C O N F I D E N T. Prepared by. Name MOHD NASIR TAMIN. Universiti Teknologi Malaysia. Institution. : 16 June Date Submitted.

Transcription

1 C O N Performance Characterization of Advanced Alloys for High-temperature Recuperators Applications in Improved Efficiency Microturbines (3-1-6-SF45) F I D E N T Prepared by Name MOHD NASIR TAMIN I Institution Universiti Teknologi Malaysia A Date Submitted Date Printed 16 June 26 1 December 27 Produced by Ministry of Science, Technology and Innovation L

2 PROJECT IDENTIFICATION A. Project number SF45 B. Project title Performance Characterization of Advanced Alloys for High-temperature Recuperators Applications in Improved Efficiency Microturbines C. Project leader Name NRIC MOHD NASIR TAMIN D. Institution Name Address Tel. No. Fax. No. Universiti Teknologi Malaysia Pengarah Pusat Pengurusan Penyelidikan UTM E. Key words Microturbine High-temperature alloys Creep Oxidation resistance Recuperators in Improved Page 1 of 18

3 OBJECTIVES OF THE PROJECT A. Specific objective To establish properties and behavior of candidate materials for metallic recuperators that could safely operate at temperatures up to 9 C (a) to determine creep deformation of the alloys in the temperature range of 6-75 C. (b) to determine oxidation resistance of the alloys in the temperature range of C in air and simulated "service" environment. (c) to establish relations among design stress, operating temperatures and environment (with high watervapor pressure) (d) to identify the effects of manufacturing parameters (such as rolling direction, welding and metal foil thickness) on durability and reliability of recuperators. B. Type of research Applied research C. Research Cluster and SEO Categories being addressed by the Project Research Cluster SEO Category SEO Group SEO Area INDUSTRY - Advanced Material S25 - Energy Supply S251 - Energy Transformation S Gas electricity D. Fields of research Primary Field of Research - FOR Category - FOR Group - FOR Area F112 - Material Sciences F Advanced Materials F Metals and metal alloy materials Secondary Field of Research - FOR Category - FOR Group - FOR Area (if applicable) F112 - Material Sciences F Advanced Materials F Metals and metal alloy materials in Improved Page 2 of 18

