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creep property research of new martensite heat-resistant steel G115

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Baosteel Technical Research 2024年第3期18卷 23-28页

作者： ZHAI Guoli Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201999China

G115 steel was jointly developed by China Iron & Steel Research Institute Group Co.,*** Baosteel for usage in 600-650 ℃ ultrasupercritical boiler *** a hot extruded G115 tube,creep tests were conducted under a constant stress of 130 MPa and temperatures of 625,650 and 675 ℃.Comparing creep curves under different temperatures,it is observed that the creep performance of a G115 tube is more sensitive to temperature than ***-state creep rates of creep specimens are significantly increased by enhancing the temperature.A micro-structural analysis of ruptured creep specimens under a stress of 130 MPa and temperatures of 650 ℃ and 675 ℃ was performed;the fracture mechanism of creep specimens under these two temperatures mainly included the appearance of creep holes on the grain boundary and a decrease in the martensite lath density.

关键词： G115 steel creep property steady-state creep rate

Effects of rejuvenation heat treatment on microstructure and creep property of a Ni-based single crystal superalloy

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Journal of Materials Science & Technology 2021年第1期60卷 206-215页

作者： K.J.Tan X.G.Wang J.J.Liang J.Meng Y.Z.Zhou X.F.Sun Superalloys Division Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Both surface and internal microstructures of a second-generation Ni-based single crystal(SX) superalloy were studied after creep and rejuvenation heat treatment(RHT).It is indicated that the microstructures,such as the dislocation network,the γ phase and the γ' phase,can be recovered to those after the standard heat treatment(SHT).It is found that RHT affected zone(RAZ) formed at the surface is composed of theγ'-free layer,the transition layer and the recrystallization(RX),which are less than 20 μm in depth *** depth of the RAZ doesn't affect the properties of the *** morphology of γ' phase at the RAZ is related to the composition of the *** average creep life after RHT is close to the average life after *** is concluded that RHT could effectively repair SX parts and increase the total life of the sample after a damage by creep.

关键词： Superalloys Rejuvenation heat treatment Microstructure creep property

Microstructural evolution and restoration of creep property for a damaged K403 alloy after rejuvenation heat treatments

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Rare Metals 2021年第7期40卷 1865-1871页

作者： Liang Wang Xiao-Guang Yang Hong-Yu Qi Duo-Qi Shi Shao-Lin Li School of Energy and Power Engineering Beihang UniversityBeijing 100191China Beijing Key Laboratory of Aero-Engine Structure and Strength Beijing 100191China

Rejuvenation heat treatments can restore the microstructures and mechanical properties of the degraded turbine blades in gas turbine *** we analyze the effects of rejuvenation heat treatments on the microstructural characteristics and mechanical properties of damaged and undamaged specimens of a Ni-based superalloy,*** damaged specimens were found to have degraded microstructures and shorter creep lifetime than the undamaged *** rejuvenation heat treatment proved beneficial,especially for specimens exposed to damage for 50 *** addition,the microstructure recovery and creep life were found to depend on the predamage durations of the specimens.A y’-precipitate-based creep lifetime model was established to predict the residual lifetime based on the microstructural information.

关键词： Microstructural evolution creep property Restoration Rejuvenation heat treatments

Microstructure and creep property of DZ125 Nickel-based Superalloy

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Microstructure and Creep Property of DZ125 Nickel-based Supe...

Improvement for creep strength of a second-generation single crystal superalloy by design of heat treatments

中国材料大会2012

作者： Sugui Tian Xianlin Meng Ning Tian Huichen Yu School of Materials Science and Engineering Shenyang University of Technology Beijing Institute of Aeronautical Materials

ISBN: (纸本)9783037856086

By means of creep property measurement and microstructure observation, an investigation has been made into the creep behaviors of DZ125 superalloy at high temperature and low stress. Results showed that the superalloy under the applied stress of 137MPa at 1293 K displayed a better creep resistance, and the apparent creep activation energy of the alloy during steady state creep was measured to be Q = 325.57 kJ/mol. The various microstructures were displayed in different regions of the sample, thereinto, the rafted γ’ phase was uniformly distributed in the regions far away from the fracture, but the twisted and coarser rafted γ’ phase appeared in the region near the fracture. The deformation mechanism of the alloy during steady state creep was the dislocations climbing over the rafted γ’ phase. In the later stage of creep, significant amount of dislocations shearing into the rafted γ’-phase promoted the initiation and propagation of the cracks along the boundaries up to the occurrence of fracture, which was though to the fracture mechanism of the alloy during creep.

