Fracture mechanics approach to creep growth in welded IN738LC gas turbine blades
- Gas and Steam Turbine Engineering Dept., Power Generation Technology Div., Westinghouse Canada Inc., Hamilton, Ontario (CA)
Microcracks caused by hot cracking or strain age cracking mechanisms are very likely to be discovered in the weld repair zone of precision-cast IN738LC gas turbine blades. The possibility of crack propagation under the operating conditions of the gas turbine thereby becomes a crucial issue for gas turbine designers. The creep crack growth rate in air of the hipped and fully heat-treated IN738LC was measured at the service temperature experienced by the first-stage turbine blade tip. The corresponding growth behavior was also studied. The creep crack growth rate, da/dt, versus crack tip stress intensity factor, K{sub I}, a relation that exhibits the typical primary, secondary, and tertiary behavior, supports the applicability of K{sub I} as an appropriate correlating parameter for the creep crack growth of this Ni-based superalloy under the loading conditions use din this study. In this paper microstructural examination illustrates that the creep crack growth of IN738LC principally takes place by the nucleation, growth, coalescence, and link-up of grain boundary microvoids and microcracks. An excellent approximation of the stress intensity factor under service loading conditions in the vicinity of the crack tip is obtained by using the Westinghouse WECAN finite element analysis. It is shown that the crack tip stress intensity factor under normal loading conditions will not be able to drive the transverse through-the-wall thickness blade tip crack in this study.
- OSTI ID:
- 5200415
- Journal Information:
- Journal of Engineering for Gas Turbines and Power; (United States), Vol. 114:2; ISSN 0742-4795
- Country of Publication:
- United States
- Language:
- English
Similar Records
Interaction between oxidation and thermo-mechanical fatigue in IN738LC superalloy--I
An Innovative Technique for Evaluating the Integrity and Durability of Wind Turbine Blade Composites
Related Subjects
GAS TURBINES
CRACK PROPAGATION
TURBINE BLADES
CREEP
COALESCENCE
CRACKS
FINITE ELEMENT METHOD
FRACTURE MECHANICS
GRAIN BOUNDARIES
HEAT TREATMENTS
METALLOGRAPHY
NICKEL BASE ALLOYS
NUCLEATION
STRAINS
STRESS INTENSITY FACTORS
THICKNESS
WELDING
ALLOYS
CRYSTAL STRUCTURE
DIMENSIONS
EQUIPMENT
FABRICATION
JOINING
MACHINERY
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
NICKEL ALLOYS
NUMERICAL SOLUTION
TURBINES
TURBOMACHINERY
330103* - Internal Combustion Engines- Turbine