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gas composition
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Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 783-794, October 21–24, 2019,
... on following three factors: deposit chemistry, gas constituents and metal alloy (or bond coating/thermal barrier coating) composition. This paper reports the activities involved in establishing modeling and simulation followed by testing/characterization methodologies in relevant environments to understand...
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Modern gas turbines are operated with fuels that are very clean and within the allowances permitted by fuel specifications. However, the fuels that are being considered contain vanadium, sulfur, sodium and calcium species that could significantly contribute to the degradation of components in hot gas flow path. The main potential risk of material degradation from these fuels is “hot corrosion” due to the contaminants listed above combined with alkali metal salts from ambient air. Depending on the temperature regime hot corrosion can damage both TBC coatings and bond coat/substrate materials. Deposit-induced or hot corrosion has been defined as “accelerated oxidation of materials at elevated temperatures induced by a thin film of fused salt deposit”. For the initiation of hot corrosion, deposition of the corrosive species, e.g. vanadates or sulfates, is necessary. In addition to the thermodynamic stability, the condensation of the corrosive species on the blade/vane material is necessary to first initiate and then propagate hot corrosion. Operating temperatures and pressures both influence the hot corrosion damage. The temperature ranges over which the hot corrosion occurs depend strongly on following three factors: deposit chemistry, gas constituents and metal alloy (or bond coating/thermal barrier coating) composition. This paper reports the activities involved in establishing modeling and simulation followed by testing/characterization methodologies in relevant environments to understand the degradation mechanisms essential to assess the localized risk for fuel flexible operation. An assessment of component operating conditions and gas compositions throughout the hot gas paths of the gas turbines, along with statistical materials performance evaluations of metal losses for particular materials and exposure conditions, are being combined to develop and validate life prediction methods to assess component integrity and deposition/oxidation/corrosion kinetics.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 892-902, October 22–25, 2013,
.... In order to understand the role of substrate composition on corrosion, a combination of commercial and model alloys were investigated with synthetic coal ash and gas compositions simulating air- and oxyfiring environments. Exposure temperatures ranged from 600°-800°C to cover current operating temperatures...
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Using oxygen, rather than air, in coal-fired boilers has been studied for several years as a strategy to reduce NOx and concentrate CO 2 for capture. In combination with flue gas recirculation, higher levels of CO 2 are expected but increased H 2 O and SO 2 levels also may occur. In order to understand the role of substrate composition on corrosion, a combination of commercial and model alloys were investigated with synthetic coal ash and gas compositions simulating air- and oxyfiring environments. Exposure temperatures ranged from 600°-800°C to cover current operating temperatures up to advanced ultrasupercritical conditions. Using 500h exposures, no consistent negative effect was found for switching to the oxy-firing environment with the same synthetic ash. For model Fe-Cr alloys, 30%Cr was needed to form a thin protective reaction product across this temperature range. Among the commercial stainless steels, 310-type stainless steel showed low reaction rates with the maximum attack at 650°C. At higher temperatures, the depth of attack on Fe-base type 310 stainless steel was less than for Ni-base alloy 740. Initially, this difference was attributed to the Al and Ti additions in alloy 740. However, cast and hot rolled model Ni-18Cr and -22Cr alloys with various Al and Ti additions showed decreased metal loss with increasing Al and Ti additions in the oxy-firing environment at 700° and 800°C. As expected, metal loss was very sensitive to Cr content. A second set of model alloys also examined the effect of Co and Mo.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 360-370, October 22–25, 2013,
... contents to facilitate carbon capture and sequestration. To investigate the effects of changes in the gas composition on thermal barrier coating (TBC) lifetime, furnace cycling tests (1h cycles) were performed in air with 10, 50 and 90 vol.% water vapor and in CO 2 -10%H 2 O and compared to prior results...
