高合金化GH4151合金复杂析出相演变行为

As-cast microstructure characteristic and homogenization of a newly developed hard-deformed Ni-based superalloy GH4975

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难变形高温合金GH4975的铸态组织及均匀化

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Research on hot deformation behavior and microstructure-properties control of GH4151 alloy

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GH4151合金高温变形行为及组织与性能控制研究

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Recent development of nickel-based disc alloys and corresponding cast-wrought processing techniques

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变形高温合金盘材及其制备技术研究进展

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Superplastic deformation and dynamic recrystallization of a novel disc superalloy GH4151

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The superplastic deformation of a hot-extruded GH4151 billet was investigated by means of tensile tests with the strain rates of 10−4 s−1, 5 × 10−4 s−1 and 10−3 s−1 and at temperatures at 1060 °C, 1080 °C and 1100 °C. The superplastic deformation of the GH4151 alloy was reported here for the first time. The results reveal that the uniform fine-grained GH4151 alloy exhibited an excellent superplasticity and high strain rate sensitivity (exceeded 0.5) under all experimental conditions. It was found that the increase of strain rate resulted in an increased average activation energy for superplastic deformation. A maximum elongation of 760.4% was determined at a temperature of 1080 °C and strain rate of 10−3 s−1. The average activation energy under different conditions suggested that the superplastic deformation with 1 × 10−4 s−1 in this experiment is mainly deemed as the grain boundary sliding controlled by grain boundary diffusion. However, with a higher stain rate of 5 × 10−4 s−1 and 1 × 10−3 s−1, the superplastic deformation is considered to be grain boundary sliding controlled by lattice diffusion. Based on the systematically microstructural examination using optical microscope (OM), SEM, electron backscatter diffraction (EBSD) and TEM techniques, the failure and dynamic recrystallization (DRX) nucleation mechanisms were proposed. The dominant nucleation mechanism of dynamic recrystallization (DRX) is the bulging of original grain boundaries, which is the typical feature of discontinuous dynamic recrystallization (DDRX), and continuous dynamic recrystallization (CDRX) is merely an assistant mechanism of DRX. The main contributions of DRX on superplasticity elongation were derived from its grain refinement process.

Thermodynamic calculations of precipitation of TCP phase and carbide phase of Ni-Fe base superalloys for ultra-supercritical power plants

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超超临界电站用镍铁基高温合金TCP相和碳化物相析出的热力学计算

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Segregation and homogenization for a new nickel-based superalloy

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Element segregation and solidification behavior of a Nb, Ti, Al Co-strengthened superalloy ЭК151

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Investigation of solidification and high-temperature deformation behavior of Ni-base alloy ЭК151

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新型镍基高温合金ЭК151凝固偏析及高温变形行为研究

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Segregation behavior and investigation on homogenization for a new difficult-to-deform superalloy ЭК151 ingot

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新型难变形高温合金ЭК151的偏析行为及均匀化工艺研究

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Newton's law of cooling

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Effect of B and C on solidification segregation and hot ductility of U720Li alloy

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B和C对U720Li合金凝固偏析和热加工塑性的影响

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Research progress of precipitated phase in GH4720Li superalloy

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GH4720Li合金中析出相的研究进展

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Effect of heat treatment parameters on microstructure and hot workability of as-cast fine grain ingot of GH4720Li alloy

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GH4720Li was Ni-Cr-Co base precipitation strengthened superalloy and widely used for high performance applications such as disks and blades of either aircraft engines or land-based gas turbines attributing to its excellent properties including resistance to creep and fatigue, together with corrosion, fracture and microstructural stability for the intended applications. Compared with the double-melting process (vacuum induction melting (VIM)+electroslag remelting (ESR) or VIM+vacuum arc remelting (VAR), a triple-melting process (VIM+ESR+VAR) can eliminate the segregation coefficient of the alloying elements and reduce the content of impurity elements, while the ingot fabricated by the triple-melting process also exhibited lots of shortcomings, such as the coarse grains, dendritic structure, microstructure defects and high forging temperature. The as-cast fine grain ingot prepared by grain refining casting process can eliminate the microscopic shrinkage, reduce the differences among three crystalline regions and improve the hot workability as a result. However, it was hardly to avoid the microstructure defects by simply improving the casting process attributing to its large number of alloying elements. Therefore, the homogenization treatment was always performed on the superalloy ingot. In this work, the optimized homogenization parameter was identified according to the investigation on the microstructure evolution under various homogenization treatment conditions and hot workability of as-cast fine grain ingot after homogenization treatment. The relationships of one-stage as well as two-stage homogenization treatment parameters and segregation coefficient as well as volume fraction of eutectic phase were investigated indepth. The hot workability of the homogenized samples under various conditions was also analyzed with the help of hot compression tests. Experimental results revealed that the increased homogenization treatment temperature and extended holding time were able to decrease the volume fraction of eutectic phase and segregation coefficient of the alloying element significantly. Hot compression tests by the Gleeble 3800 dynamic thermal-mechanical testing machine indicated that the samples suffered two-stage homogenization treatment followed by the slowly cooling rate (1140 ℃, 12 h+1170 ℃, 10 h, 0.2 ℃/min furnace cooling to 1010 ℃, and then air cooling) exhibited better hot workability (the maximum reduction rate of 50% deformed at 1120 ℃, 1 s-1). Discontinuous dynamic recrystallization was identified as the mainly nucleation mechanism of the alloy, and the recrystallized grains preferred to nucleate at the boundaries of the original grains according to the microstructure observation of hot compressed samples. In additions, the M(C, N) type precipitates were able to promote the occurrence of dynamic recrystallization behavior. Homogenization treatment experiments and microstructure observation suggested that the optimized treatment parameters of the as-cast fine grain ingot was 1140 ℃, 12 h+1170 ℃, 10 h, 0.2 ℃/min furnace cooling to 1010 ℃, and then by air cooling.

