检索结果-南通市图书馆

Effects of simulated on-fire processing conditions on the microstructure and mechanical performance of Q345R steel

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2016年第1期23卷 49-56页

作者： Yi-chao Peng Hao-hao Xu mai-cang zhang Department of Materials Technology Zhejiang Energy Technology & Research Co.Ltd. Department of Materials Science and Engineering University of Science and Technology Beijing

A series of simulated on-fire processing experiments on Q345R steel plates was conducted, and the plates＇ Brinell hardness, ten- sile strength, and impact energy were tested. Microstructure morphologies were systematically analyzed using a scanning electron micro- scope with the aim of investigating the effect of the steel＇s microstructure on its performance. All examined performance parameters exhib- ited a substantial decrease in the cases of samples heat-treated at temperatures near 700℃. However, although the banded structure decreased with increasing treatment temperature and holding time, it had little effect on the performance decline in fact. Further analysis revealed that pearlite degeneration near 700℃, which was induced by the interaction of both subcritical annealing and conventional spherical annealing, was the primary reason for the degradation behavior. Consequently, some nonlinear mathematical models of different mechanical perform- ances were established to facilitate processing adjustments.

关键词： low alloy steels heat treatment mechanical properties microstructure nonlinear mathematical models

Luminescence of Nanosized Supramolecular Material of Mesoporous Molecular Sieve and Samarium (Ⅲ) Complex

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2003年第4期19卷 504-507页

作者： YIN Wei zhang mai-sheng School of Chemistry and Chemical Engineering Sun Yat-sen(Zhongshan)UniversityGuangzhou 510275P.R.China

The solutions of rare earth complexes Sm(Phen) 2(TTA)(Bipy)(NO 3) 3 and Sm(L) x (TTA) 4-x (NO 3) 3 [L=Phen (1,10-phenanthroline) or Bipy(2,2′-bipyridine), x =4, 3, 2, 1, 0; TTA is 2-thenoyltrifluoacetone] in EtOH(1×10 -3 mol/L) were prepared. The coefficients of antenna effect are 31 5, 18 2 and 5 6 for Phen, Bipy and TTA, respectively, when the electron configuration of the excited state of the samarium atom in the complexes is 4 D 1/2 . The fluorescent intensity and the lifetime of the supramolecular encapsulation products of (CH 3) 3Si-MCM-41 and Sm 3+ complexes are stronger and longer than those of the encapsulation products of MCM-41 and Sm 3+ complexes respectively. The results show that the host with lipophilic channels is more favourable to the fluorescence of the rare earth complexes than the hydrophilic mesoporous molecular sieve. The fluorescent intensity of (CH 3) 3Si-MCM-41-Sm(Phen) 3(TTA)(NO 3) 3 is the strongest \{among\} the encapsulation series of Sm 3+ complexes, which is assumed to result from the greatly reduction of SiO-H vibration relaxation in host (CH 3) 3Si-MCM-41 and the presence of the discrete strong luminescent centres of the guest molecules associated with the nanosized material′s structure. The luminescent decay halftime of the supramolecular materials is much shorter than that of the powder of the samarium complexes. The result shows that the ligand transferring energy from the triplet state to the singlet state of Sm 3+ ( T 1→S , intersystem crossing) becomes higher. The fluorescent experimental results indicate that the interaction between the host and the guest influences the luminescent properties of the nanostructured supramolecular materials.

关键词： MCM-41(CH _(3)) _(3)Si-MCM-41 Supramolecular system Luminescence Exponential decay

Low-Cycle Fatigue and Creep-Fatigue Behaviors of a Second-Generation Nickel-Based Single-Crystal Superalloy at 760℃

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第10期33卷 1423-1432页

作者： Jian zhang Yuan-Yuan Guo mai zhang Zhen-Yu Yang Yu-Shi Luo Beijing Institute of Aeronautical Materials Beijing 100095China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

