0
Research Papers: Gas Turbines: Structures and Dynamics

Mechanical Behavior of Dissimilar Welds for Steam Turbine Rotors With High Application Temperature

[+] Author and Article Information
Stefan Krojer

Materials Testing Institute (MPA),
University of Stuttgart,
Pfaffenwaldring 32,
Stuttgart 70569, Germany
e-mail: stefan.krojer@mpa.uni-stuttgart.de

Eberhard Roos

Professor
Materials Testing Institute (MPA),
University of Stuttgart,
Pfaffenwaldring 32,
Stuttgart 70569, Germany
e-mail: eberhard.roos@mpa.uni-stuttgart.de

Andreas Klenk

Materials Testing Institute (MPA),
University of Stuttgart,
Pfaffenwaldring 32,
Stuttgart 70569, Germany
e-mail: andreas.klenk@mpa.uni-stuttgart.de

Shilun Sheng

Siemens AG, Energy Sector,
Rheinstraße 100,
Mülheim an der Ruhr 45478, Germany
e-mail: shilun.sheng@siemens.com

Torsten-Ulf Kern

Siemens AG, Energy Sector,
Rheinstraße 100,
Mülheim an der Ruhr 45478, Germany
e-mail: torsten-ulf.kern@siemens.com

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 23, 2014; final manuscript received July 29, 2014; published online October 7, 2014. Editor: David Wisler.

J. Eng. Gas Turbines Power 137(3), 032511 (Oct 07, 2014) (8 pages) Paper No: GTP-14-1429; doi: 10.1115/1.4028435 History: Received July 23, 2014; Revised July 29, 2014

Fossil fired steam power plants of the latest generation require the elevation of steam parameters pressure and temperature to increase efficiency as well as to reduce greenhouse gas emissions. In order to achieve these goals for high temperatures, nickel-base alloys could play an important role for steam turbine applications in the future. Due to technological and economical restrictions, their application in turbine rotors shall be restricted to the most heavily stressed regions. Dissimilar welds offer a known solution to combine nickel-base alloys with ferritic/martensitic steels in this case. Thermal mismatch and differences in high temperature performance of the applied base materials make it very difficult to evaluate the lifetime of such dissimilar welds. Depending on temperature and type of loading, different failure mechanisms can be observed. Further, the type of weld material plays a major role for the service behavior of the weld. Therefore, this paper describes standard creep and fatigue tests which were conducted to identify failure mechanisms and failure locations at the weld zone. To simulate the outcome of the creep tests, a modified Graham-Walles approach is used that also accounts for the different creep behavior of the heat affected zones (HAZs) compared to the base material. For the simulation of the fatigue tests, the model type Chaboche–Nouailhas–Ohno–Wang (CNOW) is used. The results contribute to better knowledge in designing dissimilar welds between nickel-base alloys and martensitic steels under high temperature loading.

Copyright © 2015 by ASME
Your Session has timed out. Please sign back in to continue.