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While the water vapor content of the combustion gas in natural gas-fired land based turbines is ~10%, it can be 20-85% with coal-derived (syngas or H 2 ) fuels or innovative turbine concepts for more efficient carbon capture. Additional concepts envisage working fluids with high CO 2 contents to facilitate carbon capture and sequestration. To investigate the effects of changes in the gas composition on thermal barrier coating (TBC) lifetime, furnace cycling tests (1h cycles) were performed in air with 10, 50 and 90 vol.% water vapor and in CO 2 -10%H 2 O and compared to prior results in dry air or O 2 . Two types of TBCs were investigated: (1) diffusion bond coatings (Pt diffusion or simple or Pt-modified aluminide) with commercially vapor-deposited yttria-stabilized zirconia (YSZ) top coatings on second-generation superalloy N5 and N515 substrates and (2) high velocity oxygen fuel (HVOF) sprayed MCrAlYHfSi bond coatings with air-plasma sprayed YSZ top coatings on superalloy X4 or 1483 substrates. In both cases, a 20-50% decrease in coating lifetime was observed with the addition of water vapor for all but the Pt diffusion coatings which were unaffected by the environment. However, the higher water vapor contents in air did not further decrease the coating lifetime. Initial results for similar diffusion bond coatings in CO 2 -10%H 2 O do not show a significant decrease in lifetime due to the addition of CO 2 . Characterization of the failed coating microstructures showed only minor effects of water vapor and CO 2 additions that do not appear to account for the observed changes in lifetime. The current 50°-100°C de-rating of syngas-fired turbines is unlikely to be related to the presence of higher water vapor in the exhaust.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 255-267, August 31–September 3, 2010,
... that are accurate to ±1µm in order to discern differences in corrosion rates. Cranfield University used their high temperature burner rig for longer duration corrosion testing (up to 1000 hours) using a range of synthetic deposits and gas environments. The deposit and gas compositions were developed based...
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This paper outlines a comprehensive UK-based research project (2007-2010) focused on developing fireside corrosion models for heat exchangers in ultra-supercritical plants. The study evaluates both conventional materials like T22 and advanced materials such as Super 304H, examining their behavior under various test environments with metal skin temperatures ranging from 425°C to 680°C. The research aims to generate high-quality data on corrosion behavior for materials used in both furnace and convection sections, ultimately producing reliable corrosion prediction models for boiler tube materials operating under demanding conditions. The project addresses some limitations of existing models for these new service conditions and provides a brief review of the fuels and test environments used in the program. Although modeling is still limited, preliminary results have been presented, focusing on predicting fireside corrosion rates for furnace walls, superheaters, and reheaters under various service environments. These environments include those created by oxyfuel operation, coal-biomass co-firing, and more traditional coal firing.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 998-1003, October 21–24, 2019,
... with the specimens was placed in the test zone. Then, the autoclave was sealed followed by temperature and pressure increase to target testing conditions. The equipment schematics and detailed procedures are described in a previous wok by the authors [7]. Meanwhile, the gas compositions of both CO2 grades used...
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The effect of gas impurities on corrosion behavior of candidate Fe- and Ni-base alloys (SS 316LN, Alloy 800HT, Alloy 600) in high temperature CO 2 environment was investigated in consideration of actual S-CO 2 cycle applications. Preliminary testing in research and industrial grade S-CO 2 at 600 °C (20 MPa) for 1000 h showed that oxidation rates were significantly reduced in industrial-grade S-CO 2 environment. Meanwhile, controlled tests with individual impurity additions such as CH 4 , CO, and O 2 in research-grade CO 2 were performed. The results indicated that CH 4 and CO additions did not seem to significantly affect oxidation rates. On the other hand, O 2 addition resulted in lower weight gains for all alloys, suggesting that O 2 may be primarily affecting corrosion behavior.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 863-880, October 22–25, 2013,
... the combustion environments adjacent to the superheaters and reheaters of coal-fired boilers to be characterized under both air and oxy-firing conditions. The gas and deposit compositions were then simulated in a series of 1000-hour laboratory corrosion tests in which the corrosion performance of different...
