la disoluci贸n an贸dica del Fe junto con la fragilizaci贸n por hidr贸geno. Se observ贸 que el pH de la soluci贸n tiene mayor influencia que la concentraci贸n de H2S, en la susceptibilidad a SSCC y HE. Palabras clave: susceptibilidad, hidr贸geno, fragilizaci贸n, corrosi贸n bajo tensi贸n.Evaluation of the susceptibility to sulphide stress聽corrosion cracking and hydrogen embrittlement of API聽5L X80 girth welds steel manufactured in Brazil Abstract This study evaluates the susceptibility to sulphide stress corrosion cracking (SSCC) and hydrogen embrittlement (HE) of API 5L-X80 girth welds steel produced in Brazil. Tensile and low strain rate tests (SSRT) and hydrogen permeation tests were performed at room temperature in solutions of sodium thiosulfate, to simulate different acidic environments. The susceptibility to HE and potentially SSCC is manifested by the reduction in ductility in the SSRT tests and increased the values聽 of hydrogen permeation current for almost all welds tested. Increased susceptibility was observed in more acidic solutions (pH = 3.4), while for the test solutions less acidic (pH = 4.4) was observed little loss of ductility and hydrogen permeation current was maintained at values聽 close to zero, indicating little or no penetration of hydrogen through the metal for test times used. This behavior was attributed to the anodic dissolution of Fe with hydrogen embrittlement. It was observed that the pH of the solution has a greater influence than the concentration of H2S in the susceptibility to SSCC and HE. Keywords: susceptibility, hydrogen, embrittlement, stress corrosion cracking
LABORATORY INVESTIGATION OF ENVIRONMENTALLY INDUCED CRACKING OF API-X70 AND X80 PIPELINE STEELS
ABSTRACT Carbon steels, used in pipelines for the transport of oil and its derivatives, are frequently exposed to fluids. This can result in stress induced corrosion cracking (SCC) and/or hydrogen embrittlement (HE). The present paper evaluates the susceptibility of pipeline steels (API-X70 and API-X80) to SCC and HE, using a slow strain rate test (SSRT) based on the National Association of Corrosion Engineers' (NACE) norm and a traditional standard NACE test. The (SSRT) method used, employed a sodium thiosulphate solution to evaluate susceptibility to HE, thereby offering a simpler experimental procedure than the standard NACE test. The results confirm the efficacy of the sodium thiosulphate as an H 2 S -SCC susceptibility test solution when utilised in SSRT testing. Though no secondary cracks were detected in the materials investigated, both steels were observed to suffer a ductility loss upon exposure to this solution. In NACE type tests, the test pieces were subjected to constant loading at 80% of 蟽 y . Fracture did not occur for these samples
3D conductive monolithic carbons from pyrolyzed bamboo for microfluidic self-heating system
Bamboo, like wood, is a promising natural template for biobased devices that takes advantage of its hierarchical architecture, microarray channels, anisotropic mechanical and electrical properties. Herein we report a low heat thermal treatment (HTT, 700-1000 掳C) of natural bamboo specimens to obtain bamboo-based graphitic devices with thermoelectric and electrochemical properties. The preservation of the highly anisotropic architecture of three-dimensional carbon material (3D-CM) allowed adding specific thermoelectric and electrochemical properties depending on the HTT of the pristine specimens. High electric conductivity (蟽, 839 S/m) was observed at 1000 掳C showing a remarkable potential application as a bamboo-based working electrode. The bamboo annealed to 700 掳C showed higher resistivity (蟻, 0.15 惟 m, and 蟽, 6.6 S/m), thermal conductivity (1.77 W/m K), and thermal heating rate (1.0 掳C/s). The pyrolyzed biomass (B-700) was used as a 3D microfluidic heater to heat polar solvents (H2O and ethylene glycol) in flow mode up to their boiling points. A 2D carbon hotplate heater was built-up to warm solvent in batch mode. A complete chemical and physical characterization of the samples allowed us to determine structural and chemical compositions, cellulose crystalline structure phase transition to graphitic/turbostratic carbon, thermal and electrical conductivity of unprecedented bambootronics bio-devices
Desempenho de metal de solda adequado para soldagem de componentes de ancoragem
O presente trabalho apresenta os resultados de um programa de pesquisa cujo objetivo principal 茅 o desenvolvimento de consum铆veis adequados para a soldagem de componentes de ancoragem fabricados em a莽os de alta resist锚ncia. Ap贸s avalia莽茫o de diferentes composi莽玫es qu铆micas, com base no balan莽o de Mn e Ni 茅 feita uma an谩lise detalhada das propriedades mec芒nicas e microestruturais da composi莽茫o qu铆mica que propiciou os melhores resultados para permitir uma conclus茫o decisiva. Foram soldadas juntas pelo processo eletrodo revestido utilizando consum铆veis de 4,0 mm de di芒metro, com preaquecimento de 200 潞C, corrente cont铆nua, posi莽茫o plana e energia de soldagem nominal de 1,5 kJ / mm. Ap贸s a soldagem, foram realizados ensaios mec芒nicos (tens茫o, impacto Charpy-V, dureza) e metalogr谩ficos por microscopia 贸tica, microscopia eletr么nica de varredura e EBSD em amostras removidas integralmente do metal de solda, tanto na condi莽茫o de como soldado quanto ap贸s tratamento t茅rmico p贸s-soldagem (TTPS) realizado a 600 潞C. Os resultados mostram que os metais de solda obtiveram propriedades mec芒nicas satisfat贸rias ap贸s o TTPS, sendo adequados para aplica莽茫o em componentes de ancoragem de acordo com a especifica莽茫o IACS W22. Al茅m disso, observou-se que a tenacidade ao impacto experimentou uma melhoria com o aumento do tempo de TTPS, o que 茅 crucial para componentes com maiores espessuras. Palavras-chave: metal de solda, propriedades mec芒nicas, tratamento t茅rmico, componentes de ancorage