Thermal fatigue behavior of a nickel-base single crystal superalloy DD5 with secondary orientation

Lv, Jinjuan; Wang, Andong; Chen, Caifeng; Xu, Weitai; Zhang, Luxiang

doi:10.1088/2053-1591/aadac7

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…These variations lead to different levels of local resolved shear stress on slip systems (Figures 7 and 8), which in turn give rise to the excitation of different types of dislocations, contributing to the secondary orientation effect. Earlier research reported that for the (010) orientation, cracks grow slower than that for the (110) orientation [18], whereas in the current research, the trend seems to be reversed, as for the (110) orientation, a crack of ~20 µm was observed after 80 cycles (Figure 3) compared to the crack of ~130 µm for the (010) orientation (Figure 2). Note that the current tests were conducted at a lower temperature and that temperature is known to affect the fracture mode [17].…”

Section: Discussioncontrasting

confidence: 68%

“…Both the (010) and (110) samples demonstrate an exponential decay of stresses away from the notch, as evidenced by Figure 5 a,b, and the stress tensor components vary between the two orientations. These variations arise from anisotropy of the elastic constants to which thermal stress is directionally proportional [ 18 ]. These variations lead to different levels of local resolved shear stress on slip systems ( Figure 7 and Figure 8 ), which in turn give rise to the excitation of different types of dislocations, contributing to the secondary orientation effect.…”

Section: Discussionmentioning

confidence: 99%

“…The crack propagation mode was found to be sensitive to temperature, with a switch from interdendritic propagation to crystallographic propagation along the (111) plane with increasing temperature in a DZ444 nickel base superalloy [17]. The crack growth dynamics were found to be affected by secondary orientations [18,19] with [100] orientations more resistant to crack growth compared with 2 of 17 [110] orientations, and the crack growth rates of the two orientations were both accelerated at higher temperatures.…”

Section: Introductionmentioning

confidence: 99%

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A Study of the Internal Deformation Fields and the Related Microstructure Evolution during Thermal Fatigue Tests of a Single-Crystal Ni-Base Superalloy

Zong,

Liu,

et al. 2024

Materials

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Ni-base superalloys operate in harsh service conditions where cyclic heating and cooling introduce deformation fields that need to be investigated in detail. We used the high-angular-resolution electron backscatter diffraction method to study the evolution of internal stress fields and dislocation density distributions in carbides, dendrites, and notch tips. The results indicate that the stress concentrations decay exponentially away from the notch, and this pattern of distribution was modified by the growth of cracks and the emission of dislocations from the crack tip. Crack initiation follows crystallographic traces and is weakly correlated with carbides and dendrites. Thermal cycles introduce local plasticity around carbides, the dendrite boundary, and cracks. The dislocations lead to higher local stored energy than the critical value that is often cited to induce recrystallization. No large-scale onset of recrystallization was detected, possibly due to the mild temperature (800 °C); however, numerous recrystallized grains were detected in carbides after 50 and 80 cycles. The results call for a detailed investigation of the microstructure-related, thermally assisted recrystallization phenomenon and may assist in the microstructure control and cooling channel design of turbine blades.

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Section: Discussioncontrasting

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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