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A combined pilot-scale combustion test and long-term laboratory study investigated the impact of oxy-firing on corrosion in coal-fired boilers. Four coals were burned under both air and oxy-firing conditions with identical heat input, with oxy-firing using flue gas recirculation unlike air-firing. Despite higher SO 2 and HCl concentrations in oxy-firing, laboratory tests showed no increase in corrosion rates compared to air-firing. This is attributed to several factors: (1) Reduced diffusion: High CO 2 in oxy-firing densified the gas phase, leading to slower diffusion of corrosive species within the deposit. (2) Lower initial sulfate: Oxy-fired deposits initially contained less sulfate, a key hot corrosion culprit, due to the presence of carbonate. (3) Reduced basicity: CO 2 and HCl reduced the basicity of sulfate melts, leading to decreased dissolution of metal oxides and mitigating hot corrosion. (4) Limited carbonate/chloride formation: The formation of less corrosive carbonate and chloride solutes was restricted by low O 2 and SO 3 near the metal surface. These findings suggest that oxy-firing may not pose a greater corrosion risk than air-firing for boiler materials.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 224-234, October 11–14, 2016,
... corrosion test is shown in Table 3[7]. The top surfaces of specimens were covered with synthetic ash, and placed on a tray in a test furnace with a quartz chamber, and then simulated coal combustion gas was supplied into the chamber. The gas composition was simulated combustion gas from high sulfur coal...
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Recently, a γ’ precipitation strengthened Ni-base superalloy, USC141, was developed for 700°C class A-USC boiler tubes as well as turbine blades. In boiler tube application, the creep rupture strength of USC141 was much higher than that of Alloy617, and the 105 hours’ creep rupture strength of USC141 was estimated to be about 180MPa at 700°C. This is because fine γ’ particles precipitate in austenite grains and some kinds of intermetallic compounds and carbides precipitate along austenite grain boundaries during creep tests. Good coal ash corrosion resistance is also required for tubes at around 700°C. It is known that coal ash corrosion resistance depends on the contents of Cr and Mo in Ni-base superalloys. Therefore the effect of Cr and Mo contents in USC141 on coal ash corrosion resistance, tensile properties, and creep rupture strengths were investigated. As a result, the modified USC141 containing not less than 23% Cr and not more than 7% Mo showed better hot corrosion resistance than the original USC141. This modified alloy also showed almost the same mechanical properties as the original one. Furthermore the trial production of the modified USC141 tubes is now in progress.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 1388-1396, October 22–25, 2013,
... thickness at the bottom of the rib is 5.7mm. Sample panel welding employed Alloy 622 filler metal wire measuring 1.2mm in diameter. Table 1 shows the chemical composition of the Alloy 622 filler wire used to produce the weld overlay samples in this study. A gas shielded metal arc welding (GMAW) overlay...
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Recently, boiler waterwall tube damage such as fireside corrosion and circumferential cracking in low NOx environments has become a serious issue in Japan, despite the typical use of relatively lower sulfur content coal is typically being used than in US. Thermal spray coating has been the most popular method for tube protection in Japan, and thermal spray coated tubes have been used for this purpose. However, extensive damage to thermal spray coating tubes from cracking and exfoliation has been recently experienced. It has been reported that the thermal fluctuations occurring due to operational changes create alternating stress, leading to cracking and exfoliation of the thermal sprayed thin coating. Corrosion-resistant weld overlays, such as Type 309 stainless steel (in sub-critical boilers) and Alloy 622 (in sub-critical and super-critical boilers), are commonly used to protect boiler tubes from corrosion in low NOx coal fired boilers in U.S. In order to develop a fundamental understanding of the high temperature corrosive behavior of Alloy 622 weld overlay, gaseous corrosion testing and certain mechanical tests for consideration of long-term aging were undertaken. After four years of service in the low NOx combustion environment of a coal fired supercritical boiler, field tests on Alloy 622 weld overlay panels are in continuation. This paper describes the field test behavior of Alloy 622 weld overlay panels installed in a Japanese supercritical boiler, the laboratory results of weight loss corrosion testing, and the results of cyclic bend tests with overlay welded tubes related to aging.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 1014-1023, October 21–24, 2019,
... EXPOSURES The use of laboratory exposures enables key degradation parameters (e.g., gas composition, deposit composition and flux, metal temperature and time) to be systematically varied and closely controlled. This has enabled the development of a much better understanding of the effects of these variables...