热处理工艺对GH4720Li合金细晶铸锭组织与热加工性能的影响

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Effect of thermal processing on critical grain growth of extruded FGH4096 alloy

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热加工工艺对挤压态FGH4096合金临界晶粒长大的影响

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Study on microstructure and properties of shaped ring parts for super alloy GH4738

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The forming process of shaped ring part for super alloy GH4738 was numerically simulated by the finite element method, and the microstructure and properties of shaped ring part were characterized under two schemes of pre-rolling and final rolling at 1060℃ and pre-rolling and final rolling at 1080℃, respectively. The results show that the distribution of equivalent strain for the whole ring part varies along the axial gradient, but the uniformity of equivalent strain distribution is lower to make the ring form difficultly. However, the method of pre-rolling and final rolling at 1080℃ is more conducive to obtaining uniform microstructure, and the equivalent strain required to obtain uniform microstructure at this temperature is no more than 0.5. Furthermore, the tensile strength, plasticity and creep properties under two schemes are basically the same, and the yield strength at room temperature under 1080℃ is slightly lower, while the yield strength at high temperature is higher, and the stress rupture property is 1.8 times of that at 1060℃. Therefore, under the condition that the equivalent strain of rolling is no less than 0.5 and the scheme of pre-rolling and final rolling at 1080℃ is adopted, the shaped ring part of super alloy GH4738 is rolled, and the uniform microstructure is obtained to help to improve the stress rupture property of ring parts.

GH4738高温合金异形环件组织与性能研究

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Solidification and segregation behavior of nickel-based superalloy GH4282

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镍基高温合金GH4282的凝固和偏析行为

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Multimodal size distributions of γ′ precipitates during continuous cooling of UDIMET 720 Li

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A comparison of the precipitation behavior in PM γ-γ' nickel-base superalloys

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Dependence of creep performance and microstructure evolution on solution cooling rate in a polycrystalline superalloy

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Effects of heat treatment on the microstructure evolution and the high-temperature tensile properties of Haynes 282 superalloy

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Kinetics and mechanisms of γ' reprecipitation in a Ni-based superalloy

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The reprecipitation mechanisms and kinetics of gamma' particles during cooling from supersolvus and subsolvus temperatures were studied in AD730TM Ni-based superalloy using Differential Thermal Analysis (DTA). The evolution in the morphology and distribution of reprecipitated gamma' particles was investigated using Field Emission Gun Scanning Electron Microscopy (FEG-SEM). Depending on the cooling rate, gamma' particles showed multi or monomodal distribution. The irregularity growth characteristics observed at lower cooling rates were analyzed in the context of Mullins and Sekerka theory, and allowed the determination of a critical size of gamma' particles above which morphological instability appears. Precipitation kinetics parameters were determined using a non-isothermal JMA model and DTA data. The Avrami exponent was determined to be in the 1.5-2.3 range, suggesting spherical or irregular growth. A methodology was developed to take into account the temperature dependence of the rate coefficient k(T) in the non-isothermal JMA equation. In that regard, a function for k(T) was developed. Based on the results obtained, reprecipitation kinetics models for low and high cooling rates are proposed to quantify and predict the volume fraction of reprecipitated gamma' particles during the cooling process.

High-throughput fabrication of nickel-based alloys with different Nb contents via a dual-feed additive manufacturing system: Effect of Nb content on microstructural and mechanical properties

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The thermal stability of topologically close-packed phases in the single-crystal Ni-base superalloy ERBO/1

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Development of typical hard-to-deform nickel-base superalloy for turbine disk served above 800oC

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800℃以上服役涡轮盘用难变形镍基高温合金研究进展

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Morphological instability of spherical γ′ precipitates in a nickel base superalloy

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The dendritic growth of γ′ precipitates and grain boundary serration in a model nickel-base superalloy

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An approach toward understanding unstable gamma prime precipitate evolution and its effect on properties

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Microstructure and tensile properties optimization of MIM418 superalloy by heat treatment

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