4 RESEARCH BACKGROUND B. Research background of the project Project status New Project summary Literature review summary The development of clean and efficient microturbine system (1 kwe) utilizing natural gas is being proposed. The fuel-to-electricity conversion efficiency of at least 4 percent is achieveable. The use of natural gas ensures environmental superiority with NOx emission of less than 7 ppm. The target durability of the system demands 11, hours of operations between major overhauls and a service life of at least 45, hours. Such advanced microturbine will need to operate at higher temperatures and demand improved recuperator materials. In most design, microturbine recuperators are responsible for a significant fraction of the overall efficiency. Current microturbines utilize primary surface recuperators made of Type 347 stainless steel that operate at gas inlet temperatures of <65 oc to attain ~3% efficiency [Omatete, 1999]. For low-compression ratios (eg. 5), the only way to achieve efficiency targets to >4% involves the increase in turbine inlet temperatures (123 oc), and consequently recuperator inlet temperatures (843 oc). Material selection for recuperators is therefore based on the recuperator hot-gas inlet temperature. At elevated temperatures, these steels are succeptible to severe moisture-induced oxidation attack and mechanical/ creep deformation leading to structural deterioration and leaks, thus reducing the effectiveness and life of the recuperator. The research indicates the requirement to extend the temperature limit of recuperator materials (from 65 up to 9 oc) The first step in developing recuperators with upgraded performance is to characterize the current technology. Combination of oxidation and corrosion behavior and tensile and creep strength determine the upper temperature and useful lifetime limits. In this respect, creep tests on commercial 347 steel recuperator stock has been conducted [2]. Aging effects on the steel up to 3, hours above 7 oc has been established in terms of detrimental sigma phase formation [Minami et al., 1985]. Several stainless alloy including modified 83, alloy 23 and alloy 12 showed better creep strength at 75 oc than 347 stainless steel. In addition, Nibased superalloys such as alloy 625 and alloy 214 displayed superior creep resistance at this temperature and may be useful at 8 oc or above. Based on this studies, alloy 12 and modified alloy 83 are promising candidates for upgraded recuperator foils. An alternate means of improving creep resistance of commercial 347 stainless steel foil is through engineered microstructures. While properties and behavior of 347 steel is generally known for processing and fabrication into other high-temperature component such as heat-exchanger piping and gas turbine components, information on these alloys fabricated into thin foils (~1 µm thick) for use in primary surface recuperators is limited or nonexistent. Foils with fine grain sizes tend to have less creep resistance relative to coarse-grained products of the same composition. In corrosion studies of stainless steel foils (1 / \mm thickness) with <2 wt.% Cr, results showed that a short time rapid attack on 347 steel occurred in the presence of 1% water at 8 oc [Maziasz et al., 1999]. A thicker Fe-rich oxide (FeOx, (Fe,Cr)Ox) forms instead of a more protective Cr2O3. Stainless steel Alloy 321 displayed superior oxidation resistance with Cr2O3 layer formation in dry air at 8 oc for up to 5, hours. Ni-based superalloy such as Inconel 625(Ni-21Cr) has sufficient oxidation and creep resistance for use up to 7 oc. However, the cost is times that of steel [Maziasz et al., 24]. In addition, both Ni- and Fe-based alloys with >2 wt. % Cr demonstrated superior corrosion protection in recuperator environment. Investigation is therefore aimed at identifying the least expensive alloy with good corrosion protection as a cost-effective new alternatives to 347 stainless steels. Related research in Improved Page 3 of 18

5 1. The United States Department of Energy and microturbine manufacturers have been working together since 1999 to develop advanced microturbines. In the materials development program, actual materials test environment is obtained through an expensive (aboout RM2k) 6 kwe Capstone microturbine which is modified to accept sample holder bosses [Lara-Curzio et al., 22]. Results of the studies have identified the limit use of high-temperature alloys in typical recuperator operating environment [Stinton and Karnitz, 1999; Stinton and Raschke, 24]. 2. Solar Turbines, Allegheny-Lundlum and Oak Ridge National Lab, USA have established lab-scale processing of Type 347 stainless steel that produced improvements in creep resistance at temperatures of 65-7 oc for recuperator applications. For lab-air testing temperatures of oc, foils made of Fe- and Nibased alloys are evaluated. The aim is to identify the strengthening mechanisms in such foils and provide information necessary to help select down and optimize the processing of the best alloy. [Maziasz and Swindeman, 1999] 3. Investigation of composition optimization of recuperator alloys for corrosion resistance was performed by Pint (24). The effects of temperature, alloy grain size, phase composition and minor alloy additions on corrosion behavior of the foils were addressed. Several commercial alloys foils such as NF79, HR12 and 125 were oxidized for 1, hours in humid air at 65 and 7 oc. All foils showed selective grain boundary depletion of Cr near the surface which leads to Fe-rich nodule formation in NF79 and HR12 after exposure at 65 oc. in Improved Page 4 of 18

6 PROJECT SCHEDULE Activities Purchasing of research materials J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Design and fabrication of foil sample holder Design and fabrication of oxidation test rig Literature review Sample preparation (As-received, hotrolled, cold-worked and welded foils) Metallurgical characterization (Microstructures, elemental analysis) Mechanical tests Tension tests of bulk specimen --Reporting/ progres review/ coordination with microturbine team Mechanical tests Creep-rupture tests of foil samples Fractographic analysis Fractured samples from tension and creep-rupture Commissioning process of oxidation test rig Oxidation studies (5, hrs) --Technology transfer activities Paper presentation National/regional conference in Improved Page 5 of 18

