Screening and Evaluation of Materials for Advanced Microturbine

Screening and Evaluation of Materials for Advanced Microturbine Recuperators Edgar Lara-Curzio, R. M. Trejo, K. L. More, P. A. Maziasz, B. A. Pint Metals & Ceramics Division Oak Ridge National Laboratory Oak Ridge, TN 37831 -6069 ASME Turbo Expo Vienna, Austria June 16, 2004 OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 1 of 45

Acknowledgments Research sponsored by the U. S. Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Power Technologies, Microturbine Materials Program, under contract DE-AC 05 -00 OR 22725 with UT-Battelle, LLC OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 2 of 45

Outline • Background • Microturbine Recuperator Testing Facility • Test Procedure • Results • 347 Stainless Steel • HR 230® • HR 120® • Summary, Current and Future Work OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 3 of 45

Outline • Background OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 4 of 45

Background $500/k. W 40% Efficiency 40, 000 -hr life U. S. DOE Advanced Microturbines Program 2000 2002 2004 2006 2008 OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 5 of 45 2010

Background (cont. ) $500/k. W 40% Efficiency advanced materials 40, 000 -hr life higher TET higher TIT 2000 U. S. DOE Advanced Microturbines Program 2002 2004 2006 2008 OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 6 of 45 2010

Background (cont. ) Main parameters to consider for the selection of materials for microturbine recuperators • Temperature • Environment (combustion gases can lead to corrosion) • Mechanical Stress (pressure differential can induce creep deformation) OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 7 of 45

Outline • Background • Microturbine Test Facility • Testing Procedure OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 8 of 45

Microturbine Test Facility As part of the Advanced Materials for Recuperators Program, ORNL established a microturbine test facility to screen and evaluate candidate materials for advanced microturbine recuperators shelter housing instrumentation gas compressor Capstone 60 k. W microturbine OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 9 of 45

ORNL’s Microturbine Test Facility (cont. ) thermocouples pressure transducer sample holder water lines water-cooled block • Modified Capstone C 60 microturbine • Higher TET (850°C) • Placement of test specimens at the entrance of recuperator. air line OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 10 of 45

Microturbine Test Facility (cont. ) OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 11 of 45

ORNL’s Microturbine Test Facility (cont. ) • Four (4) laser-welded foils in each sample holder welded foils • foil temperatures are monitored using type-K thermocouples • sample holders are pressurized with air to simulate the pressure differential experienced by recuperator cells sample holder thermocouples OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 12 of 45

Temperature distribution along sample holder TET=800°C OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 13 of 45

Effect of microturbine exposure on tensile properties Foils are removed from the sample holder and miniature test specimens, obtained by electric discharge machining, are evaluated in tension. OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 14 of 45

Temperature History for 500 -hr test OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 15 of 45

Outline • Background • Microturbine Test Facility • Testing Procedure • Results • 347 Stainless Steel OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 16 of 45

347 -stainless steel after 500 -hr exposure (TET=800°C) D 632°C 0. 089 mm C B A 697°C 736°C 758°C OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY 0. 089 mm 60 psi internal pressure -> 50 MPa hoop stress Lara-Curzio et al. IGTI-2004. Page 17 of 45

347 -stainless steel after 500 -hr exposure ballooning due to creep deformation Significant corrosion and spalling of oxidation products on foil exposed to highest temperature (758°C) OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 18 of 45

347 -stainless steel after 500 -hr exposure hot end 758°C cool end 630°C ballooning due to creep deformation D C B A cross-sectional analysis exhaust side Position D 500 h @ ~632°C very little corrosion Position C 500 h @ ~697°C thin scale Position B 500 h @ ~736°C ~3 µm scale air side OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY “wart” Lara-Curzio et al. IGTI-2004. Page 19 of 45 Position A 500 h @ ~758°C ~20 µm scale

347 -stainless steel after 500 -hr exposure exhaust side air side Foil exposed at 758°C Foil A O • Multilayered oxide scale: • Ni-Cr-O • Fe-O Cr Nb • Depletion of Cr at GBs • Carbide formation Fe Ni OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 20 of 45

Tensile strength of as-processed 347 -stainless steel OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 21 of 45

Tensile strength of 347 -stainless steel OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 22 of 45

Tensile strength of 347 -stainless steel OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 23 of 45

Tensile strength of 347 -stainless steel OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 24 of 45

