Abstract
DZ417G is a directionally solidified (DS) superalloy developed for low-pressure blade applications in gas turbine engines. The crystallization microstructures of DZ417G samples caused by sand-blasting and machining were investigated. The tensile properties of the alloy after crystalliza- tion were tested at room temperature and 900 and its stress-rupture performance was examined under conditions of 980 /216 MPa and 760 /725 MPa. The results show that after solution treat- ment equiaxed recrystallization grains form on the surface of specimens machined from directionally solidified alloy bars. After aging treatment, cellular recrystallization takes place on the surface of spec- imens pretreated by sand blasting. Both the yield strength and tensile strength at room temperature decrease after recrystallization, while those at 900 are slightly affected by recrystallization. The recrystallization depth increases after stress-rupture tests, which may be attributed to migration of recrystallization boundaries driven by high temperature and stress. For samples without recrystalliza- tion microstructure, the fracture mode is transgranular, which is controlled by the propagation rate of the cracks initiated both on surface and at inner microstructure discontinuities. While for samples with recrystallization microstructure, the cracks prefer to be initiated on transverse recrystallization grain boundaries and propagate along the recrystallization boundaries into the matrix, which may accelerate the propagation rate. TRF (transverse recrystallization area fraction) is a factor to evaluate the effect of recrystallization on the stress-ruptured performance. The stress-ruptured performance is decreased with the increase of TRF between 0 and 0.5. For samples with a TRF of 0.5, second cellular recrystallization forms in the first equiaxed recrystallization grain. The cracks initated at interfaces of cellular microstructure have a high density, which impair the stress-ruptured performance of DZ417G alloy.
Paper version not known (
Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