7 --Participating in integration workshop (microturbine team) --Reporting/ progres review/ coordination with microturbine team Fractographic analysis Aged samples from oxidation tests --Reporting/ progres review/ coordination with microturbine team --Technology transfer activities Paper presentation National/regional conference Materials selection and ranking --Technology transfer activities Paper presentation - International conference --Participating in integration workshop (microturbine team) --Reporting/ progres review/ coordination with microturbine team Milestone Completion of fabrication of sample holder for foil oxidation test J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Completion of oxidation test rig including commissioning process Completion of metallurgical characterization of as-received, foil materials, and aged samples Completion of oxidation studies (5, hours) Completion of fractographic analysis (a) tension, creep-rupture and oxidation test specimen in Improved Page 6 of 18

8 Project Completion in Improved Page 7 of 18

9 SUMMARY OF RELEVANT PAST RESEARCH PROJECT A. Project title Fatigue Crack Growth Mechanisms in Titanium Metal Matrix Composites B. Research Team Programme head (if applicable) Dr. W. Jones Project leader Name Institution Professor Hamouda Ghonem University of Rhode Island (URI), USA C. Description of the project In this project, continuous SiC-fiber-reinforced Ti-metal matrix composite was evaluated as a candidate material for hot turbine disk application in military engines for United States Air Force. Sample composites were fabricated by Timet Materials Division in the form of 8-ply alternating o fiber mats and Ti-6242 foils and consolidated at temperature of 871 oc via vacuum hot-pressing technique. Series of fatigue crack growth tests were performed at room and elevated temperatures of 65 oc. Fatigue crack growth bridging mechanisms were identified through fractographic analysis. Creep and fatigue tests were also done on Ti alloy foils and SiC fibers, respectively. A total of 3 international journal papers, 6 international conference papers and 2 interim reports were published. D. Description how it is relevant to the proposed project Similar method of conducting tests on foil materials at elevated temperature of 65 oc will be employed. Skills and knowledge in microstructural characterization of advanced alloys and in failure mechanisms identification is equally matched. Experience in design and fabrication of test rigs (fiber push-out test and creep machine with dwell-time loading) will facilitate the design of water-vapor corrosion test rig and sample holder for the foils, as proposed in this project E. Other collaborator that were involved in the project F. Source of Funding Funding No. AFOSR-2-F Office of Scientific Research, Bolling Air Force Base, Ohio, USA in Improved Page 8 of 18

10 RESEARCH APPROACH A. Research methodology Candidate recuperator materials For use up to 7 oc Stainless steel 347 (modified processing and alloying), at 75-8 oc Ni-based alloy (12), modified 83 alloy, Ni-21Cr alloy, and above 8 oc Ni-Cr-Al alloys (214, 23) Task A. Specimen preparation -For Task B and C all foil samples are hot-rolled with post-processing heat-treatement -For Task D the thin foils are cold-worked by stamping, rolled, and welded to produce a closed cylindrical geometry with a specially designed sample holder. Task B. Metallurgical and microstructural characterization -As-received bulk materials and foil samples (for base-line data) -Aged foil samples (above 7 oc) by oxidation test -Failed foil samples by creep-rupture tests Task C. Mechanical characterization (air environment, room and elevated temperature levels) -Tension tests for mechanical properties of bulk materials (for base-line data) -Tension tests of foil samples -Creep-rupture tests of foil samples at different stress and temperature levels Task D. Oxidation studies at simulated service environment (with steam at 1 atm and elevated temperature levels); specimen is stressed by internal pressurization of the sample with the holder. -Hot corrosion tests of foil samples Task E. Fractographic analysis -Conducted on all failed/ fractured samples -Identify corrosion mechanisms Task F. Selection of candidate materials for specified recuperator operating environment -Determine stress-temperature-environment relationship for each material -Rank the materials with respect to performance superiority in a given operating temperature range and cost. Specialised Equipment Universal dynamic material testing machine Creep testing machine High-temperature chamber equipped for water vapor corrosion testing at 75-1 oc to simulate recuperator service environment. Facility Corrosion measurement facilities Metallurgical investigation and microstructural characterization facilities (XRD,GDS) Optical microscope and scanning electron microscope (SEM, FESEM). Infrastructure Hot-rolling and post-processing heat treatment of foil samples. Welding of foil samples made of candidate materials (stainless steel, specialty stainless alloys and superalloys) Description Existing Existing New Description Existing Existing Existing Description Existing Existing in Improved Page 9 of 18

