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Nos últimos anos, a indústria de O&G tem enfrentado um considerável desafio no que tange a obtenção de materiais que associem elevada resistência à corrosão às propriedades mecânicas para exploração dos poços das bacias do Pré-Sal. Estes poços apresentam elevadas concentrações de CO2, H2S e cloretos de forma que a resistência à corrosão é uma necessidade. De outro lado, as elevadas profundidades de exploração acopladas com a necessária produtividade têm indicado que a pressão de trabalho destes materiais tende a aumentar. O desafio atualmente reside na obtenção de materiais para fabricação de peças de grandes dimensões como conectores e cabeças de poços. Uma das soluções mais promissoras para a solução deste desafio é a liga UNS N06625, visto que esta liga já é utilizada na indústria de O&G em aplicações nas quais a elevada resistência à corrosão é associada com resistência mecânica. A liga UNS N06625 é tipicamente vista pelo mercado como uma liga monofásica austenítica devido ao uso mais frequente ser associado com peças de pequenas dimensões, barras e arames para soldas e revestimentos, tipicamente tratadas em acordo com as normas ASTM B446 e ASTM B564. A obtenção desta liga na condição monofásica está associada com facilidades associadas com o tratamento termomecânico de peças de pequenas dimensões que aquecem e resfriam com elevadas taxas possibilitando atingir elevado refino de grão em uma estrutura monofásica. O presente trabalho estudou de forma controlada o efeito do teor de ferro na microestrutura e propriedades da liga UNS N06625. Foram avaliados os estados bruto de forjamento, solubilizado e envelhecido de forma a determinar o efeito do teor de ferro no diagrama TTT da liga UNS N06626. Através deste trabalho foi possível se observar que a cinética de precipitação da fase delta e do carboneto do tipo M6C sofrem alterações com o aumento do teor de ferro de forma a reduzir o tempo para precipitação. Adicionalmente foi realizado um estudo do efeito de rampas de aquecimento no tratamento de solubilização, partindo-se do estado conformado a quente, indicando que há um efeito sinérgico entre o encruamento e a precipitação de fase delta durante o aquecimento para o patamar de solubilização resultando sem severa alteração das resistências à corrosão e mecânica da liga. / Lately, the O&G industry has faced a big challenge to find materials that couple the high corrosion resistance with the desired mechanical resistance, for application in the oil and gas wells of the Pre-salt basins. This wells present high CO2, H2S and chlorine contents and the high corrosion resistance is essential. On the other hand, the high exploration depth associated with the necessary productivity has signalized that the working pressure of the materials will increase. Todays challenge is to obtain materials to manufacture large section parts as well heads and connectors. One of the more promising solutions to this challenge is the UNS N06625 alloy, as this alloy is already applied on the O&G industry in applications were the corrosion resistance must be coupled with the mechanical resistance. UNS N06625 alloy is typically understood by the market as an austenitic monophasic alloy, due to the more frequent use to be related with small section parts as bars, rods and wires for coating and welding, usually heat treated in accord with ASTM B446 and ASTM B564. The manufacture of this alloy in the monophasic condition is related to the conveniences of the thermomechanical treatment of small section parts that heat and cool at high rates, which allows high grain refinement and the monophasic structure. The present work has studied in a controlled way the iron content effect on the microstructure and properties of UNS N06625 alloy. UNS N06625 alloy was evaluated in the as forged, solution annealed and aged conditions in order to determine the effect of the iron content on the TTT diagram of UNS N06625 alloy. Through this work it was possible to verify that the kinetic of precipitation of delta phase and M6C carbide present some changes with the increase of the iron content by the reduction of the time needed to precipitation. Additionally the effect of the heating rate in the solution annealing heat treatment was studied, beginning in the as hot forged/rolled conditions which indicate that there is a synergic effect of the hardening and the delta phase precipitation during the heating of the material from the room temperature to the solution annealing temperature resulting in severe changes in the corrosion and mechanical resistances of the alloy.

