bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure of Nb-Ta-V Based Hydrogen Permeation High Entropy Alloys
Authors: Wang Nai Juan , Liu Yuan
Published: March 2016

High-entropy alloys of NbTaVTiNi, NbTaVTiCo, NbTaVHfCo, NbTaVHfNi, and NbTaVZrNi were synthesized by vacuum arc melting. The crystal structure was identified by an X-ray diffractometer analysis. Microstructures and element composition of the resulting alloys were investigated using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer. All alloys presented the dendritic structure which is mainly composed of body-centered cubic (NbTaV,X) (X=Ti, Hf, Zr) phases and eutectic-like phases such as TiNi, TiCo, HfCo, HfNi and ZrNi. (NbTaV,X) phases take the function of hydrogen permeability while eutectic-like phases bear the responsibility of resistance to hydrogen embrittlement. Taking the microstructure of alloys into account, NbTaV-based high entropy alloys is appropriate for improving hydrogen permeability.
Influence of Cooling Rate on Phase Transformation of a α+β Titanium Alloy
Authors: Fei Yue , Wang Xin Nan , Shang Guo Qiang , Li Jing , Zhu Li Wei , Zhu Zhi Shou
Published: March 2016

Effect rules of cooling rate on phase transformation and microstructure of a α+β titanium alloy were studied by thermal dilatometer method. Specimens under different cooling rates from 0.05°C/s to 2.5°C/s were analyzed by using X-ray diffraction (XRD), optical micrograph (OM) and Vickers micro-hardness. The results showed that the starting temperature of β to α phase transformation gradually decreased with the increase of cooling rate. The finishing temperature of β to α phase transformation firstly decreased and then increased with the increase of cooling rate. The typical lamellar structures were observed under the cooling rates from 0.05°C/s to 0.2°C/s. The layer thickness of α phase became thinner and the precipitation content of α phase reduced under the cooling rate of 0.5°C/s. The α phase was fine acicular and the precipitation content of α phase reduced obviously under the cooling rate of 2.5°C. The effect rule of cooling rate on micro-hardness was that the value of micro-hardness firstly decreased and then increased with the cooling rate increasing.
Influence of Electric Pulse Heat Treatment on the Dynamic Mechanical Behavior of TC6 Titanium Alloy
Authors: Pei Chuan Hu , Li Zhen Xi , Fan Qun Bo , Ding Jian Shan
Published: March 2016

In order to improve the dynamic mechanical properties of TC6 titanium alloy, the effect of electric pulse heat treatment on the dynamic properties and microstructures of TC6 has been investigated in this paper. It was observed that the secondary α phase was successfully controlled through rapid temperature rising and proper temperature holding by the electric pulse. Compared with traditional heat treatment methods, the electric pulse treatment can obviously refine the grains of secondary α phase. In addition, the refined second α phase distributed uniformly with fine equiaxed and lamellar shapes. As a result, this refined second α phase will resist the expansion of cracks and promote the coordination deformation of grains. According to the dynamic compression test results, it can be found that the adiabatic shear susceptibility of the microstructure obtained from the electric pulse treatment obviously decreased. On the other hand, the dynamic ductility and absorbed energy were much higher than that of the microstructure (equiaxed, bi-modal and basket weave structures) obtained from traditional heat treatments.
Study on Rotating Bending Fatigue Property of Ti65 Titanium Alloy
Authors: Wang Xu , Li Si Qing , Liu Jing Nan
Published: March 2016

The rotating bending fatigue properties of Ti65 titanium alloy blisk forging was studied in the present investigation. The smooth and notched specimens were prepared to test the fatigue properties at room temperature and 650°C. Meanwhile, the influences on rotating bending fatigue of temperature and type were analyzed. Furthermore, the fractural morphology was observed through scanning electron microscopy. The results showed that the medium fatigue strength of Ti65 titanium alloy decreased at 650°C compared with that at room temperature, and the fatigue strength of notched specimens indicated the same significant declination at different temperatures compared with smooth specimens. At room temperature the medium fatigue strength of smooth and notched are 473MPa and 173MPa, respectively, and the fatigue notch sensitive coefficient was 0.87. At 650°C the medium fatigue strength of smooth and notched specimens are 427MPa and 168MPa, where the fatigue notch sensitive coefficient was 0.78.
Microstructure Evolution and Hardness of AlCrFeNixMo0.2 High Entropy Alloy
Authors: Dong Yong , Qiao Dong Xu , Zhang Huan Zhi , Lu Yi Ping , Wang Tong Min , Li Ting Ju
Published: March 2016

The microstructures, phase composition and hardness of the AlCrFeNixMo0.2 high entropy alloy (x=0.5, 0.8, 1.2 and 1.5, the x values refer to molar ratio) were reported. When the value of x was smaller than 1.2, the alloys consisted of BCC and B2 structures. The BCC and B2 phases were identified to be (Cr, αFe) solid solution and NiAl intermetallic compound, respectively. With the increase of x from 0.5 to 1.2, the microstructure transformed from dendrite/inter-dendrite to eutectic microstructures. When the x was equal to 1.5, besides BCC and B2 phases, another CrFe2.32MoNi phases formed and Net-like (Cr, αFe) phases distributed in the NiAl intermetallic compound matrix. The hardness first decreased then increased with the increase of Ni content. Generally, Ni element is a FCC stabilizer. However, in AlCrFeNixMo0.2 alloys, Ni element promoted the formation of B2 and CrFe2.32MoNi phases. The influence mechanism of Ni element was discussed systematically.
Microstructural Difference between Unreinforced Canning of TC17 Alloy and the Matrix in SiCf/TC17 Composite Fabricated by HIP Process
Authors: Wang Min Juan , Huang Hao , Li Si Qing , Li Hu , Xie Chuan , Huang Xu
Published: March 2016