11 B. Project activities Activities From Date To Date Literature review 1/12/26 1/6/28 Purchasing of research materials 1/12/26 1/12/26 Design and fabrication of oxidation test rig 1/12/26 1/3/27 Design and fabrication of foil sample holder 1/12/26 1/2/27 Metallurgical characterization (Microstructures, elemental analysis) 1/1/27 1/8/27 Sample preparation (As-received, hot-rolled, cold-worked and welded foils) 1/1/27 1/6/27 Mechanical tests Tension tests of bulk specimen 1/2/27 1/4/27 Mechanical tests Creep-rupture tests of foil samples 1/3/27 1/11/27 Fractographic analysis Fractured samples from tension and creep-rupture 1/3/27 1/9/28 Commissioning process of oxidation test rig 1/4/27 1/5/27 Oxidation studies (5, hrs) 1/6/27 1/3/28 --Reporting/ progres review/ coordination with microturbine team 1/9/27 1/9/27 Fractographic analysis Aged samples from oxidation tests 1/1/28 1/5/28 Materials selection and ranking 1/4/28 1/8/28 --Technology transfer activities Paper presentation National/regional conference 1/4/28 1/4/28 --Technology transfer activities Paper presentation - International conference 1/8/28 1/8/28 --Participating in integration workshop (microturbine team) 1/9/28 1/9/28 C. Key milestones Milestones Date Completion of metallurgical characterization of as-received, foil materials, and aged samples 1/8/27 Completion of fabrication of sample holder for foil oxidation test 1/3/27 Completion of oxidation test rig including commissioning process 1/6/27 Completion of oxidation studies (5, hours) 1/3/28 Completion of fractographic analysis (a) tension, creep-rupture and oxidation test specimen 1/6/28 Project Completion 1/9/28 D. Risks of the project Factor Technical risk Timing risk 1. Assembly and delivery of high-temperature corrosion test rig by appointed fabricator. 2. Delivery of hot-rolled foils, cold-work and welded foil samples by appointed fabricator. Low - Adequate experience of project team members on the technical aspect of the project. Medium - Reliability of the newly-designed high-temperature oxidation test rig will be untested. in Improved Page 1 of 18

12 Budget risk Low - Some out-sourcing of technical expertise is expected for cold-working and welding of foil samples and fabrication of test rig. E. Time schedule Starting date Completion date Duration 1/12/26 3/11/28 23 in Improved Page 11 of 18

13 BENEFITS OF THE PROJECT A. Outputs Expected from the project Research Quantity Details\Remark others 1 Database on properties and behavior of alloys (foils) for high-temperature humid applications New/improved material 2 Modified austenitic steels and superalloys for advanced recuperators Human capital and expert development Masters degrees Bachelor Research staff with new specialization Quantity Specialisation Area (specific area) 2 Applied mechanics and materials engineering 5 Applied mechanics and materials engineering 1 High-temperature alloy characterization B. Economic contributions of the project Cost savings Revenue from consultancies C. Infrastuctural contributions of the project New equipment New/ improved facility in Improved Page 12 of 18

