RAISELIFE Dissemination Workshop, Madrid, 17 th of May 2017

Transcription

1 Mechanical tests in liquid molten salts 17 th of May 2017, Madrid, J. Preußner, W. Pfeiffer, E. Piedra, S. Oeser, M. Tandler, P. von Hartrott, G. Maier Slide 1

2 Content Mechanical tests - overview Mechanical tests in molten salts Summary on static corrosion tests SSRT LCF Summary Slide 2

3 Lifetime Concepts, Thermomechanics Field of work Testing and assessment of materials advanced lifetime concepts component assessment testing microstructure damage mechanisms assessment Damage mechanisms (short) crack growth microstructure degradation brittle fracture environmental influence visoplastic models finite element method postprocessing Slide 3

4 stress in MPa stress in MPa RAISELIFE Dissemination Workshop, Madrid, 17 th of May 2017 Time and temperature dependent plasticity Adjustment of the Chaboche-model loading history 300 C 950 C Strain rate 1e-3 1/s 1e-4 1/s 1e-5 1/s holdtime stress in MPa stress in MPa Strain Time in s time in s time in s Example: Nickelbase alloy MAR-M247 strain strain Slide 4

5 Lifetime Concepts, Thermomechanics Typical materials Aluminium Ferrite, Perlite, Martensite Sheet metals Cast alloys Forged materials AlSi for pistons AlSi for cylinderheads , , GJL:150, 250, 300 GJV: 450 GJS: 400, 500, 700 GJS SiMo: SiMoNi, SiMo1000, SiMoCr, SiMo51 G-X12CrMoWVNbN G-X12CrMoVNbN9-1 G-X12CrMoCoVNbB9-1 Austenite , , , , Alloy800H Nickelbase Alloy740, C263 Internal combustion engines/automotive KN2, D5S, , , A3K, A5N, MAR-M247, C1023, MAR-M246, IN100, IN713, IN738 Power generation Plant engineering , 5083 X12CrMoWVNbN X12CrMoVNbN9-1 X12CrMoCoVNbB T/P91 T/P92 T/P23 T Alloy 800 Alloy617/Alloy617B C263, IN718, Allvac718Plus Turbine applications Slide 5

6 Retrofit for improved flexibility Header, TMF C, 295 bar 600 C 300 C 295 bar 1 bar t 1 t 2 t 3 Slide 6 Alloy 617B Wall thickness = 30 mm Heating time = 10 mins Martensitic steel Wall thickness = 45 mm Heating time = 60 mins N f = N f =

7 Mechanical tests in liquid molten salts J. Preußner, W. Pfeiffer, E. Piedra, S. Oeser, M. Tandler, P. von Hartrott, G. Maier Slide 7

8 Materials 60% NaNO 3 and 40% KNO 3 Slide 8

9 Static corrosion tests Immersion temperature salt composition steel composition Significant effect on oxide formation observed for Steel composition Salt composition Immersion temperature Corrosion curves (weight gain) for different temperatures, salt purity grades and steels; ind indicates industrial grade salt and ref refined grade salt. Slide 9

10 Mechanical tests in molten salt Slow strain rate test in molten salt Here: Flat or round samples LCF testing in molten salt Here: Tube sample Slide 10

11 Stress corrosion cracking tensile stress SCC corrosive medium susceptible material Slide 11

12 Slow strain rate tests (SSRT) Nb stab. (air) 347 Nb stab. (salt) Ductile failure in both samples Slide 12

13 Microstructure of 347 SSRT Samples Microstructure and core hardness in clamping area (163 3) HV1 (198 3) HV1 (210 5) HV1 initial microstructure 550 C, air (782 h) 550 C, salt (530 h) microstructure changes during test Slide 13

14 Depth profiles of elements GD-OES SSRT, 550 C, air, 782 h SSRT, 550 C, Salt, 530h more nitrogen in surface near area of samples tested in salt Slide 14

15 Hardness measurements on 347 Nb. stab SSRT samples F max = 5 mn (loading and unloading 5 mn/10 s, dwell time at F max 10 s); HV calculated fromh IT (measured in clamp area) hardening of the surface of sample testet in salt Slide 15

16 stress [MPa] RAISELIFE Dissemination Workshop, Madrid, 17 th of May 2017 LCF-tests with Sanicro 25 tube samples Result h P1 5,6 P2 7,9 P3 13,5 P4 12,8 P5 132,2 strain Slide 16

17 LCF results on Sanicro 25 tube samples Fracture surfaces P1 (air) P2 (salt) Both samples show same fracture mechanisms and also same width of striations (here approx. 300µm from crack origin) Slide 17

18 Conclusion SSR tests and LCF tests in salt were performed no severe influence of salt on 347 in SSRT the microstructure changes during the test due to (possible) nucleation and coarsening of carbides. nitrogen diffuses into the samples tested in salt which changes the surface properties The LCF tests at air and in molten salt atmosphere with Sanicro 25 show similar results. No evidence for stress corrosion cracking could be found in the tests. However, the test times chosen were relatively short Slide 18

19 End Slide 19

20 Ongoing work Longer test times (slow strain rate tests) within EU project RAISELIFE T91, VM12-SHC, Alloy 617 Flow accelerated tests / SSRT T91, VM12-SHC, Alloy 617 weldments coatings Modeling? [U.Krupp 2004] Slide 20

21 Coatings Coated side Steel substrate Uncoated side Oxide layers NiAl coated P h, 565 C hot salt melt Embedding Material Slide 21

22 Sample geometries Flat sample Tube sample Slide 22

23 Advanced corrosion tests HT-corrosion with thermal cycling HT-corrosion with quasi-static mechanical load HT-corrosion with cyclic mechanical load HT-corrosion with abrasive wear Slide 23