关键词： DZ125 nickel-based superalloy Microstructure creep property

来源： cnki会议评论

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cnki会议

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Rare Metals 2024年第1期43卷 342-350页

作者： Wan-Shun Xia Xin-Bao Zhao Jia-Chen Xu Quan-Zhao Yue Qing-Qing Ding Huan-Chang Duan Yue-Feng Gu Hong-Bin Bei Ze Zhang Institute of Superalloys Science and Technology School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China State Key Laboratory of Silicon and Advanced Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China

Design of heat treatments is related to the key technology for development of nickel-based single crystal superalloys(Ni-SXs). Based on the full understanding of the solidification characteristics, this work applies optimization design of heat treatments for a second-generation Ni-SX. Microstructure evolution and creep properties are compared in the material under conventional/standard(Std.) and optimized(Opt.) treatments. For the Std. sample,strong dendritic segregations determine inconsistent microstructure evolution in the dendritic(D) and interdendritic region(ID), while the latter serves as weak area to have the prior microcrack initiation, damaging overall performance of the alloy. The Opt. treatment applies higher homogenization temperature, leading to overall reduced segregations, while not inducing incipient melting. A lower temperature of first-step ageing is used to lower the size ofγ'particles. These help to form the more uniform microstructure in dendritic and interdendritic region and relieve the inconsistent microstructure evolution. The balanced local strength makes ID no longer as the weak area,thus restricting microcrack initiation. Great improvement of high temperature and low stress property is obtained by this progress, leading to the pronounced increase of creep rupture life under 1100 °C/140 MPa.

关键词： Single crystal superalloy Heat treatment Segregation Solidification creep property

Effect of solution cooling rate on the microstructure and creep deformation mechanism of a rhenium-free second-generation single crystal superalloy

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Journal of Materials Science & Technology 2022年第36期131卷 14-29页

作者： Xipeng Tao Yunling Du Xinguang Wang Jie Meng Yizhou Zhou Jinguo Li Xiaofeng Sun Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

Various cooling scenarios(water,oil,air and furnace)were employed to study the impacts of the solution cooling rate(SCR)on the microstructure and creep behavior of a novel single-crystal(SX)*** results showed that the cubic degree and size of theγphases were inversely proportional to the *** creep life first increased and then dropped dramatically with a reduction in the *** creep life of the sample cooled with air cooling(AC)was the highest,up to 144.90 h at 800℃/750 MPa and160.15 h at 1100℃/137 *** creep at 800℃/750 MPa,the improved creep life of the AC sample was mainly attributed to the fine cubicγphases,which decreased the rate ofγ-phase coarsening and favoured plastic deformation by promoting the active movement of *** AC helped theγphases become rich in Al,Ti and Ta while depleted in Co and Cr,which enhanced its stacking fault energy,thus promoting the formation of dislocation ***,the largest negative lattice misfit caused by AC induced denserγ/γinterface dislocation networks at 1100℃/137 MPa,which efficiently reduced the minimum creep *** calculated average dislocation spacing results indicated that the smallest density of excess dislocations corresponded to the AC sample,proving its greatest creep ***,the size of the secondaryγphases first decreased and then increased sharply with decreasing SCR during creep at 1100℃/137 MPa,when fine secondaryγphases had a positive role in the blockage of dislocation movement in the ***,the comprehensive SCR effect was explored to provide more guidance in the design of Re-free SX superalloys.