14 RESEARCH COLLABORATION A. Institutions involved in the project Organisations Involved NUCLEAR - Malaysian Nuclear Agency Other Role Metallurgical study and creep testing B. Industries involved in the project Industry Role C. Project Team Project Leader Organisation Man-Month MOHD NASIR TAMIN Universiti Teknologi Malaysia 1.75 Researchers Organisation Man-Month Nazri bin Kamsah Universiti Teknologi Malaysia 3.46 Support Staff Type Number Man-Month Technical support staff Contract Staff Type Number Man-Month Engineering contract staff in Improved Page 13 of 18

15 DIRECT EXPENSES ESTIMATION WORKSHEET Expense Categories and Items Year 1 Year 2 Year 3 Year 4 Total Travel & contract personnel (V 11) CONTRACT STAFFS 3,9 42,75 13,5 6,15 Travel & transportation (V 21) International conference 1, 1, National/ regional conferences 6, 6, 12, Coordinating workshops 2, 2, 4, International conference 1, 1, Rental (V 24) None Research materials & supplies (V 26) Austenitic stainless steels 8, 8, Stainless alloy foils 1, 1, Chemicals 5, 5, Alloy for sample holder 5, 5, Consumables 5 2, 1,5 4, Minor modifications & repairs (V 28) Maintenance and operating cost of mechanical testing machines Special services (V 29) Use of equipment for chemical and materials analysis 5, 5, 1, 5, 2, 7, Fabrication/ modification of oxidation test rig 1, 1, Special equiment, accessories (V 35) Oxidation test rig with standard features 3, 3, Extensometer for creep-rupture test machine Total direct expenses 15, 15, 77,4 72,75 5, 2,15 in Improved Page 14 of 18

16 SPECIAL EQUIPMENT AND ACCESSORIES Item Justification Similar Equipment available Justification to purchase Estimation Cost Extensometer for creep-rupture test machine Extensometer for creep testing of foil/ thin sheet materials N For measurement of strains of the foil samples during creep-rupture tests. (Available extensometer is suited for cylindrical specimen) 15, Oxidation test rig with standard features Oxidation test rig for corrosion test up to 1 oc and flowing steam at 1 psig. The pressure vessel will be modified to accept holder for foil samples which is to be designed and fabricated. N To provide simulated service environment at the upstream/ inlet location of the microturbine recuperator 3, in Improved Page 15 of 18

17 PROJECT COST A. Salaried Personnel costs Staff Category Salaried personnel (V111) Year 1 (RM) Year 2 (RM) Year 3 (RM) Year 4 (RM) Total (RM) 5,31 31,56 12,98 49,85 Total salaried 5,31 31,56 12,98 49,85 B. Direct Project Expenses Expense Category Temporary and contract personnel (V11) Year 1 (RM) Year 2 (RM) Year 3 (RM) Year 4 (RM) ,9 42,75 13,5 Total (RM) 6,15 Travel and transportation (V21) 8, 28, 36, Rentals (V24) Research materials and supplies (V26) 28,5 2, 1,5 32, Minor modifications and repairs (V28) 5, 5, 1, Special services (V29) 15, 2, 17, Special equipment and accessories (V35) 45, 45, Total direct 77,4 72,75 5, 2,15 C. Total project cost Year 1 (RM) Year 2 (RM) Year 3 (RM) Year 4 (RM) Total (RM) 82,71 14,31 62,98 25, in Improved Page 16 of 18

18 Summary of Project Funding A. Funding Sources Funding Sources RM % of Total Funding Science Fund 2, % Internal Fund 49, % Other Sources Total Funding 25,. % 1 % B. Disbursement schedule for ScienceFund, by participating research organisation Organisation Year 1 (RM) Year 2 (RM) Year 3 (RM) Year4 (RM) Total (RM) Universiti Teknologi Malaysia 77,4 72,75 5, 2,15 Total ScienceFund 77,4 72,75 5, 2,15 in Improved Page 17 of 18

19 CONTRACTUAL MATTERS A. Contractual obligations under this project None B. Ownership of intellectual property rights UTM - Universiti Teknologi Malaysia in Improved Page 18 of 18