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The combustion of coal and biomass fuels in power plants generates deposits on the surfaces of superheater / reheater tubes that can lead to fireside corrosion. This type of materials degradation can limit the lives of such tubes in the long term, and better methods are needed to produce predictive models for such damage. This paper reports on four different approaches that are being investigated to tackle the challenge of modelling fireside corrosion damage on superheaters / reheaters: (a) CFD models to predict deposition onto tube surfaces; (b) generation of a database of available fireside corrosion data; (c) development of mechanistic and statistically based models of fireside corrosion from laboratory exposures and dimensional metrology; (d) statistical analysis of plant derived fireside corrosion datasets using multi-variable statistical techniques, such as Partial Least Squares Regression (PLSR). An improved understanding of the factors that influence fireside corrosion is resulting from the use of a combination of these different approaches to develop a suite of models for fireside corrosion damage.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 310-317, October 11–14, 2016,
.... The ash composition (wt%) was 5% Na2SO4, 5% K2SO4, 30% Fe2O3, 30% Al2O3 and 30% SiO2 and the gas composition was 0.25% SO2, 3.5% O2, 15% CO2 314 and balance of N2. The samples were covered by a definite amount of ashes in an ethyl alchohol suspension. The ashes were renewed every 100 hours for the first...
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Energy requirements and environmental concerns have promoted a development in higher-efficiency coal fired power technologies. Advanced ultra-super critical power plant with an efficiency of higher than 50% is the target in the near future. The materials to be used due to the tougher environments become therefore critical issues. This paper provides a review on a newly developed advanced high strength heat resistant austenitic stainless steel, Sandvik Sanicro 25, for this purpose. The material shows good resistance to steam oxidation and flue gas corrosion, and has higher creep rupture strength than any other austenitic stainless steels available today, and has recently obtained two AMSE code cases. This makes it an interesting option in higher pressures/temperature applications. In this paper, the material development, structure stability, creep strength, steam oxidation and hot corrosion behaviors, fabricability and weldability of this alloy have been discussed. The conclusion is that the Sanicro 25 is a potential candidate for superheaters and reheaters in higher-efficiency coal fired boilers i.e. for applications seeing up to 700°C material temperature.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 881-891, October 22–25, 2013,
... covered the half of sample. Table 1: Test matrix Gas composition T [°C] 2%O2-29%H2O44%CO20.6%SO2-0.2HClN2 650 720 Used deposit CaCO3 - 15 CaSO4 wt% CaCO3 - 14 wt% CaSO4-1 KCl CaCO3 - 15 CaSO4 wt% CaCO3 - 14 wt% CaSO4-1 KCl Material S34710, S31035, N06617 S34710, S31035, N06617 S34710, S31035 S34710...
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Oxyfuel combustion is considered as one of the most promising technologies to facilitate CO 2 capture from flue gases. In oxyfuel combustion, the fuel is burned in a mixture of oxygen and recirculated flue gas. Flue gas recirculation increases the levels of fireside CO 2 , SO 2 , Cl and moisture, and thus promotes fouling and corrosion. In this paper the corrosion performance of two superheater austenitic stainless steels (UNS S34710 and S31035) and one Ni base alloy (UNS N06617) has been determined in laboratory tests under simulated oxyfuel conditions with and without a synthetic carbonate based deposits (CaCO 3 - 15 wt% CaSO 4 , CaCO 3 - 14wt% CaSO 4 - 1 KCl) at 650 and 720°C up to 1000 hours. No carburization of the metal substrate was observed after exposure to simulated oxyfuel gas atmospheres without deposit, although some carbon enrichment was detected near the oxide metal interface. At 720°C a very thin oxide formed on all alloy surfaces while the weight changes were negative. This negative weight change observed is due to chromium evaporation in the moist testing condition. At the presence of deposits, corrosion accelerated and considerable metal loss of austenitic alloys was observed at 720°C. In addition, clear carburization of austenitic steel UNS S34710 occurred.
Proceedings Papers
AM-EPRI2024, Advances in Materials, Manufacturing, and Repair for Power Plants: Proceedings from the Tenth International Conference, 495-506, October 15–18, 2024,
... in printing strategy e.g. stringer vs weaving beads, alternating printing direction or variation in shielding gas composition etc. which is the target of another study currently carried out. REFERENCES [1] R. Baker, Method of making decorative articles, US Patent 1,533,300 (1925) [2] A. Ujiie, Method...