关键词： Solution cooling rate Microstructure creep property Deformation mechanism Single crystal superalloy

Microstructure and mechanical properties of a new Ti2AlNbbased alloy after aging treatment

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Rare Metals 2018年第11期37卷 942-951页

作者： Yong-Sheng He Rui Hu Wen-Zhong Luo Tao He Yun-Jin Lai Yu-Jun Du Xiang-Hong Liu State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Western Superconducting Technologies Co Ltd Shaanxi Province Engineering Laboratory for Aerial MaterialXi'an 710018China

A new TiAlNb-based alloy with the composition of Ti-22Al-25Nb-1Mo-1V-1Zr-0.2Si(at%) was fabricated in the sequence of arc melting, forging, solid solution and aging. Present paper focuses on the effects of aging temperatures(700, 750, 800, 850 and 900 ℃) on microstructure, room-temperature tensile properties as well as tensile properties at 650 ℃ and creep properties at650 ℃/150 MPa. It is obvious that the aging treatment promotes the precipitation of O lathes from B2 *** aging temperature increasing, the content of O phase decreases and its size increases gradually, which leads to the decrease in tensile strengths both at room temperature and 650 ℃ and a little increase in ductility. For creep properties, the sample aged at 700 ℃ shows the best creep resistance due to its extremely high O phase content. Aging at 800 ℃ leads to the decrease in the content of O phase and softening of the alloy significantly. However, with aging temperature further increasing from 800 to 900 ℃,the precipitated O phase will be coarsened gradually, which strengthens the alloy again.

关键词： Ti_2AlNb alloy Aging Microstructure Tensile property creep property

High-temperature creep properties of uranium dioxide pellet

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Transactions of Nonferrous Metals Society of China 2010年第2期20卷 238-242页

作者：高家诚王良芬王勇吴曙芳 College of Materials Science and Engineering Chongqing University

High-temperature creep properties of sintered uranium dioxide pellets with two grain sizes （9.0 μm and 23.8μm） were studied. The results indicate that the creep rate becomes a little faster with the reduction of the uranium dioxide grain size at the same temperature and the same load. At the same temperature, the logarithmic value of the steady creep rate vs stress has linear relation, and with increasing load, the steady creep rate of the sintered uranium dioxide pellet increases. Under the same load, the steady creep rate of the sintered uranium dioxide pellet increases with increasing temperature; and the creep rates of sintered uranium dioxide pellet with the grain size of 9.0 μm and 23.8 μm under 10 MPa are almost the same. The creep process is controlled both by Nabarro--Herring creep and Hamper-Dorn creep for uranium dioxide pellet with grain size of 9.0 μm, while Hamper---Dora creep is the dominantmechanism for uranium dioxide with grain size of 23.8 μm.

关键词： uranium dioxide pellet grain size creep property creep mechanism

Microstructural evolution of Mg-14Gd-0.4Zr alloy during compressive creep

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Journal of Magnesium and Alloys 2023年第9期11卷 3161-3173页

作者： Hui Shi Yuanding Huang Lixiang Yang Chunquan Liu Hajo Dieringa Chong Lu Lv Xiao Regine Willumeit-Römer Norbert Hort Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Research and Development Center Shanghai Spaceflight Precision Machinery Research InstituteShanghai 201600China School of Mechanical Engineering Guizhou UniversityGuiyang 550025China Institute of Material and Process Design Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany The Instrument Analysis Center Shanghai Jiaotong UniversityShanghai 200240China Institute of Product Technology and Systems Leuphana University LüneburgUniversitätsallee 1Lüneburg D 21335Germany

The present work reports the creep behavior and microstructural evolution of the sand-cast Mg-14Gd-0.4Zr alloy(wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 ℃ were performed under various applied stresses(i.e., 60, 80 and100 MPa). Among them, the sand-cast Mg-14Gd-0.4Zr samples examined under 250 ℃/80 MPa for 39 and 95 h, respectively, were chosen to systemically analyze their creep mechanisms using high-angle annular dark field-scanning transmission electron microscopy(HAADF-STEM).The obtained results showed that the enhancement of creep resistance can be mainly attributed to the coherent β' and β'_F phases with an alternate distribution, effectively impeding the basal dislocations movement. However, with the creep time increasing, the fine β'+β'_F precipitate chains coarsened and transformed to semi-coherent β_1 phase and even to large incoherent β phase(surrounded by precipitate-free areas) in grain interiors. The precipitate-free zones(PFZs) at grain boundaries(GBs) were formed, and they could expand during creep deformation. Apart from the main cross-slip of basal and prismatic dislocations, type dislocations were activated and tended to distribute near the GBs. The aforementioned phenomena induced the stress concentrations, consequently leading to the increment of the creep strain.

关键词： Magnesium alloys creep property Microstructures Precipitate chains Dislocation