Effects of cycle type and coating on the TMF lives of a single crystal nickel based gas turbine blade alloy

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:531469

Bressers, J; Timm, J ^[1]; Williams, S J; Bennett, A ^[2]; Affeldt, E E ^[3]

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1. Joint Research Centre, Petten (Netherlands). Inst. for Advanced Materials
2. Rolls-Royce plc, Derby (United Kingdom)
3. Motoren und Turbinen Union Muenchen (Germany)

Strain controlled thermo-mechanical fatigue cycles simulating the temperature-strain-time history at critical locations of blades of advanced aero gas turbines are applied to the single crystal nickel based alloy SRR99 in the uncoated and aluminide coated conditions. The TMF cycle selection includes a {minus}135{degree} lag cycle and an in-phase cycle, with various R-ratios, T{sub min} = 300 C, and T{sub max} = 1,050 C and 850 C, respectively. The cycle-specific stress response is analyzed and discussed in terms of the accumulation of inelastic strain during the TMF tests, and the inelastic strain build-up is correlated with the cyclic hardening/softening behavior. The number of cycles for initiating microcracks is measured by means of a computer vision system. Various modes of crack initiation and crack growth are observed and correlated with the TMF cycle type, with the strain range imposed, and with the ductile/brittle behavior of the coating. The differences in TMF lives are discussed in terms of the material and TMF parameters.

• OSTI ID: 531469
• Report Number(s): CONF-941159--; ISBN 0-8031-2001-X
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
COATINGS
CRACK PROPAGATION
FATIGUE
GAS TURBINE ENGINES
HEAT RESISTING ALLOYS
MONOCRYSTALS
NICKEL BASE ALLOYS
SERVICE LIFE
TURBINE BLADES