Tensile strength of 347 -stainless steel OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 25 of 45

Tensile strength of 347 -stainless steel • Dimples characteristic of plastic deformation. • Limited ductility • 758°C • 500 hrs • 50 MPa (hoop stress due to 60 psi of internal pressure) OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 26 of 45

Tensile strength 347 -stainless steel • 500 -hr test • 60 psi internal pressure OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 27 of 45

Outline • Background • Microturbine Test Facility • Testing Procedure • Results • 347 Stainless Steel • HR 230® OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 28 of 45

As-processed HR 230® tungsten-rich particles 89 µm 102 µm OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 29 of 45

HR 230® after 500 -hr exposure (TET=800°C) D 679°C C B A 700°C 730°C 752°C OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY 0. 089 mm 0. 102 mm 60 psi internal pressure Lara-Curzio et al. IGTI-2004. Page 30 of 45

HR 230® after 500 -hr exposure (TET=800°C) hot end 752°C cool end 679°C D C B A cross-sectional analysis exhaust side Position D 500 h @ ~679°C Position C 500 h @ ~697°C Position B 500 h @ ~730°C air side OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 31 of 45 Position A 500 h @ ~752°C

HR 230® after 500 -hr exposure (TET=800°C) Foil exposed at 752°C • Limited corrosion products found on surface • Significant cracking along grain boundaries C Cr Mo O W Ni • Grain boundaries near surface are poor in Cr but rich in W and C. OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 32 of 45

Tensile strength of HR 230® after 500 -hr exposure OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 33 of 45

Outline • Background • Microturbine Test Facility • Testing Procedure • Results • 347 Stainless Steel • HR 230® • HR 120® OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 34 of 45

HR 120® after 500 -hr exposure (TET=800°C) hot end 745°C cool end 632°C D C B A cross-sectional analysis exhaust side Position D 500 h @ ~632°C Position C 500 h @ ~700°C Position B 500 h @ ~730°C air side OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 35 of 45 Position A 500 h @ ~745°C

HR 120® after 500 -hr exposure (TET=800°C) Foil exposed at 745°C • Limited corrosion (oxides of Cr, Si and Fe) • Grain boundaries near surface are poor in Cr but rich in Ni 10 µm Fe Ni Si OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 36 of 45 Cr

Tensile strength of HR 120® after 500 -hr exposure OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 37 of 45

Tensile strength of metallic alloys after 500 -hr exposure OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 38 of 45

Outline • Background • Microturbine Test Facility • Testing Procedure • Results • 347 Stainless Steel • HR 230® • HR 120® • Summary, Current and Future Work OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 39 of 45

Summary, Current and Future Work • A test facility was designed to screen and evaluate candidate materials for advanced microturbine recuperators. • TET up to 850°C • Mechanical stressing • Foils of 347 stainless steel, HR 230® and HR 120® alloys have been evaluated • Foils have been welded to sample holders by laser and e-beam. OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 40 of 45

Summary, Current and Future Work (cont. ) • 347 stainless steel exhibited significant decrease in tensile strength and ductility, and severe corrosion after 500 -hr exposure at 758°C. • Evidence of creep deformation at temperatures above 700°C at 50 MPa. • Corrosion products at highest temperature a mixture of oxides of chromium, nickel and iron. • Depletion of chromium from grain boundaries near interface between base metal and oxide layers. • Carbide precipitation OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 41 of 45

Summary, Current and Future Work (cont. ) • HR 230® retains 70% of its tensile strength after 500 -hr exposure at 752°C. • Limited corrosion products found on surface but significant cracking along grain boundaries • Grain boundaries near surface are poor in chromium but rich in tungsten and carbon. OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 42 of 45

Summary, Current and Future Work (cont. ) • HR 120® exhibited good retention of mechanical properties (e. g. - 85% of its tensile strength) after 500 -hr exposure at 745°C. • Limited corrosion products in the form of oxide of chromium, silicon and iron. • Depletion of chromium from grain boundaries close to surface exposed to exhaust gases. OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 43 of 45

Summary, Current and Future Work (cont. ) • Tests in progress to evaluate HR 120®, HR 214®, HR 230®, ORNL-modified stainless steels, Fe. Cr. Al. Y alloys and alloy 625. • Effect of intermittent operation on durability of candidate materials OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 44 of 45

OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Lara-Curzio et al. IGTI-2004. Page 45 of 45