Developing an austenitic stainless steel for improved performance in advanced fossil power facilities

Maziasz, P.J.

doi:10.1007/bf03220265

Cited by 54 publications

(51 citation statements)

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“…These potent carbide-forming elements and the addition of a dedicated thermomechanical treatment (TMT) results in an alloy with an austenitic matrix containing a dispersion of ultra-fine MC carbides [2,3,5]. This finely-precipitated MC phase, which readily pins dislocations and prevents recovery of the deformed dislocation substructure [3], is reported to be rich in Ti and Nb [2,3,5] in HT-UPS alloys that are very similar in composition to the HT-UPS alloy investigated in this work.…”

Section: Introductionmentioning

confidence: 99%

“…HT-UPS alloys offer improved strength and creep resistance over conventional stainless steels, particularly at temperatures in excess of 600 °C [2][3][4]. Developed in the 1980s through a study to develop alloys for elevated temperature fossil fuel applications, HT-UPS has already been subjected to extensive studies covering the basic mechanical properties [2][3][4][5] and related microstructural evolution [6] following exposure to standard creep testing, but relatively little research has been carried out to specifically elucidate the combined creep-fatigue behavior of any of the HT-UPS variants [7]. In service, components will be subjected to pressure-and temperature-related stresses that are prone to fluctuations along with being held constant for extended periods of time.…”

Section: Introductionmentioning

confidence: 99%

“…Currently, the heat-resistant components in fast reactors consist primarily of standard austenitic stainless steels that operate in the temperature regime of 600 to 650 °C [1]. One type of advanced austenitic material that might replace the more conventional stainless steels is a high-temperature ultrafine-precipitation-strengthened (HT-UPS) alloy [2]. HT-UPS alloys offer improved strength and creep resistance over conventional stainless steels, particularly at temperatures in excess of 600 °C [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…One type of advanced austenitic material that might replace the more conventional stainless steels is a high-temperature ultrafine-precipitation-strengthened (HT-UPS) alloy [2]. HT-UPS alloys offer improved strength and creep resistance over conventional stainless steels, particularly at temperatures in excess of 600 °C [2][3][4]. Developed in the 1980s through a study to develop alloys for elevated temperature fossil fuel applications, HT-UPS has already been subjected to extensive studies covering the basic mechanical properties [2][3][4][5] and related microstructural evolution [6] following exposure to standard creep testing, but relatively little research has been carried out to specifically elucidate the combined creep-fatigue behavior of any of the HT-UPS variants [7].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Hold Time on Creep-Fatigue Behavior of an Advanced Austenitic Alloy

Carroll¹,

Carroll²

2011

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An advanced austenitic alloy, HT-UPS (high-temperature ultrafineprecipitation-strengthened), has been identified as an ideal candidate material for the structural components of fast reactors and energy-conversion systems. HT-UPS alloys demonstrate improved creep resistance relative to 316 stainless steel (SS) through additions of Ti and Nb, which precipitate to form a widespread dispersion of stable nanoscale metallic carbide (MC) particles in the austenitic matrix. The low-cycle fatigue and creep-fatigue behaviors of an HT-UPS alloy have been investigated in air at 650 °C and 1.0% total strain, with an R-ratio of -1 and hold times as long as 9.0x10 3 sec at peak tensile strain. The cyclic deformation response of HT-UPS is directly compared to that of standard 316 SS. The measured values for total cycles to failure are similar, despite differences in peak stress profiles and in qualitative observations of the deformed microstructures. Crack propagation is primarily transgranular in fatigue and creep-fatigue of both alloys at the investigated conditions. Internal grain boundary damage in the form of fine cracks resulting from the tensile hold is present for hold times of 3.6x10 3 sec and longer, and substantially more internal cracks are quantifiable in 316 SS than in HT-UPS. The dislocation substructures observed in the deformed material differ significantly; an equiaxed cellular structure is observed in 316 SS, whereas in HT-UPS the microstructure takes the form of widespread and relatively homogenous tangles of dislocations pinned by the nanoscale MC precipitates. iv v ACKNOWLEDGEMENTSThe authors would like to acknowledge Joel Simpson and Randy Lloyd for the mechanical testing, Julian Benz for the optical metallography, and Tammy Trowbridge for the SEM work, and Todd Morris for the metallurgical sample preparation. The authors would also like to thank Jeremy Busby, Yukinori Yamamoto, Sam Sham and Lizhen Tan at Oak Ridge National Laboratory (ORNL) both for supplying the hot rolled HT-UPS material and for thoughtful guidance and discussions regarding this subject matter.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Hold Time on Creep-Fatigue Behavior of an Advanced Austenitic Alloy

Carroll¹,

Carroll²

2011

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“…13(c)). These "needle-shaped" precipitates were reported to be phosphides (MP) in the literature [Maziasz 1989, Lee et al 1984, 2000, Swinderman et al 1987, 1990. Grain boundaries are heavily decorated by precipitates after aging for 7595 h at 650°C.…”

Section: Relationship Between Microstructural Changes and Tensile Behmentioning

confidence: 97%

Report on thermal aging effects on tensile properties of advanced austenitic steels.

