Evaluation of Alumina-Forming Austenitic Foil for Advanced Recuperators

2010 ◽  
Author(s):  
Bruce A. Pint ◽  
Michael P. Brady ◽  
Yukinori Yamamoto ◽  
Michael L. Santella ◽  
Philip J. Maziasz ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Oxidation Resistance ◽  
Creep Strength ◽  
Oxidation Behavior ◽  
Alumina Scale ◽  
Exhaust Gas ◽  
Commercial Batch ◽  
Oxidation Testing ◽  
Thick Foil

A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. By optimizing the Al and Cr contents, the alloy is fully austenitic for creep strength while allowing the formation of a chemically-stable external alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. As a first step in producing foil for primary surface recuperators, three commercially cast heats have been rolled to ∼100μm thick foil in the laboratory to evaluate performance in creep and oxidation testing. Results from initial creep testing are presented at 675° and 750°C showing excellent creep strength compared to other candidate foil materials. Laboratory exposures in humid air at 650°-800°C have shown acceptable oxidation resistance. Similar oxidation behavior was observed for sheet specimens of these alloys exposed in a modified 65kW microturbine for 2,871h. One composition that showed superior creep and oxidation resistance has been selected for preparation of a commercial batch of foil.

Evaluation of Alumina-Forming Austenitic Foil for Advanced Recuperators

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Bruce A. Pint ◽  
Michael P. Brady ◽  
Yukinori Yamamoto ◽  
Michael L. Santella ◽  
Philip J. Maziasz ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Oxidation Resistance ◽  
Creep Strength ◽  
Oxidation Behavior ◽  
Alumina Scale ◽  
Exhaust Gas ◽  
Commercial Batch ◽  
Oxidation Testing ◽  
Thick Foil

A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. By optimizing the Al and Cr contents, the alloy is fully austenitic for creep strength while allowing the formation of a chemically stable external alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. As a first step in producing foil for primary surface recuperators, three commercially cast heats have been rolled to ∼100 μm thick foil in the laboratory to evaluate performance in creep and oxidation testing. Results from initial creep testing are presented at 675°C and 750°C, showing excellent creep strength compared with other candidate foil materials. Laboratory exposures in humid air at 650–800°C have shown acceptable oxidation resistance. A similar oxidation behavior was observed for sheet specimens of these alloys exposed in a modified 65 kW microturbine for 2871 h. One composition that showed superior creep and oxidation resistance has been selected for the preparation of a commercial batch of foil.

Evaluation of Commercial Alumina-Forming Austenitic Foil for Advanced Recuperators

2011 ◽  
Author(s):  
Bruce A. Pint ◽  
Michael P. Brady ◽  
Yukinori Yamamoto ◽  
Kinga A. Unocic ◽  
Wendy J. Matthews
Keyword(s):  
Stainless Steel ◽  
Water Vapor ◽  
Austenitic Stainless Steel ◽  
Oxidation Resistance ◽  
Creep Strength ◽  
Alumina Scale ◽  
Exhaust Gas ◽  
Commercial Alumina ◽  
Thick Foil

A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. This fully austenitic alloy is optimized for creep strength while allowing the formation of a chemically-stable external alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. The first batch of commercially fabricated foil was produced with a composition selected from prior laboratory creep and oxidation results. The results for ∼80 and ∼105μm thick foil are compared to the prior laboratory-fabricated foils and other commercial candidates. Results from initial creep testing at 750°C show comparable creep strength to other commercial Fe-base foil candidates. Laboratory exposures in humid air at 650°–800°C have shown excellent oxidation resistance for this composition. Similar oxidation resistance was observed for sheet specimens of the first set of alloys exposed in a modified 65kW microturbine for up to 6,000h.

Stainless Steels With Improved Oxidation Resistance for Recuperators

2004 ◽  
Vol 128 (2) ◽  
pp. 370-376 ◽  
Author(s):  
Bruce A. Pint
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Oxidation Resistance ◽  
Stainless Steels ◽  
Lower Cost ◽  
Exhaust Gas ◽  
New Materials ◽  
Excellent Corrosion Resistance ◽  
Gas Environment

New materials are being evaluated to replace type 347 stainless steel in microturbine recuperators operating at higher temperatures in order to increase the efficiency of the microturbine. Commercial alloys 120 and 625 are being tested along with potentially lower cost substitutes, such as Fe-20Cr-25Ni and Fe-20Cr-20Ni. Long-term testing of these materials at 650–700 °C shows excellent corrosion resistance to a simulated exhaust gas environment. Testing at 800 °C has been used to further differentiate the performance of the various materials. The depletion of Cr from foils of these materials is being used to evaluate the rate of attack. Although those alloys with the highest Ni and Cr contents have longer lives in this environment, lower alloyed steels may have sufficient protection at a lower cost.

