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Recrystallization of a Single Crystal Nickel-Base Superalloy 总被引:2,自引:0,他引:2
A series of experiments of investigating the recrystallization of single crystal DD3 superalloy were carried out. The threshold temperature for recrystallization and the effect of annealing temperature on recrystallization were studied. The results show that the threshold temperature for recrystallization of the shot peened DD3 samples is between 1 000 ℃ and 1 050 ℃ under the condition of annealing for 2 h, and the recrystallization depth increases with the rise of the annealing temperature. Below 1 150 ℃, the recrystallization depth increases slowly with the temperature climbing, while above 1 150 ℃, the recrystallization depth increases quickly with the rise of the temperature. The solution of the γ′ phase is a critical factor of the recrystallization behavior of DD3 superalloy. In addition, the kinetics and microstructural evolution of recrystallization at 1 200 ℃ were also studied. It is found that the recrystallization progresses rapidly at 1 200 ℃ through the growth of fully developed recrystallized grains, and the recrystallization process on the shot peened surface is similar to that of wrought materials, including nucleation of recrystallization, growth of new grains into the matrix, and growth of new grains by swallowing up each other. 相似文献
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R. L. Cairns 《Metallurgical and Materials Transactions B》1974,5(7):1677-1684
Dispersion strengthened nickel-base superalloy bar has been produced by hot extrusion of mechanically alloyed powders. The
fabrication methods produce an ultra-fine grained material which resists grain growth up to a critical temperature around
1506K (2250°F). Above this temperature, a discontinuous grain growth process leads to the formation of coarse elongated macrograins.
The material becomes completely coarse grained in short times. Annealing below this temperature produces only slight grain
coarsening, and relieves stored strain energy. Changes in properties are related to the grain growth and strain annealing
processes. 相似文献
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K. Murakami K. Mino H Harada H. K. D. H. Bhadeshia 《Metallurgical and Materials Transactions A》1993,24(5):1049-1055
The recrystallization behavior of mechanically alloyed and extruded MA6000 oxide dispersion strengthened (ODS) nickel-base
superalloy has been studied as a function of the position of the sample in the extruded bar. It was found that there are profound
differences across the cross section of the bar, the edge regions recrystallizing more easily relative to the core. Furthermore,
the recrystallized grains tend to be much more anisotropic at the edges. It appears that these differences are caused by inhomogeneous
deformation. The oxide particles are more aligned along the extrusion direction at the regions near the surface, presumably
because of the more extensive deformation in those regions. This explains the greater anisotropy in the recrystallized grains
and the relative case of recrystallization (since the boundary mobility along the extrusion direction is high for aligned
particles). Stored energy measurements confirm that the observed effects cannot be explained by differences in the driving
force for recrystallization.
Formerly Senior Researcher, Research Development Corporation of Japan 相似文献
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Recrystallization of Single Crystal Nickel-Based Superalloy 总被引:1,自引:0,他引:1
A series of experiments of investigating the recrystallization of single crystal DD3 superalloy were carried out. The threshold temperature for recrystallization and the effect of annealing temperature on recrystaUization were studied. The results show that the threshold temperature for recrystallization of the shot-peened DD3 samples is be-tween 1 000 ℃ and 1 050℃ under the condition of annealing for 2 h, and the recrystallization depth increases with the rise of the annealing temperature. Below 1 150 ℃, the recrystallization depth increases slowly with the tempera-ture climbing, while above 1 150 ℃, the recrystallization depth increases quickly with the rise of the temperature. The solution of the γ' phase is a critical factor of the recrystallization behavior of DD3 superalloy. In addition, the ki-netics and microstructural evolution of recrystallization at 1 200 ℃ were also studied. It is found that the recrystalli-zation progresses rapidly at 1 200℃ through the growth of fully developed recrystallized grains, and the recrystalli-zation process on the shot-peened surface is similar to that of wrought materials, including nucleation of reerystalliza-tion, growth of new grains into the matrix, and growth of new grains by swallowing up each other. 相似文献
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Shot peening involves bombarding the surface of a metal part with small spherical media called shot. It creates a uniform layer of compressive residual stress at surfaces and considerably increases the part life. This study is devoted to an evaluation of the edge (corner) effects in the shot peening process. Geometry variations in metal parts such as edges or corners cause variance in the residual stress profile induced by shot peening. This paper presents the finite-element modeling and scheme that we use to simulate the shot peening process by both single impact and multiple impacts for part geometries with different edge radii. The results achieved show that, after the same shot peening process, a part with a relatively larger edge radius results in a satisfactory residual stress profile which could equal or exceed that expected for a part with a smaller edge radius. The results may enable the automated edge preprocess step for shot peening with an easily machined large radius to reduce cost and improve productivity. 相似文献
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Using a new system shot peening and/or stress peening in an air blast machine at elevated temperatures is feasible. The effects of conventional shot peening, stress peening, warm peening and stress peening at elevated temperatures on the characteristics of regions close to the surface, on the stability of residual stresses and on the fatigue strength of a quenched and tempered AISI 4140 steel (German grade 42 CrMo 4) are presented. The alternating bending strength is increased by stress peening, warm peening and especially the combination of both compared to conventional shot peening. These effects are due to the residual stresses induced and the stability of the dislocation structure, which is highly affected by strain ageing effects. 相似文献
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The evolution of the microstructure and the properties of an austenitic high-manganese steel subjected to severe deformation by cold rolling and subsequent recrystallization annealing is investigated. Cold rolling is accompanied by mechanical structural twinning and shear banding. The microhardness and microstructural analysis of annealed samples are used to study the recrystallization kinetics of the high-manganese steel. It is shown that large plastic deformation and subsequent annealing result in rapid development of recrystallization processes and the formation of an ultrafine-grained structure. A completely recrystallized structure with an average grain size of 0.64 μm forms after 30-min annealing at a temperature of 550°C. No significant structural changes are observed when the annealing time increases to 18 h, which indicates stability of the recrystallized microstructure. The steel cold rolled to 90% and annealed at 550°C for 30 min demonstrates very high strength properties: the yield strength and the tensile strength achieve 650 and 850MPa, respectively. The dependence of the strength properties of the steel on the grain size formed after rolling and recrystallization annealing is described by the Hall–Petch relation. 相似文献