Augusto Di Gianfrancesco - Academia.edu (original) (raw)
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Papers by Augusto Di Gianfrancesco
Latin American applied research Pesquisa aplicada latino americana = InvestigacioĢn aplicada latinoamericana
International Journal of Pressure Vessels and Piping, 2009
The metallurgical background of advanced ferritic steels must be considered during every stage of... more The metallurgical background of advanced ferritic steels must be considered during every stage of fabrication, including forming operations, such as cold bending, because they can negatively affect the high-temperature properties of the material when not performed properly. In this work, the results of a broad cold bending program carried out on ASTM Grades T23, T91 and T92 tubes in the range 1.0 R/OD 4.5 are presented; the industrial window for a safe and repeatable cold bending of 9%Cr tubes was defined: ovalisation and thickness variation were measured after the bending; the microstructure, the hardness values and the mechanical properties at extrados and intrados positions were investigated and compared with properties of unbent materials. Optimum post bending heat treatment of most severe bends was defined. This paper aims to integrate the International Codes for cold bending with recommendations for proper post bending heat treatments, in order to obtain a final component with the desired microstructure, cold workability and mechanical properties. Recommendations for the post bending heat treatment were formulated and compared with the prescriptions given by the relevant International Codes and Standards. Creep properties of large cold bends were also assessed by means of specimens directly machined from extrados and intrados portions of real bends. Both extrados and intrados areas of T23, T91 and T92 bends exhibited a creep resistance within the lower scatter band of base material isothermal curve. The creep-rupture ductility of the intrados was measured higher than that of the extrados.
Engineering & Technology Reference, 2012
Procedia Engineering, 2013
The 9%Cr steel grades were developed in the last 25 year in order to favourite the target of the ... more The 9%Cr steel grades were developed in the last 25 year in order to favourite the target of the improvement of the steam temperature and pressure necessary to increase the efficiency of the modern coal fired power plant for electricity production. Now a relevant experience in testing and service conditions has been generated and it is possible to produce consistent assessments of the mechanical and creep behaviours for long term application. On the other hand the further trials to increase the Chromium content to improve the corrosion-oxidation behaviours of the 9%Cr grades, despite the very promising short term properties, generate unpredicted premature failure after long term exposure. This failure was identified in the instability of the compositions with the appearance of Z-phase, with consequent drop down of the creep behaviours below their parent 9%Cr grades. This paper summarize the maturated knowledge in the field of the microstructural evolution of the 9-12%Cr steels, as well as, the current status of development of these steel grades.
Materials for Ultra-Supercritical and Advanced Ultra-Supercritical Power Plants provides research... more Materials for Ultra-Supercritical and Advanced Ultra-Supercritical Power Plants provides researchers in academia and industry with an essential overview of the stronger high-temperature materials required for key process components, such as membrane wall tubes, high-pressure steam piping and headers, superheater tubes, forged rotors, cast components, and bolting and blading for steam turbines in USC power plants. Advanced materials for future advanced ultra-supercritical power plants, such as superalloys, new martensitic and austenitic steels, are also addressed. Chapters on international research directions complete the volume. The transition from conventional subcritical to supercritical thermal power plants greatly increased power generation efficiency. Now the introductions of the ultra-supercritical (USC) and, in the near future, advanced ultra-supercritical (A-USC) designs are further efforts to reduce fossil fuel consumption in power plants and the associated carbon dioxide e...
Journal of Material Science & Engineering
Volume 9: Eighth International Conference on Creep and Fatigue at Elevated Temperatures, 2007
International Journal of Pressure Vessels and Piping, 2010
The steam parameters in the new high efficiency fossil fuel power plants are continuously increas... more The steam parameters in the new high efficiency fossil fuel power plants are continuously increasing, requiring new advanced materials with enhanced creep strength able to operate on the most severe temperature and pressure conditions. For super-heater and re-heater applications, TEMPALOY AA-1 steel, an evolution of 18Cr10NiNbTi alloy, has been developed through the addition of 3%Cu and B, significantly enhancing the creep resistance, while offering typical corrosion properties of 18%Cr steels. This paper describes Tenaris' tubular products in the field of austenitic grades for applications in Ultra Super Critical power plants: the production route and the main microstructural and mechanical properties of TEMPALOY AA-1 and TEMPALOY A-3 steels, including the effect of shot blasting on steam-oxidation resistance, their creeperupture properties and their microstructural evolution during temperature exposure are presented.
