Evaluating Single Crystal Ni-base Superalloys - UTSR Summer Report 2012 Phillip Draa Siemens Energy Products Gas Turbines Copyright Siemens 2012
Background Ni- base superalloys are used in the hot section of gas turbines. Single crystal superalloys have been used in the aerospace industry for many years. Recently, the metallurgical demands of industrial gas turbines (IGT) have increased and the use of single crystals is being considered. IGT components are much larger than their aerospace counterparts and require different metallurgical concerns. Thomas-Sourmail Red: Ni-base Superalloys Orange: Steels Blue: Ti-alloys Page 2 Aug 2012 GT EN
Alloy Evaluation Mechanical Properties Physical Properties Castability Machinability Material Selection Microstructure Oxidation Properties Cost Page 3 Aug 2012 GT EN
Alloy Background Rolls-Royce, The Jet Engine, 4th edn. Three alloys were chosen for study as use in the first row of a new engine design: CMSX-486, PWA1484 and CMSX-8 (B/C) CMSX-486 is the most economically priced of the three and does not require a solution heat treatment. PWA1484 is a 2 nd generation alloy with good mechanical and oxidation properties. CMSX-8 (B/C) is a low-rhenium alloy that has similar properties to CMSX-4. Page 4 Aug 2012 GT EN
Mechanical and Physical Properties Mechanical testing was completed for many different properties. The data was statistically analyzed and design curves were generated. Estimated properties for alloys that have not been tested yet were generated using literature data. Example of literature data Page 5 Aug 2012 GT EN
Heat Treatment What can we do to advantageously and economically change the microstructure of our as-cast components? PWA1484 CMSX-486 CMSX-8 B/C Page 6 Aug 2012 GT EN
Incipient Melting Incipient melting should be avoided. Porosity can be an indication of melting. PWA1484 showing a mix of casting porosity and incipient melting. CMSX-486 Page 7 Aug 2012 GT EN
Incipient Melting/Porosity Percentages Alloy Temperature, C Average %Vf of Incipient Melting/Porosity CMSX- 486 As-Cast 0.01 CMSX- 486 1230 0.21 CMSX- 486 1240 0.46 CMSX- 486 1250 0.69 CMSX- 486 1260 1.00 CMSX- 486 1270 2.22 PWA1484 As-Cast 0.06 PWA1484 1300 0.24 PWA1484 1310 0.26 PWA1484 1320 0.29 PWA1484 1330 0.33 CMSX-8 (B/C) As-Cast 0.05 Page 8 Aug 2012 GT EN
Gamma Prime Solutioning Take the microstructure from: To this: PWA1484 *Avoiding creation of incipient melting porosity. Page 9 Aug 2012 GT EN
Gamma Prime and Porosity Analysis Technique For PWA1484 using the PAXIT software. Able to measure the remaining eutectic phase, as well as undissolved gamma prime. Sample ID Avg % Eutectic Avg % Undissolved γ' Total Avg % Unsolutioned 153987 2.32 1.97 4.29 153988 1.57 0.91 2.48 153989 1.02 1.67 2.69 153990 0.29 0.23 0.52 153991 2.65 2.16 4.81 153992 1.44 0.90 2.34 153993 1.38 0.60 1.98 153994 0.88 0.49 1.37 Similar measurements can be made for the low contrast porosity. Page 10 Aug 2012 GT EN
Conclusions/Future Work CMSX-486 was rejected for its inability to solution and any possible rejuvenation. Component designers are able to start work using curves for the new alloys. Continue decreasing the total heat treatment time. Validate design curves with continued testing. Test other properties Page 11 Aug 2012 GT EN
Site Visit Lakeland Page 12 Aug 2012 GT EN
Manufacturing Plant Visit Gray Construction http://www.gray.com/sites/default/files/projects/siemans_gas_turbine_040.jpg Industrial Gas Turbine part manufacture and assembly site Page 13 Aug 2012 GT EN
Acknowledgments Special Thanks to: Allister James, Cynthia Klein, Ray Snider and Sachin Shinde Siemens Employees in Orlando and Charlotte SWRI and the UTSR Fellowship Committee Page 14 Aug 2012 GT EN
Questions? Thank You! Page 15 Aug 2012 GT EN