Nos últimos anos, a indústria de O&G tem enfrentado um considerável desafio no que tange a obtenção de materiais que associem elevada resistência à corrosão às propriedades mecânicas para exploração dos poços das bacias do Pré-Sal. Estes poços apresentam elevadas concentrações de CO2, H2S e cloretos de forma que a resistência à corrosão é uma necessidade. De outro lado, as elevadas profundidades de exploração acopladas com a necessária produtividade têm indicado que a pressão de trabalho destes materiais tende a aumentar. O desafio atualmente reside na obtenção de materiais para fabricação de peças de grandes dimensões como conectores e cabeças de poços. Uma das soluções mais promissoras para a solução deste desafio é a liga UNS N06625, visto que esta liga já é utilizada na indústria de O&G em aplicações nas quais a elevada resistência à corrosão é associada com resistência mecânica. A liga UNS N06625 é tipicamente vista pelo mercado como uma liga monofásica austenítica devido ao uso mais frequente ser associado com peças de pequenas dimensões, barras e arames para soldas e revestimentos, tipicamente tratadas em acordo com as normas ASTM B446 e ASTM B564. A obtenção desta liga na condição monofásica está associada com facilidades associadas com o tratamento termomecânico de peças de pequenas dimensões que aquecem e resfriam com elevadas taxas possibilitando atingir elevado refino de grão em uma estrutura monofásica. O presente trabalho estudou de forma controlada o efeito do teor de ferro na microestrutura e propriedades da liga UNS N06625. Foram avaliados os estados bruto de forjamento, solubilizado e envelhecido de forma a determinar o efeito do teor de ferro no diagrama TTT da liga UNS N06626. Através deste trabalho foi possível se observar que a cinética de precipitação da fase delta e do carboneto do tipo M6C sofrem alterações com o aumento do teor de ferro de forma a reduzir o tempo para precipitação. Adicionalmente foi realizado um estudo do efeito de rampas de aquecimento no tratamento de solubilização, partindo-se do estado conformado a quente, indicando que há um efeito sinérgico entre o encruamento e a precipitação de fase delta durante o aquecimento para o patamar de solubilização resultando sem severa alteração das resistências à corrosão e mecânica da liga. / Lately, the O&G industry has faced a big challenge to find materials that couple the high corrosion resistance with the desired mechanical resistance, for application in the oil and gas wells of the Pre-salt basins. This wells present high CO2, H2S and chlorine contents and the high corrosion resistance is essential. On the other hand, the high exploration depth associated with the necessary productivity has signalized that the working pressure of the materials will increase. Todays challenge is to obtain materials to manufacture large section parts as well heads and connectors. One of the more promising solutions to this challenge is the UNS N06625 alloy, as this alloy is already applied on the O&G industry in applications were the corrosion resistance must be coupled with the mechanical resistance. UNS N06625 alloy is typically understood by the market as an austenitic monophasic alloy, due to the more frequent use to be related with small section parts as bars, rods and wires for coating and welding, usually heat treated in accord with ASTM B446 and ASTM B564. The manufacture of this alloy in the monophasic condition is related to the conveniences of the thermomechanical treatment of small section parts that heat and cool at high rates, which allows high grain refinement and the monophasic structure. The present work has studied in a controlled way the iron content effect on the microstructure and properties of UNS N06625 alloy. UNS N06625 alloy was evaluated in the as forged, solution annealed and aged conditions in order to determine the effect of the iron content on the TTT diagram of UNS N06625 alloy. Through this work it was possible to verify that the kinetic of precipitation of delta phase and M6C carbide present some changes with the increase of the iron content by the reduction of the time needed to precipitation. Additionally the effect of the heating rate in the solution annealing heat treatment was studied, beginning in the as hot forged/rolled conditions which indicate that there is a synergic effect of the hardening and the delta phase precipitation during the heating of the material from the room temperature to the solution annealing temperature resulting in severe changes in the corrosion and mechanical resistances of the alloy.