Latin American applied research Pesquisa aplicada latino americana = InvestigacioĢn aplicada latinoamericana
International Journal of Pressure Vessels and Piping, 2009
The metallurgical background of advanced ferritic steels must be considered during every stage of... more The metallurgical background of advanced ferritic steels must be considered during every stage of fabrication, including forming operations, such as cold bending, because they can negatively affect the high-temperature properties of the material when not performed properly. In this work, the results of a broad cold bending program carried out on ASTM Grades T23, T91 and T92 tubes in the range 1.0 R/OD 4.5 are presented; the industrial window for a safe and repeatable cold bending of 9%Cr tubes was defined: ovalisation and thickness variation were measured after the bending; the microstructure, the hardness values and the mechanical properties at extrados and intrados positions were investigated and compared with properties of unbent materials. Optimum post bending heat treatment of most severe bends was defined. This paper aims to integrate the International Codes for cold bending with recommendations for proper post bending heat treatments, in order to obtain a final component with the desired microstructure, cold workability and mechanical properties. Recommendations for the post bending heat treatment were formulated and compared with the prescriptions given by the relevant International Codes and Standards. Creep properties of large cold bends were also assessed by means of specimens directly machined from extrados and intrados portions of real bends. Both extrados and intrados areas of T23, T91 and T92 bends exhibited a creep resistance within the lower scatter band of base material isothermal curve. The creep-rupture ductility of the intrados was measured higher than that of the extrados.
Engineering & Technology Reference, 2012
Procedia Engineering, 2013
The 9%Cr steel grades were developed in the last 25 year in order to favourite the target of the ... more The 9%Cr steel grades were developed in the last 25 year in order to favourite the target of the improvement of the steam temperature and pressure necessary to increase the efficiency of the modern coal fired power plant for electricity production. Now a relevant experience in testing and service conditions has been generated and it is possible to produce consistent assessments of the mechanical and creep behaviours for long term application. On the other hand the further trials to increase the Chromium content to improve the corrosion-oxidation behaviours of the 9%Cr grades, despite the very promising short term properties, generate unpredicted premature failure after long term exposure. This failure was identified in the instability of the compositions with the appearance of Z-phase, with consequent drop down of the creep behaviours below their parent 9%Cr grades. This paper summarize the maturated knowledge in the field of the microstructural evolution of the 9-12%Cr steels, as well as, the current status of development of these steel grades.
Materials for Ultra-Supercritical and Advanced Ultra-Supercritical Power Plants provides research... more Materials for Ultra-Supercritical and Advanced Ultra-Supercritical Power Plants provides researchers in academia and industry with an essential overview of the stronger high-temperature materials required for key process components, such as membrane wall tubes, high-pressure steam piping and headers, superheater tubes, forged rotors, cast components, and bolting and blading for steam turbines in USC power plants. Advanced materials for future advanced ultra-supercritical power plants, such as superalloys, new martensitic and austenitic steels, are also addressed. Chapters on international research directions complete the volume. The transition from conventional subcritical to supercritical thermal power plants greatly increased power generation efficiency. Now the introductions of the ultra-supercritical (USC) and, in the near future, advanced ultra-supercritical (A-USC) designs are further efforts to reduce fossil fuel consumption in power plants and the associated carbon dioxide e...
Journal of Material Science & Engineering
Volume 9: Eighth International Conference on Creep and Fatigue at Elevated Temperatures, 2007
International Journal of Pressure Vessels and Piping, 2010
The steam parameters in the new high efficiency fossil fuel power plants are continuously increas... more The steam parameters in the new high efficiency fossil fuel power plants are continuously increasing, requiring new advanced materials with enhanced creep strength able to operate on the most severe temperature and pressure conditions. For super-heater and re-heater applications, TEMPALOY AA-1 steel, an evolution of 18Cr10NiNbTi alloy, has been developed through the addition of 3%Cu and B, significantly enhancing the creep resistance, while offering typical corrosion properties of 18%Cr steels. This paper describes Tenaris' tubular products in the field of austenitic grades for applications in Ultra Super Critical power plants: the production route and the main microstructural and mechanical properties of TEMPALOY AA-1 and TEMPALOY A-3 steels, including the effect of shot blasting on steam-oxidation resistance, their creeperupture properties and their microstructural evolution during temperature exposure are presented.