Low-cycle fatigue(LCF)behaviors of a second-generation nickel-based single-crystal superalloys with[001]orientation at 760℃ have been *** strain amplitudes were introduced to investigate the creep-fatigue *** LCF life of none tensile holding(NTH)was higher than that of the 60-s tensile hold(TH)at any strain *** the strain amplitude was 0.7%,the stacking and cross-slip dislocations appeared together at the γ/γ’coherent microstructure in both TH and NTH *** the strain amplitude of 0.9%,plenty of the cross-slip dislocations appeared inγchannel and other dislocations were stacking at γ/γ’***,the SFs still appeared in γ’phase with 60-s TH which caused cyclic *** the strain amplitude increased up to 1.2%,the dislocations are piling up at the γ/γ’interfaces and cutting through the γ’phase in both TH and NTH tests,which caused cyclic *** influences of strain amplitude and holding time were *** stress response behaviors occurred in different loading *** surface characteristic and fracture mechanism were observed by scanning electron *** result is helpful for building the relationship of various blade fatigue failure modes,cyclic stress response and microstructure deformation under different strain amplitudes.

关键词： Low-cycle fatigue Cyclic stress response behavior Dislocation morphologies

A new insight into rapid oxidation of alloy 925 contaminated by oxide powder

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第7期40卷 1872-1880页

作者： He Jiang Jian-Xin Dong mai-Cang zhang Jiang-Yang Li Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

Rapid oxidation takes place both in the laboratory and in industrial conditions when alloy 925 is contaminated by oxide powder,and the oxidation rate is much higher than ***,the rapid oxidation behavior and mechanism of alloy 925 were investigated by a series of comparison tests at 1160℃.It is found that the oxide powder produced during the oxidation process is mainly composed of NiCr_(2)O_(4)spinel,accompanied by NiO and NiMoO_(4).The oxide powder plays a triggering role in the rapid oxidation of alloy 925,as NiO has a strong affinity with O.A composition adjustment experiment of alloy 925 shows that rapid oxidation is the synergetic effect of Mo and Cu in the *** and Cu easily combine to form low melting point *** formation and volatilization of MoO_(3)oxide can destroy the completeness of the protective oxide *** MoO_(3)flux can dissolve protective Cr_(2)O_(3)and prevent the repair of the oxide layer and also promote the formation of nonprotective and easy-spall NiCr_(2)O_(4)*** synergetic effect of Cu and Mo in accelerating oxidation should be considered in any nickel-based alloy with a high content of Cu and Mo.

关键词： Rapid oxidation Synergetic effect Nickelbased superalloy

Effect of trace boron on microstructural evolution and high temperature creep performance in Re-contianing single crystal superalloys

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2020年第3期30卷 371-381页

作者： Yunsong Zhao Jian zhang Fuyang Song mai zhang Yushi Luo Hao Zhao Dingzhong Tang Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials School of Materials Science and Engineering Beihang University School of Material Science and Engineering University of Science and Technology Beijing China Electronic Product Reliability and Environmental Testing Research Institute

The effect of trace B on the microstructure and creep properties under 1100 °C/130 MPa in three single crystal superalloys with various levels of B(0, 0.01 and 0.02 wt %) additions was investigated. Compared with the boron-free alloy, the creep rupture life decreased slightly for the alloy with 0.01 wt % B, but dropped obviously for the 0.02 wt% B contained alloy. The low B addition had a slight effect on the main element compositions ofγ/γ′ by the high precision atom probe tomography(APT) analysis and no significant change of γ/γ′ misfit was observed. However, the contents of Re, Mo, Cr in γ phase were decreased with the high B addition, resulting in the decrease of γ/γ′ misfit and increase of the spacing of γ/γ′ interfacial dislocation networks. Meanwhile, the residual(γ+γ′) eutectics and borides with a large volume fraction obviously decreased the creep rupture properties in the high B addition alloy. This study is helpful for understanding the boron’s role of strengthening mechanism in high temperature creep of Ni-base single crystal superalloys.

关键词： Superalloys Boron γ/γ′ misfit Borides Creep properties

Hot corrosion behavior and mechanism of FGH96 P/M superalloy in molten NaCl–Na_2SO_4 salts

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2019年第2期38卷 173-180页

作者： He Jiang Jian-Xin Dong mai-Cang zhang Lei Zheng Zhi-Hao Yao Materials Science and Engineering University of Science and Technology Beijing

Hot corrosion behavior of FGH96 powder metallurgy(P/M) superalloy in 25 % NaCl + 75 % Na_2SO_4 molten salts at 650, 700, and 750 ℃ was investigated in this paper. The methods of mass loss measurement, X-ray diffraction(XRD), scanning electron microscopy(SEM),and energy-dispersive spectroscopy(EDS) were used *** experimental results show that hot corrosion kinetics follows a square power law at 650 ℃, while a linear one at 700 and 750 ℃. The corrosion layer is detected to be composed of Cr_2O_3, NiO, and Ni2S_3 at each *** cross-sectional morphologies and corresponding elemental maps indicate that the corrosion layer is a stratified structure of oxide and sulfide. The results and analyses confirm that the hot corrosion mechanism of FGH96 P/M superalloy is a cooperate process of oxidation and sulfidation. Furthermore, the relatively higher concentrations of Cr, Co, and Ti provide better corrosion resistance to the attack of S and Cl^-.