Este trabalho estuda as fases presentes na solda de Inconel 625 utilizadas para unir tubos de uma serpentina de forno de uma refinaria de petrÃleo, fabricada com material de aÃo liga tipo 9Cr-1Mo e revestida internamente com alumÃnio. Para a realizaÃÃo do estudo, foi fabricado um corpo dee prova em conformidade com os procedimentos de fabricaÃÃo da serpentina tubular do forno. Amostras da junta soldada foram cortadas e submetidas a ensaios de microdureza, estudos da variaÃÃo da composiÃÃo quÃmica pelo EDS, avaliaÃÃo de fases por difraÃÃo de raios-X e pela tÃcnica por difraÃÃo de elÃtrons retroespalhados (EBSD), assim como detalhes da microestrutura foram observados por microscopia Ãtica e microscopia eletrÃnica de varredura. Os resultados mostram a provÃvel presenÃa de carbonetos de Ti, Nb e fase Laves na solda de Inconel 625. A quantidade de fase Laves à maior no revestimento de Inconel do que no passe raiz. Foram observados tambÃm descontinuidades e defeitos. Um destes defeitos estava localizado na interface entre o Inconel 625 e o primeiro passe com eletrodo AWS E-505, em regiÃo provavelmente rica em precipitados de fase Laves. Os resultados indicam a necessidade de uma melhor avaliaÃÃo do processo de soldagem, incluindo um estudo do comportamento do Inconel 625 na temperatura de operaÃÃo do forno entre 500 e 700ÂC. / This work studies the phases present in Inconel 625 weld used to join tubes of a coil of furnace oil refinery, made ​​of alloy steel material type 9Cr-1mo and lined with aluminum. For the study was made ​​a test dee body in accordance with the manufacturing procedures of the tubular coil of the furnace. Samples of the weld were cut and subjected to microhardness tests, studies of variation of chemical composition by SDS evaluation phase diffraction X-ray diffraction technique, and backscattered electrons (EBSD) as well as details of the microstructure was observed by optical microscopy and scanning electron microscopy. The results show the probable presence of carbides of Ti, Nb and Laves phase in Inconel 625 weld. The amount of Laves phase in the coating is greater than Inconel the root pass. It was also observed discontinuities and defects. One of these defects was located at the interface between the Inconel 625 and the first electrode pass AWS E-505 in rich region probably Laves phase precipitate. The results indicate the need for better assessment of the welding process, including a study of the behavior of Inconel 625 in the temperature of the furnace between 500  and 700  C.

In this research, controlled Waspaloy microstructures were produced with the objective of studying microstructural evolution in this alloy via electrically-based ac/dc non-destructive techniques. Correlations were developed between electrical measurements and alternate characterization techniques such as Ultra Small Angle X-ray Scattering (USAXS), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) to gain a complete understanding of the microstructural transformations and the associated mechanisms. Three different sets of controlled microstructures were produced in this research. In Set I microstructures, matrix (gamma) grain sizes of 13, 52 and 89 micrometers were obtained after solution-treatments at 1045 and 176;C, 1090 and 176;C and 1145 and 176;C respectively. A vacancy stabilization treatment at 1045 and 176;C followed after which, the specimens were aged at 800 and 176;C for times ranging from 0.1 hrs to 100 hrs to vary the gamma prime precipitate size distribution. In Sets II and III, the solution-treatment was only conducted at 1145 and 176;C, with the stabilization treatment conducted only in Set II. Subsequently, aging experiments were conducted at 725 and 176;C (or 700 and 176;C in Set II), 800 and 176;C and 875 and 176;C for times up to 100 hrs. DC four-point probe resistivity of specimens increased to a maximum upon initial aging from the solution-treated condition and showed a decreasing trend thereafter with successive aging. This, in addition to complementary evidence from SEM and USAXS, led to the conclusion that gamma prime nucleation-growth was complete by the time the resistivity maximum was observed. Resistivity variations that ensued upon successive aging after the maximum were attributed to microstructural/compositional changes due to gamma prime coarsening. The height of the maximum decreased drastically with increase in aging temperature from 725 and 176;C to 800 and 176;C, while the resistivity did not increase from the solution-treated condition upon aging at 875 and 176; C. Coarsening studies based on USAXS analysis indicated an LSW type volume diffusion mechanism of coarsening in Waspaloy, with an average coarsening rate constant of 3.25x10-29 [m3/sec] for Set I specimens aged at 800 and 176;C. Analytical and Finite Element (FE) models of two-probe impedance and dc four-point probe resistivity methods were developed to gain insight into the measured response and the accurate determination of material properties. AFM-based localized electrical examination of sub-grain Waspaloy microstructures was successfully conducted using electrostatic force microscopy (EFM), scanning Kelvin probe microscopy (SKPM) and current-AFM (I-AFM) electrical modes. I-AFM experiments revealed that the conductivity of the gamma prime phase was lower than that of the gamma phase.

Thesis (Ph. D.)--Ohio State University, 2009. / Title from first page of PDF file. Includes bibliographical references (p. 229-238).

