K416B Ni-based superalloy with high W content has good high temperature properties and low cost,which has a great development potential.To investigate the room temperature tensile property and the deformation feature ...K416B Ni-based superalloy with high W content has good high temperature properties and low cost,which has a great development potential.To investigate the room temperature tensile property and the deformation feature of K416B superalloy,tensile testing at room temperature was carried out,and optical microscopy (OM),scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the deformation and damage mechanisms.Results show that the main room temperature tensile deformation features of the K416B nickel-based superalloy are dislocations slipping in the matrix and shearing into γ’ phase.The <110> super-dislocations shearing into γ’ phase can form the anti-phase boundary two coupled (a/2)<110> partial-dislocations or decompose into the configuration of two (a/3)<112> partial dislocations plus stacking fault.In the later stage of tensile testing,the slip-lines with different orientations are activated in the grain,causing the stress concentration in the regions of block carbide or the porosity,and cracks initiate and propagate along these regions.展开更多
The effect of long-term thermal exposure on the tensile behavior of a high W content nickel-based superalloy K416B was investigated.The microstructure and the deformation characteristics were observed by scanning elec...The effect of long-term thermal exposure on the tensile behavior of a high W content nickel-based superalloy K416B was investigated.The microstructure and the deformation characteristics were observed by scanning electron microscopy and transmission electron microscopy,and the phase transformation of the alloy during long-term thermal exposure was analyzed by X-ray diffraction patterns and differential thermal analysis.Results showed that after thermal exposure at 1000℃,the MC carbides in the K416 B alloy decomposed into M_(6)C.During tensile deformation,dislocations slipping inγmatrix crossed over the M_(6)C by Orowan bowing mechanism.With the increase of thermal exposure time,the secondary M_(6)C reduced greatly the yield strength of the alloy at room temperature.Meanwhile,the continuous distribution of the secondary M_(6)C with great brittleness in the grain boundary could become the main source of crack,which might change the fracture characteristic of the alloy from trans-granular to intergranular.展开更多
The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results sho...The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.展开更多
基金financially supported by the National Basic Research Program of China(Nos.2010CB631200 and 2010CB631206)the National Natural Science Foundation of China(No.51701212,No.50931004,No.51571196,No.51601192 and No.51671188)+4 种基金the State Key Laboratory of Solidification Processing in NWPU(SKLSP201747)Liaoning Provincial Natural Science Foundation of China(No.2019-MS-336)the Key Regional Project of Science and Technology Service Network Program,Chinese Academy of Sciences(No.KFJ-STS-QYZX-079)the Youth Innovation Promotion Association Project,Chinese Academy of Sciences(2020)the National Science and Technology Major Project(J2019-VI-0018-0133)。
文摘K416B Ni-based superalloy with high W content has good high temperature properties and low cost,which has a great development potential.To investigate the room temperature tensile property and the deformation feature of K416B superalloy,tensile testing at room temperature was carried out,and optical microscopy (OM),scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the deformation and damage mechanisms.Results show that the main room temperature tensile deformation features of the K416B nickel-based superalloy are dislocations slipping in the matrix and shearing into γ’ phase.The <110> super-dislocations shearing into γ’ phase can form the anti-phase boundary two coupled (a/2)<110> partial-dislocations or decompose into the configuration of two (a/3)<112> partial dislocations plus stacking fault.In the later stage of tensile testing,the slip-lines with different orientations are activated in the grain,causing the stress concentration in the regions of block carbide or the porosity,and cracks initiate and propagate along these regions.
基金financially supported by the National Basic Research Program of China(Nos.2010CB631200 and 2010CB631206)the National Natural Science Foundation of China(Nos.51701212,50931004,51571196,51601192 and 51671188)+1 种基金the State Key Laboratory of Solidification Processing in NWPU(SKLSP201747)the Liaoning Provincial Natural Science Foundation of China(No.2019-MS-336)。
文摘The effect of long-term thermal exposure on the tensile behavior of a high W content nickel-based superalloy K416B was investigated.The microstructure and the deformation characteristics were observed by scanning electron microscopy and transmission electron microscopy,and the phase transformation of the alloy during long-term thermal exposure was analyzed by X-ray diffraction patterns and differential thermal analysis.Results showed that after thermal exposure at 1000℃,the MC carbides in the K416 B alloy decomposed into M_(6)C.During tensile deformation,dislocations slipping inγmatrix crossed over the M_(6)C by Orowan bowing mechanism.With the increase of thermal exposure time,the secondary M_(6)C reduced greatly the yield strength of the alloy at room temperature.Meanwhile,the continuous distribution of the secondary M_(6)C with great brittleness in the grain boundary could become the main source of crack,which might change the fracture characteristic of the alloy from trans-granular to intergranular.
基金supported financially by the National Natural Science Foundation of China (Nos. 11332010,51671189 and 51701210)the Project from China Huaneng Group Co. Ltd. (No. ZD-15-HJK02)
文摘The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.