关键词： Nickel-based superalloy FGH96 Hot corrosion Molten salts

Relationship Between Grain Boundary Segregation of Antimony and Temper Embrittlement in Titanium-Doped Nickel-Chromium Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2011年第1期18卷 68-72页

作者： ZHENG Lei zhang mai cang DONG Jian-xin MENG Ye School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083China

The antimony segregation at grain boundary was observed and the temper embrittlement in titanium-doped nickel-chromium steel was analyzed. It is concluded that the antimony segregation at grain boundary is nonequilibium and the kinetics of temper embrittlement agrees well with those of nonequilibrium antimony segregation at grain boundary. Besides, the mechanism of nonequilibrium antimony segregation at grain boundary proved to be the most satisfactory one among the existing mechanisms to interpret the antimony induced embrittlement kinetics in the nick- el-chromiunl steel. Based on these, the activation energy and frequency factor of diffusion of antimony vacancy complexes were obtained according to the concept of critical time in nonequilibrium grain boundary segregation theory.

关键词： grain boundary segregation temper embrittlement critical time diffusion activation energy

Effect of the withdrawal rate on the microstructure and thermal durability of a third-generation single crystal superalloy

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2021年第3期31卷 493-500页

作者： Yunsong Zhao mai zhang Luyan Yang Yuanyuan Guo Jian zhang Hui Lu Yanhui Chen Dingzhong Tang Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials Institute of Microstructure and Property of Advanced Materials Beijing University of Technology

Single crystal Ni-based superalloys are the typical structural materials for high-pressure turbine blades,and their microstructure is critical in determining their mechanical *** withdrawal rate is a key parameter affecting the microstructure during the single crystal growth *** the present work the effect of the withdrawal rate on the microstructure of a third-generation single crystal superalloy containing 6.8 wt% Re has been investigated,and the creep resistance of the alloy *** results showed that increased withdrawal rate refined the dendritic structure,reduced dendritic arm spacing,promoted the growth of secondary tertiary dendrites and decreased solidification segregation with a reduced size of γ’ *** porosity density of the ascast alloy first decreased and then increased with the withdrawal rate,while the minimum porosity densityoccurred when the alloy was under the solidification condition of withdrawal rate of 4.5 mm/*** maximum creep rupture life of 326.4 h of the heat-treated alloys under the test condition of 1100℃/140 MPa also appeared at the alloys under the withdrawal rates of 4.5 mm/*** is believed that the minimum porosity density and reduced size of the γ’ phase may be the main reasons for the enhanced creep rupture life of the alloys with withdrawal rates of 4.5 mm/*** investigation provides theoretical support and a practical basis for the development of third-generation single crystal superalloys.

关键词： Nickel-based superalloy Withdrawal rate Microstructure Thermal durability

Mechanism of α-Cr precipitation and crystallographic relationships between α-Cr and δ phases in Inconel 718 alloy after long-time thermal exposure

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 312-317页

作者： Zhong-nan Bi Jian-xin Dong mai-cang zhang Lei Zheng Xi-shan Xie School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

To study the precipitation mechanism of α-Cr phase in Inconel 718 alloy, the samples after long-time aging at 650 and 677℃ were examined by microstructural observations and chemical phase analysis methods. Combining the thermodynamics and kinetics calculation results, α-Cr always precipitates in the vicinity of δ phase, because δ phase rejects Cr into the γ-matrix when growing. The selected area diffraction patterns confirm that the crystallographic relationships of α-Cr with 6 phase are （010）d/（1- 10）*** and [100]d/If 11 ]α-Cr- A graphic model is also presented to show the crystallographic relation between α-Cr and δ phases.

关键词： Inconel 718 precipitation mechanism crystallography thermodynamics kinetics