No description available.

Directionally solidified (DS) nickel-base superalloys are used in high temperature gas turbine engines because of their high yield strength at extreme temperatures and strong low cycle fatigue (LCF) and creep resistance. Costly inspecting, servicing, and replacing of damaged components has precipitated much interest in developing models to better predict service life. Turbine blade life modeling is complicated by the presence of notches, dwells, high temperatures and temperature gradients, and highly anisotropic material behavior. This work seeks to develop approaches for predicting the life of hot sections of gas turbines blade material CM247LC DS subjected to LCF, dwells, and stress concentrations while taking into consideration orientation and notch effects. Experiments were conducted on an axial servo-hydraulic MTS® testing machine. High temperature LCF tests were performed on smooth and notched round-bar specimens in both longitudinal and transverse orientations with and without dwells. Experimental results were used to develop and validate an analytical life prediction model. An analytical model based on a multiaxial Neuber approach predicts the local stress-strain response at a notch and other geometric stress concentrations. This approach captures anisotropy through a multiaxial generalization of the Ramberg-Osgood relation using a Hill's type criterion. The elastic notch response is determined using an anisotropic elastic finite element analysis (FEA) of the notch. The limitations of the simpler analytical life-modeling method are discussed in light of FEA using an anisotropic elastic-crystal viscoplastic material model. This life-modeling method provides a quick alternative to time demanding elastic-plastic FEA allowing engineers more design iterations to improve reliability and service life.

The focus of this literary study was additive manufacturing (AM) and the purpose was to find general trends for selected materials that have been additively manufactured and compare them to results from other reviews. The raw materials studied were stainless steels 316L, 17-4 PH, 15-5 PH and 420, as well as tool steel H13 and nickel alloys 625, 718 and Hastelloy X.The AM techniques studied were selective laser melting (SLM), electron beam melting (EBM) and binder jetting (BJG).  A total of 69 articles have been studied to fulfill the purpose above. The articles were used to write a summary of the techniques, compare them to each other and to conventional methods. They were also used to create a database to compile information on mechanical properties, microstructure and process parameters. Based on the database mechanical properties for SLM tend to be higher compared to EBM. This however varied somewhat depending on the processed material. Furthermore the yield and tensile strength obtained from the database for SLM seemed to be higher compared to the values in review articles for almost all materials. Unfortunately not enough values were found for BJG to compare it to SLM and EBM.AM seems to produce weaker, equal and superior products compared to conventional methods. However due to the limited nature of the project and the research found no conclusions can be drawn about any trends, how to achieve the different results or how parameters affect the finished product. To be able to say anything with more certainty more research has to be done. Not only in general concerning the AM techniques, but more studying of existing articles is needed. Finally a standardization on how to reference properties and process parameters is necessary. Currently it is very difficult to compare results or draw conclusions due to different designations, units and a lot of missing essential information.

The focus of this literary study was additive manufacturing (AM) and the purpose was to find general trends for selected materials that have been additively manufactured and compare them to results from other reviews. The raw materials studied were stainless steels 316L, 17-4 PH, 15-5 PH and 420, as well as tool steel H13 and nickel alloys 625, 718 and Hastelloy X. The AM techniques studied were selective laser melting (SLM), electron beam melting (EBM) and binder jetting (BJG).  A total of 69 articles have been studied to fulfill the purpose above. The articles were used to write a summary of the techniques, compare them to each other and to conventional methods. They were also used to create a database to compile information on mechanical properties, microstructure and process parameters. Based on the database mechanical properties for SLM tend to be higher compared to EBM. This however varied somewhat depending on the processed material. Furthermore the yield and tensile strength obtained from the database for SLM seemed to be higher compared to the values in review articles for almost all materials. Unfortunately not enough values were found for BJG to compare it to SLM and EBM.AM seems to produce weaker, equal and superior products compared to conventional methods. However due to the limited nature of the project and the research found no conclusions can be drawn about any trends, how to achieve the different results or how parameters affect the finished product. To be able to say anything with more certainty more research has to be done. Not only in general concerning the AM techniques, but more studying of existing articles is needed. Finally a standardization on how to reference properties and process parameters is necessary. Currently it is very difficult to compare results or draw conclusions due to different designations, units and a lot of missing essential information.