Stainless Steels With Improved Oxidation Resistance for Recuperators

2004 ◽  
Author(s):  
Bruce A. Pint ◽  
Karren L. More
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Oxidation Resistance ◽  
Stainless Steels ◽  
Lower Cost ◽  
Exhaust Gas ◽  
New Materials ◽  
Excellent Corrosion Resistance ◽  
Gas Environment

New materials are being evaluated to replace type 347 stainless steel in microturbine recuperators operating at higher temperatures in order to increase the efficiency of the microturbine. Commercial alloys 120 and 625 are being tested along with potentially lower cost substitutes such as Fe-20Cr-25Ni and Fe-20Cr-20Ni. Long-term testing of these materials at 650°–700°C shows excellent corrosion resistance to a simulated exhaust gas environment. Testing at 800°C has been used to further differentiate the performance of the various materials. The depletion of Cr from foils of these materials is being used to evaluate the rate of attack. While those alloys with the highest Ni and Cr contents have longer lives in this environment, lower alloyed steels may have sufficient protection at a lower cost.

scholarly journals Oxidation behavior of 316L austenitic stainless steel in high temperature air with long-term exposure

2020 ◽  
Vol 7 (6) ◽  
pp. 066517
Author(s):  
Xi Huang ◽  
Kai Xiao ◽  
Xiaodong Fang ◽  
Zicheng Xiong ◽  
Lihua Wei ◽  
...  
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Austenitic Stainless Steel ◽  
Oxidation Behavior ◽  
316L Austenitic Stainless Steel

Development of Alumina-Forming Austenitic Alloys for Advanced Recuperators

2009 ◽  
Author(s):  
Bruce A. Pint ◽  
Michael P. Brady ◽  
Yukinori Yamamoto ◽  
Michael L. Santella ◽  
Jane Y. Howe ◽  
...  
Keyword(s):  
Water Vapor ◽  
Gas Turbines ◽  
Laboratory Data ◽  
Austenitic Stainless Steels ◽  
Alumina Scale ◽  
Exhaust Gas ◽  
Alloy Development ◽  
Creep Properties ◽  
New Class

A new class of corrosion- and creep-resistant austenitic stainless steels has been developed for advanced recuperator applications. The Al and Cr contents have been optimized to maintain a fully austenitic composition for creep strength while allowing the formation of a highly-protective external alumina scale at temperatures up to 900°C in the presence of water vapor. Strengthening was achieved via the formation of stable nano-scale MC type carbides and creep properties were comparable to commercially available advanced austenitic stainless steel alloys. These properties are particularly well-suited for thin-walled recuperators for both small and large gas turbines and fuel cells. By forming an alumina scale, long-term problems with Cr evaporation in the presence of water vapor in the exhaust gas are eliminated. Laboratory data are presented from humid air and microturbine exhaust gas to illustrate the oxidation resistance of this class of alloys at 650°–900°C and compared to results for some current commercial alloys. Alloy development is continuing in order to determine the effect of composition on performance over this temperature range.

scholarly journals Effect of Cr and Al alloying on the oxidation resistance of a Ti5Si3-incorporated MoSiBTiC alloy

2021 ◽  
Vol 40 (1) ◽  
pp. 204-213
Author(s):  
Xi Nan ◽  
Tomotaka Hatakeyama ◽  
Shuntaro Ida ◽  
Nobuaki Sekido ◽  
Kyosuke Yoshimi
Keyword(s):  
Solid Solution ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Oxide Scales ◽  
Accelerated Oxidation ◽  
Oxidation Test ◽  
Poor Oxidation Resistance

Abstract The effects of adding Cr and Al on the oxidation behavior of a Ti5Si3-incorporated MoSiBTiC alloy (46Mo–28Ti–14Si–6C–6B, at%) were investigated at 800 and 1,100°C. The addition of Cr and Al largely improved the oxidation resistance of the MoSiBTiC alloy at 800°C due to the formation of Cr2(MoO4)3 and Al2(MoO4)3 in the oxide scales. These protective molybdates mainly formed on the molybdenum solid solution (Moss) and Mo3Si phases that show poor oxidation resistance in the Cr- and Al-free alloy and consequently increased the oxidation resistance of the alloys. However, accelerated oxidation occurred on the 10Al alloy after the long-term oxidation test, suggesting that the formed oxide scale has limited protection ability. At 1,100°C, the addition of Cr and Al also enhanced the oxidation resistance to some extent by forming Cr2O3 and Al2O3 in the oxide scales.

Long-Term Oxidation Behavior of Selected High Temperature Alloys

2007 ◽  
Author(s):  
S. Krishna Srivastava ◽  
Michael J. Newburn ◽  
John P. Cotner ◽  
Mark A. Richeson
Keyword(s):  
High Temperature ◽  
Oxidation Behavior ◽  
Scanning Electron Micrographs ◽  
Corrosion Attack ◽  
Short Term ◽  
Haynes 230 ◽  
High Temperature Alloys ◽  
Oxidation Testing ◽  
Scanning Electron

Long-term oxidation behavior of alloys cannot be estimated reliably by extrapolation of short-term results; therefore long-term testing is imperative. Such data often are not available. Oxidation testing for a period of 360 days has been conducted for several high temperature alloys extensively used in the gas turbine industry. The alloys tested comprised of HASTELLOY® X alloy, HAYNES® 230®, HR-120®, and 214™ alloys, the first three being chromia forming and the last one being an alumina forming alloy. The specimens were exposed to flowing air at 1800°F(982°C), 2000°F(1093°C), 2100°F(1149°C) and 2200°F(1204°C). The tests were interrupted and the specimens were weighed every 30 days. At the completion of each test, the samples were examined metallographically to determine the internal attack. The magnitude of oxidation attack was studied in terms of the weight change and total metal affected. The paper will report the results of the long-term oxidation testing and the analysis of the corrosion attack with the optical and scanning electron micrographs. HASTELLOY, HAYNES, 230 and HR-120 are registered trademarks and 214 is a trademark of Haynes International, Inc.

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