Effect of grit blasting and subsequent heat treatment on stress rupture property of a Ni-based single-crystal superalloy
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Effect of grit blasting and subsequent heat treatment on stress rupture property of a Ni‑based single‑crystal superalloy SGX3 Jinshan He1 · Zhengrong Yu2 · Longfei Li2 · Xitao Wang1,3 · Qiang Feng2 Received: 26 December 2019 / Revised: 29 January 2020 © The Chinese Society for Metals (CSM) and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In the present study, the effect of grit blasting and subsequent heat treatment on the stress rupture properties of a thirdgeneration nickel-based single-crystal superalloy SGX3 sheet was studied. It was found that the stress rupture life of alloy SGX3 sheet at 980 °C/250 MPa was reduced by about 60% by only vacuum heat treatment at 1100 °C for 200 h and further reduced by 20% and 70% respectively with grit blasting of 0.3 MPa/1 min and 0.5 MPa/2 min before heat treatment. The microstructure analysis results indicated that the degradation of stress rupture life of alloy SGX3 sheet by vacuum heat treatment was mainly attributed to the variation of γ/γ′ microstructure, i.e., the decrease in γ′ volume fraction and the coarsening of γ′ precipitates. Furthermore, such degradation by grit blasting and subsequent vacuum heat treatment should be attributed to the formation of cellular recrystallization with different thicknesses at the surface of alloy SGX3 sheet, which not only acts as the vulnerable site for cracks to initiate and propagate but also reduces the effective loading area. Keywords Ni-based single-crystal superalloy · Creep life · Degradation · Recrystallization
1 Introduction Ni-based superalloys are often used for high-pressure turbine blades of advanced aero engines [1–5]. Among these, singlecrystal alloys have been introduced due to their excellent high-temperature mechanical properties by eliminating grain boundaries [3, 6]. Both thermal stress by temperature gradient during casting and mechanical stress caused by surface processing such as shot peeing or grit blasting lead to the Available online at https://link.springer.com/journal/40195. * Longfei Li [email protected] 1
Beijing Advanced Innovation Center for Material Genome Engineering, Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China
2
Beijing Advanced Innovation Center for Material Genome Engineering, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
3
Shandong Provincial Key Laboratory for High Strength Lightweight Metallic Materials, Advanced Materials Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
local plastic deformation [7–9]. At those sites, the equiaxed recrystallization can occur when Ni-based single-crystal superalloy is further heat-treated at solution temperature [10, 11]. As a result, the transverse grain boundaries introduced by recrystallization lead to the degradation of creep property of Ni-based single-crystal superalloy. Jo et al. reported that the recrystallize
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