Li¹,

Natesan²,

Soppet³

et al. 2012

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This report provides an update on the evaluation of thermal-aging induced degradation of tensile properties of advanced HT-UPS austenitic stainless steels. The report is the second deliverable (level 3) in FY11 (M3A11AN04030103), under the Work Package A-11AN040301, "Advanced Alloy Testing" performed by Argonne National Laboratory, as part of Advanced Structural Materials Program for the Advanced Reactor Concepts. This work package supports the advanced structural materials development by providing tensile data on aged alloys and a mechanistic model, validated by experiments, with a predictive capability on long-term performance.The scope of work is to evaluate the effect of thermal aging on the tensile properties of advanced alloys such as ferritic-martensitic steels, mod.9Cr-1Mo (G91), G92, and advanced austenitic stainless steel, HT-UPS. The aging experiments have been conducted over a temperature of 550-750°C for various time periods to simulate the microstructural changes in the alloys. In addition, a mechanistic model based on thermodynamics and kinetics has been used to address the changes in microstructure of the alloys as a function of time and temperature, which is developed in the companion work package at ANL. The focus of this project is advanced alloy testing and understaning the effects of long-term thermal aging on the tensile properties.The first deliverable of FY11 reported the tensile testing results of thermally-aged G92 in the normalized and tempered condition (H1 G92), G92 in the cold-rolled condition (H2 G92), and reference alloy, G91 ferritic-martensitic steels. This report summarizes the tensile data of thermally aged HT-UPS austenitic stainless steel. Two heats of HT-UPS have been investigated, i.e., solution-annealed HT-UPS (SA HT-UPS) and hot-rolled HT-UPS (HR HT-UPS). Tensile data have been obtained for SA HT-UPS thermally-aged for up to 18031 h at 550°C and for up to 17595 h at 650°C, as well as for HR HT-UPS thermally aged for up to 6909 h at 550°C, 4293 h at 600°C, and 5407 h at 650°C.Major finding are: (1) the solution-annealed HT-UPS showed continued, moderate increase in strength and decrease in ductility with increasing aging time up to 18034 h at 550°C. Thermal aging at 650°C increased the yield stress and decreased the ultimate tensile strength and drastically reduced the ductility in the SA HT-UPS. For the HR HT-UPS, thermal aging at 550°C for up to 6909 h showed little influence on its tensile behavior. Thermal aging at 600°C for 4293 h increased the strength and decreased the ductility. The 650°C-thermally-aged HR HT-UPS specimens showed very different strengthening, strain hardening, and flow localization behavior. Thermal aging at 650°C increased the yield stress but decreased the ultimate tensile stress for the HR HT-UPS. (2) Dynamic strain aging (DSA) was observed in both the solution-annealed HT-UPS and the hot-rolled HT-UPS at temperatures between 550-650°C at a strain rate of 0.001 s -1 . Extensive precipitation in the matrix after thermal aging at 600 and ...

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Hot deformation behavior and processing map of a Fe‐25Ni‐16Cr‐3Al alumina‐forming austenitic steel

Sun

Zhou

et al. 2018

Materialwissenschaft Werkst

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The hot deformation behavior of a Fe‐25Ni‐16Cr‐3Al alumina‐forming austenitic steel was studied by hot compression using a Gleeble‐3500 thermal simulator. The compression tests were carried out in the temperatures range from 925 °C to 1175 °C and strain rates range from 0.01 s‐1 to 10 s‐1. It was concluded that the flow stress increased with decreasing deformation temperature and increasing strain rate. The constitutive equation was obtained and the activation energy was 420.98 kJ⋅mol‐1 according to the testing data. According to the achieved processing map, the optimal processing domain is determined in the temperatures range of 1050 °C – 1075 °C and strain rates range of 0.03 s‐1 ‐ 0.3 s‐1. The evolution of microstructure characterization is consistent with the rules predicted by the processing map. During compression at the same temperature, the higher the strain rate is, the higher the hardness will be. The ultimate tensile strength of the steel is 779 MPa with a total elongation of 27.1 % at room temperature.

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Developing an austenitic stainless steel for improved performance in advanced fossil power facilities

Cited by 54 publications

References 3 publications

Influence of Hold Time on Creep-Fatigue Behavior of an Advanced Austenitic Alloy

Influence of Hold Time on Creep-Fatigue Behavior of an Advanced Austenitic Alloy

Report on thermal aging effects on tensile properties of advanced austenitic steels.

Hot deformation behavior and processing map of a Fe‐25Ni‐16Cr‐3Al alumina‐forming austenitic steel

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