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Additive manufacturing is a groundbreaking manufacturing method that enables nearly lossless processing of high-value materials and produces complex components with a level of flexibility that traditional methods cannot achieve. Wire arc additive manufacturing (WAAM), utilizing a conventional welding process such as gas metal arc welding, is one of the most efficient additive manufacturing technologies. The WAAM process is fully automated and guided by CAD/CAM systems on robotic or CNC welding platforms. This paper explores the fundamental concepts and metallurgical characteristics of WAAM. It focuses primarily on the mechanical properties of printed sample structures made from P91, X20, and alloys 625 and 718 wire feedstock. The study particularly addresses the anisotropy of mechanical properties through both short-term and long-term testing, comparing these results to materials processed using conventional methods.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 74-85, October 22–25, 2013,
... (equivalent to >90% reduction for a coalonly plant The effects of steam-side degradation and any enhancement due to oxy-combustion will also be included. The life model includes corrosion models that are derived from extensive laboratory testing and are a function of gas composition, deposition composition...
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The EU NextGenPower-project aims at demonstrating Ni-alloys and coatings for application in high-efficiency power plants. Fireside corrosion lab and plants trials show that A263 and A617 perform similar while A740H outperforms them. Lab tests showed promising results for NiCr, Diamalloy3006 and SHS9172 coatings. Probe trials in six plants are ongoing. A617, A740H and A263 performed equally in steamside oxidation lab test ≤750°C while A617 and A740H outperformed A263 at 800°C; high pressure tests are planned. Slow strain rate testing confirmed relaxation cracking of A263. A creep-fatigue interaction test program for A263 includes LCF tests. Negative creep of A263 is researched with gleeble tests. A263 Ø80 - 500mm trial rotors are forged with optimized composition. Studies for designing and optimizing the forging process were done. Segregation free Ø300 and 1,000mm rotors have been forged. A263 – A263 and A293 – COST F rotor welding show promising results (A263 in precipitation hardened condition). Cast step blocks of A282, A263 and A740H showed volumetric cracking after heat treatment. New ‘as cast’ blocks of optimized composition are without cracks. A 750°C steam cycle has been designed with integrated CO 2 capture at 45% efficiency (LHV). Superheater life at ≤750°C and co-firing is modeled.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 771-782, October 21–24, 2019,
... cooled relative to the gas stream [5,6]. Deposited species can include alkali metal sulphates and chlorides, as well as compounds that contain calcium, magnesium, vanadium, silicon and aluminium [7,8]. Depending on the local gas compositions and substrate temperatures, such deposits can react to cause...
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Key components within gas turbines, such as the blades, can be susceptible to a range of degradation mechanisms, including hot corrosion. Hot corrosion type mechanisms describe a sequence of events that include the growth and fluxing of protective oxide scales followed by the degradation of the underlying coating/alloy; this can significantly reduce component lifetimes. To better understand the progress of this type of damage mechanism, a model of hot corrosion progression with both time and corrosive deposit flux is presented for IN738LC and compared to experimental test data collected at 700 °C for four different deposit fluxes. One approach to the interpolation of model parameters between these four fluxes is illustrated. Of particular importance is that the model accounts for the statistical variation in metal loss though the use of Weibull statistics.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 268-287, August 31–September 3, 2010,
... in the combustion facility at various locations 284 corresponding to the lower furnace walls and superheaters. The gas compositions were determined in-situ with online instrumentations, including FTIR, GC and Horiba multi-gas analyzer. The in-furnace gas measurements revealed the coexistence of reducing...
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A comprehensive fireside corrosion study was undertaken to better understand the corrosion mechanisms operating on the superheaters and lower furnace walls of advanced coal- fired utility boilers. The study intended to evaluate the fireside conditions generated from burning eight U.S. coals individually in a pilot-scale combustion facility. These coals consisted of a wide range of compositions that are of interest to the utility industry. The combustion facility was capable of producing the realistic conditions of staged combustion existing in coal-fired utility boilers. During each of the combustion tests, gas and deposit samples were collected and analyzed via in-furnace probing at selected locations corresponding to the waterwalls and superheaters. Testing of five of the eight coal groups has been completed to date. Results of these online measurements helped reveal the dynamic nature of the combustion environments produced in coal-fired boilers. Coexistence of reducing and oxidizing species in the gas phase was evident in both combustion zones, indicating that thermodynamic equilibrium of the overall combustion gases was generally unattainable. However, the amount of sulfur released from coal to form sulfur-bearing gaseous species in both the reducing and oxidizing zones was in a linear relationship with the amount of the total sulfur in coal, independent of the original sulfur forms. Such a linear relationship was also observed for the measured HCl gas relative to the coal chlorine content. However, the release of sulfur from coal to the gas phase appeared to be slightly faster and more complete than that of chlorine in the combustion zone, while both sulfur and chlorine were completely released and reacted to form respective gaseous species in the oxidizing zone. The information of sulfur and chlorine release processes in coal combustion generated from this study is considered new to the industry and provides valuable insight to the understanding of fireside corrosion mechanisms.