References

Strauß, K., 2009, Kraftwerkstechnik, Springer, Berlin, Germany.
Granacher, J., Tscheuschner, R., Maile, K., and Eckert, W., 1993, Langzeitiges Kriechrissverhalten kennzeichnender Kraftwerksstähle2, VCH Verlagsgesellschaft mbH, Materialwissenschaft und Werkstofftechnik, Weinheim, Germany, 24, pp. 367–377.
Bareiß, J., Nothdurft, R., Kurtz, M., Helmrich, A., Hartwig, R., and Bantle, M., 2009, “Materials Specification VGB-R 109 and Processing Standards—First Experiences of a Large-Scaled Power Plant for Quality Control Purposes,” 35th MPA-Seminar, Stuttgart, Germany.
Lückemeyer, N., Kirchner, H., Kern, T.-U., Reigl, M., Klenk, A., Klein, T., Schwienheer, M., Cui, L., Scholz, A., and Berger, C., 2010, “Determination of Material Behavior in 700 °C Turbine Components Under Component and Load Specific Conditions,” 36th MPA-Seminar, Stuttgart, Germany.
Gierschner, G., Ullrich, C., Tschaffon, H., and Hansknecht, F., 2012, “Latest Developments for the Flexible High Efficient Power Plant of the Future,” 38th MPA-Seminar, Stuttgart, Germany.
Heinrich, H., 1991, Warmfeste Stähle in Kraftwerken, Essen, Germany, pp. 55–59.
Kautz, H., 1996, Das neuzeitliche Kohlekraftwerk, Expert Verlag, Renningen-Malmsheim, Germany.
Abe, F., 2012, “Effect of Boron on Long-Term Stability of 9Cr Steel for 650 °C Boilers,” 38th MPA-Seminar, Stuttgart, Germany.
Kern, T.-U., Mayer, K. H., Donth, B., Zeiler, G., and DiGianfrancesco, A., 2010, “The European Efforts in Development of New High Temperature Rotor Materials—COST536,” 9th Liége Conference, Liége, Belgium, Sept. 27–29, pp. 29–38.
Danielsen, H. K., di Nunzio, P. E., and Hald, J., 2012, “Kinetics of Z-Phase Precipitation in 9–12 pct Cr Steels,” Metall. Mater. Trans. A, 44A(5), pp. 2245–2252. [CrossRef]
Moon, D. P, Simon, R. C., and Favor, R. J., 1968, “The Elevated-Temperature Properties of Selected Superalloys,” ASTM Data Series DS 7 S1, Alpha, NJ, pp. 163–172.
Sims, C. T., Stoloff, N. S., and Hagel, W. C., 1987, Superalloys II, Wiley, Hoboken, NJ.
Pollock, T. M., and Tin, S., 2006, “Nickel-Based Superalloys for Advanced Turbine Engines: Chemistry, Microstructure, and Properties,” J. Propul. Power, 22(2), pp. 361–374. [CrossRef]
Lückemeyer, N., 2012, “Strukturmechanische Auslegungskonzepte für Großkomponenten einer 700 °C Dampfturbine,” Ph.D. dissertation, Universität Stuttgart, Stuttgart, Germany.
Pohle, C., 1999, Schweißen von Werkstoffkombinationen, Verlag für Schweißen und verwandte Verfahren DVS-Verlag, Düsseldorf, Germany.
Bürgel, R., 2011, Handbuch Hochtemperatur-Werkstofftechnik, Friedrich Vieweg & Sohn Verlag, Wiesbaden, Germany.
Deutscher Verband für Schweißen und verwandte Verfahren e.V., 2000, Schweißen von Schwarz-Weiß-Verbindungen (S/W-Verbindungen), Merkblatt DVS 3011, DVS Media GmbH, Düsseldorf, Germany.
Bauer, M., 2009, “Lebensdaueroptimierung von Schweißverbindungen martensitischer Stähle für Hochtemperaturanwendungen,” Ph.D. dissertation, Universität Stuttgart, MPA Stuttgart, Stuttgart, Germany.
Dilthey, U., 2005, Schweißtechnische Fertigungsverfahren, Band 2: Verhalten der Werkstoffe beim Schweißen, Springer, Berlin, Germany.
Klenk, A., Feuillette, C., Klein, T., and Maile, K., 2011, “Studies on the Behaviour of Heat Affected Zones in 9-10Cr Steels and Their Influence on Stress State in Components,” 37th MPA-Seminar, Stuttgart, Germany.
Schubert, J., Klenk, A., and Maile, K., 2005, “Determination of Weld Strength Factors for the Creep Rupture Strength of Welded Joints,” ECCC Conference Creep and Fracture in High Temperature Components—Design and Life Assessment Issues, London, UK, Sept. 12–14, pp. 791–805.
Schmidt, K., 2013, “Komponentenverhalten im 700 °C-Kraftwerk—Numerische und experimentelle Untersuchungen,” Ph.D. dissertation, Universität Stuttgart, MPA Stuttgart, Stuttgart, Germany.
Mayr, P., 2007, “Evolution of Microstructure and Mechanical Properties of the Heat Affected Zone in B-Containing 9% Chromium Steels,” Ph.D. dissertation, TU Graz, Institut for Materials Science, Welding and Forming, Graz, Austria.
VDM Metals, 2014, “VDMR Alloy 625 (Nicrofer 6020 hMo),” VDM Metals GmbH, Werdohl, Germany, available at: http://www.vdm-metals.com/de/downloads/data-sheets/
Special Metals Corporation, 2006, Inconel Alloy 625, SMC, New Hartford, NY.
Rauch, M., 2006, “Entwicklung eines Lebensdauerkonzeptes für Schaufel-Welle-Verbindungen stationärer Turbinen aus Nickelbasis- und 10%-Chromlegierungen,” Ph.D. dissertation, Universität Stuttgart, MPA Stuttgart, Stuttgart, Germany.
Ringel, M., Roos, E., Maile, K., and Klenk, A., 2004, “Advanced Constitutive Equations for 10 Cr Forged and Cast Steel for Steam Turbines Under Creep Fatigue and Thermo-Mechanical Fatigue,” 30th MPA Seminar, Stuttgart, Germany, Oct. 6–8.

Figures

Grahic Jump Location
Fig. 1

Texture of the HAZ including the fusion line, after [19]

Grahic Jump Location
Fig. 2

Weld strength factors for similar welds [20,21]

Grahic Jump Location
Fig. 3

Specimen position across the weld: (a) center line = weld metal center position and (b) center line = fusion line at 10Cr side

Grahic Jump Location
Fig. 4

Comparison of creep rupture behavior

Grahic Jump Location
Fig. 5

Creep rupture deformation behavior at a high stress level: (a) 550 °C and (b) 600 °C

Grahic Jump Location
Fig. 6

Creep rupture deformation behavior at a low stress level: (a) 550 °C and (b) 600 °C

Grahic Jump Location
Fig. 7

Creep rupture deformation behavior of matched welds: (a) high stress level and (b) low stress level

Grahic Jump Location
Fig. 8

Creep deformation over time at 550 °C

Grahic Jump Location
Fig. 9

Gauge position for LCF-tests

Grahic Jump Location
Fig. 10

Crack initiation curves for 450 °C and 550 °C with trend line

Grahic Jump Location
Fig. 11

Evolution of the maximum LCF stress ratio

Grahic Jump Location
Fig. 12

Formation of microcracks in matched welds

Grahic Jump Location
Fig. 13

Formation of microcracks in mismatched welds: (a) fusion line mechanism and (b) mixed mechanism

Grahic Jump Location
Fig. 14

Comparison FE versus experiment, 550 °C

Grahic Jump Location
Fig. 15

Deformation response of mismatched creep specimens, 550 °C

Grahic Jump Location
Fig. 16

Stress concentration on the surface at the fusion line of matched creep specimen, no stress concentration for the mismatched specimen

Grahic Jump Location
Fig. 17

Schematic CLCF-preprogram

Grahic Jump Location
Fig. 18

Equivalent strain distribution at 550 °C and high strain amplitude of matched welds

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In