Proceedings Papers
AM-EPRI2024, Advances in Materials, Manufacturing, and Repair for Power Plants: Proceedings from the Tenth International Conference, 573-581, October 15–18, 2024,
... toughness. Consequently, a comprehensive examination of the welded joints outlines manufacturing conditions, limitations, and the applications of SDSS and HDSS filler metals. chemical composition corrosion performance gas tungsten arc welding impact toughness microstructure optical microscopy...
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Super Duplex stainless steels (SDSS) are alloys based on the Fe-Cr-Ni-N system. The chemical composition is tailored to achieve a balanced microstructure of 50% ferrite and 50% austenite. Hyper Duplex Stainless Steels (HDSS) are also duplex materials distinguished by their remarkable yield strength (≥700 MPa) and corrosion resistance (PREN>48). They have been developed as an alternative to the well-established SDSS when superior mechanical and corrosion performance is required. This enhanced performance is attributed to alloying additions, primarily Cr, Mo, and N. In this study, a comparison is conducted between filler metals of SDSS and HDSS for the root welding of SDSS plates. The gas tungsten arc welding (GTAW) process was used to carry out root welding passes and Gas Metal Arc Welding (GMAW) for filling passes on SDSS substrates arranged in a V groove to simulate a repair scenario. The heat input was controlled in both processes, keeping it below 2.0 kJ/mm in the GTAW and 1.2 kJ/mm in the GMAW. GTAW with constant current was used and the parameters achieved producing full penetration welds with SDSS and HDSS. In this case, Nitrogen was used as backing gas to avoid oxidation of the root. Thus, a special GMAW-Pulsed version was applied to achieve good wettability and defect-free joints. ASTM G48 tests were performed to evaluate the corrosion resistance through Critical Pitting Testing (CPT) analysis on the root pass, microstructural analysis via optical microscopy, and impact toughness. Consequently, a comprehensive examination of the welded joints outlines manufacturing conditions, limitations, and the applications of SDSS and HDSS filler metals.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 1422-1431, October 22–25, 2013,
... containing alkali sulfate applied to the sample surface, so as to simulate fire-side coal ash deposition. Table 2 shows the conditions of the high temperature corrosion test regime. The target compositions of synthetic flue gas were (0.2 or 1.0)SO2+2.6O2+14CO2+10H2O+bal.N2 (vol to evaluate coal fuel...
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Six types of solution treated Ni-based alloy plates having a thickness of 25mm, namely Alloy 617, Alloy 263, Alloy 740, Alloy 141, HR6W (45Ni-23Cr-7W) and HR35 (50Ni-30Cr-4W-Ti) for advanced-USC boilers, were subjected to corrosion testing. In addition, three types of conventional ferritic and five types of conventional austenitic stainless tubes were also tested to compare their corrosion properties. Hot corrosion tests were conducted in order to assess the effects of temperature, material composition and coal ash composition on hot corrosion. The maximum average metal loss and the maximum corrosion rate were observed under 700°C test conditions. Cr content in the materials played an important role in the corrosion rate, with higher Cr content materials tending to show lower rates. However, Ni-based alloy materials showed slightly greater corrosion rates than those of stainless steels having equivalent Cr content in the over-700°C test condition. It was considered that rich Ni in the alloys easily reacted with sulfur, thus forming corrosion products having low melting points, such that corrosion was accelerated. The concentration of Fe 2 O 3 and NiO in the synthetic coal ash was also observed to affect the corrosion rate.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 303-311, August 31–September 3, 2010,
... the conditions of the high temperature corrosion test regime. The target compositions of synthetic flue gas were (0.02 or 0.20 or 1.0) SO2+2.6O2+14CO2+10H2O+bal.N2 (vol to 304 evaluate coal fuel with low, medium and high sulfur content respectively. The gas flowed through the test chamber at a rate of 200cc/min...
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Coal ash corrosion testing was conducted on six solution-treated nickel-based alloy plates (Alloy 617, Alloy 263, Alloy 740, Alloy 141, HR6W [45Ni-23Cr-7W], and HR35 [50Ni-30Cr-4W-Ti]) intended for advanced-USC boilers, along with conventional ferritic and austenitic stainless tubes for comparison. Tests used synthetic coal ash (Na 2 SO 4 , K 2 SO 4 , Fe 2 O 3 ) with varying SO 2 concentrations (0.02-1.00 vol%). Results showed maximum metal loss at 700°C, with higher SO 2 levels causing increased corrosion. Materials with higher chromium content demonstrated better corrosion resistance, suggesting chromium content is a crucial factor in material selection for these applications.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 830-835, October 21–24, 2019,
... and T. Goto, Compositional regions of single phases at 1800 ºC in Mo-rich Mo Si B ternary system , Materials Science and Engineering A, 552 (2012), pp. 179 188. [5] K. Yoshimi, T. Iizawa, S. Yamamoto, J. Nakamura, K. Maruyama, H. Katsui and T. Goto, Proc. Int. Gas Turbine Cong., (2015), pp. 319-327...
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MoSiBTiC alloy is a promising material for advanced aerospace applications and next generation high pressure turbine blades in jet engines and gas turbines. It mainly consists of Mo solid solution, TiC and Mo 5 SiB 2 phases and has creep strength much stronger than Ni-base superalloys and better than SiC/SiC ceramic matrix composites. Furthermore, the fracture toughness of the alloy is much better (>15 MPa(m) 1/2 ) than Mo-Si-B ternary alloys (<10 MPa(m) 1/2 ) even if the volume fraction of Mo solid solution is less than 50 %. The improvement of fracture toughness would be caused not only by the continuity of Mo solid solution in solidification microstructure but also by TiC phase affecting as a fracture-resistant phase. In order to understand the microstructure evolution during solidification and the effect of TiC phase on the fracture toughness of the MoSiBTiC alloy, Mo-Ti-C ternary model alloys are dealt with in this study. Then, (1) liquidus surface projection and (2) isothermal section and the elastic moduli of TiC phase in equilibrium with Mo solid solution were focused on. The obtained liquidus surface projection suggests that the ternary transition peritectic reaction (L+ Mo 2 C->Mo+TiC) takes place in Mo-rich region. At 1800 °C, TiC phase in equilibrium with Mo phase contains at least 20.2 at% Mo and the Mo/TiC/Mo 2 C three phase region should exist around Mo-15Ti-10C.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 213-223, October 11–14, 2016,
... and facilitate the design of Ni-base superalloys. compositional dependence gas turbine engines mechanical properties microstructure nickel-base superalloys niobium content phase precipitation phase stability physical properties Advances in Materials Technology for Fossil Power Plants Proceedings...
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Modern polycrystalline Ni-base superalloys for advanced gas turbine engines have been a key component that has contributed to technological advances in propulsion and power generation. As advanced turbine engine designs are beginning to necessitate the use of materials with temperature and strength capabilities beyond those exhibited by existing materials, new alloying concepts are required to replace conventional Ni-base superalloys with conventional γ-γ’ microstructures. The phase stability of various high Nb content Ni-base superalloys exhibiting γ-γ’-δ -η microstructures have been the subject of a number of recent investigations due to their promising physical and mechanical properties at elevated temperatures. Although high overall alloying levels of Nb, Ta and Ti are desirable for promoting high temperature strength in γ-γ’ Ni-base superalloys, excessive levels of these elements induce the formation of δ and η phases. The morphology, formation, and composition of precipitate phases in a number of experimental alloys spanning a broad range of compositions were explored to devise compositional relationships that can be used to predict the microstructural phase stability and facilitate the design of Ni-base superalloys.
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