Continuous unidirectional SiCf/TC17 composite has been fabricated by hot isostatic pressing (HIP). After consolidation, the TC17 canning (the unreinforced ambient portion of the specimen) showed an equiaxed microstructure, whereas the matrix of SiCf/TC17 composite (deposited on the continuous SiC fibers by magnetron sputtering) exhibited a typical lamellar structure. In this work, the heat treatments under different condition, XRD, SEM and WDS have been employed to characterize and analyze the microstructural difference. The results indicated that the difference in β transus temperature (Tβ) between the canning and matrix of TC17 alloy induced the microstructural diversity. The introduction of C element (an intensive α stabilizing element) into the matrix alloy may be ascribed to the diffusion of carbon layer at the surface of SiC fiber. As a result, Tβ of matrix TC17 alloy increased to above 1000 °C, much higher than that of the canning TC17 alloy (890 °C). The investigation of microstructure difference reveals the microstructure evolution in SiCf/TC17 composite, which can provide an effective reference for following processing design.
Enhanced Tensile Properties of Graphene-Al5083 Composite Prepared by Hot Pressing and Hot Extrusion
Authors: Zhang Hai Ping , Xiao Wen Long , Ameyama Kei , Ji Guo Fu , Yang Ming Juan , Ma Chao Li
Published: March 2016

Graphene, with outstanding mechanical properties of 1TPa of Young’s modulus and 130GPa of tensile strength, has been considered as an excellent reinforcement in composites. Graphene nanoplates (GNP) reinforced Al5083 alloy composites were successfully fabricated by powder metallurgy method. Flake-like Al5083 powder was firstly added into a GNP-alcohol solution and then dried in vacuum oven at 343 K for 5 h. The composite powders were sintered at 723K under pressure of 300 MPa for 1 h, followed by extrusion at 623 K. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed for microstructure characterization. Al4C3 cannot be observed in the composite, suggesting that there was no reaction occurred between GNP and Al matrix during the processing. Tensile test results revealed that the ultimate tensile strength and tensile elongation of 0.3wt.%GNP/Al5083 composites were 580MPa and 15%, respectively, showing optimal combination of strength and ductility. The relevant strengthening mechanisms of the composites were discussed.
Research on Effect of Alloy Elements on Equilibrium and Properties of Ni-Cr-Co Type Nickel-Based Superalloy
Authors: Zhang Qing Quan , Li Ming Yang , Wei Ran , Wu Hui Yun , Li Zhen Rui
Published: March 2016

Ni-Cr-Co type Nickel-based super alloy Inconel 740H was studied. The effect of Nb, Al and Ti on the equilibrium of this alloy was analyzed by JMatPro software. The amount of Ti and Nb should be controlled by 1.50wt.%, and meanwhile, Al should be 1.0-2.0wt.%. If Mo and W were added the amount of Mo should be in the range of 1.0-2.0wt. %, and W should be about 1.0wt.%. Based on these results, three types of new alloys were designed, which contain Ni-Cr-Co-Mo type (1#), Ni-Cr-Co-W type (2#) and Ni-Cr-Co-Mo-W type (3#). Compared with the Ni-Cr-Co type Inconel 740H alloy, the room temperature strength, high temperature strength and high temperature durable performance of the three new alloys improved, which can provide the evidence and reference to optimize the chemical composition of Inconel 740H alloy, i.e., adding 1.50wt.% Mo and 1.0wt.% W individually or together.
Decreasing Defects of Center Porosity and Improving Secondary Pipe Castings for Superalloy Ingots by Dynamics Methods
Authors: Wang Chao , Li Zhen Rui , Niu Yong Ji , Shi Shi Feng , An Ning
Published: March 2016

The causes and the influence factors of the defects of center porosity and secondary pipe of the casting superalloy ingot are briefly introduced, and the study on the principle and technical characters of grain refinement technology with dynamic methods carried out. The mechanism, working parameter and the test result of the typical application methods including the technologies of vibration of ultrasonic, the vibration of mould, the stir of mould and oscillation in the riser were investigated in detail. By comparing the advantages and disadvantages of different methods and also according to the practical production situation of our company, the most appropriate one for improving the defects of center porosity and secondary pipe is proposed.
Effect of Sulfur on the Hot Plasticity of GH625 Superalloy
Authors: Wu Hui Yun , Fu Zu Ming , Zhang Qing Quan , Li Ming Yang , Wei Ran , Cao Yu , Li Zhen Rui
Published: March 2016

The influences of sulfur on the hot plasticity of superalloy GH625 were studied. The results indicate that the area reduction rate were 70% between 950°C to 1250°C with the S content below 0.0020%. When the S content is higher than 0.0025%, the area reduction rate was below 50%. The fractography was examined and analyzed by scanning electric microscope (SEM). The SEM results showed that the tensile fracture was cleavage fracture with the S content above 0.0030%. There were dimples in the tensile fracture when the S content was 0.0020% and below. It is indicated that the content of sulfur has great effect on the mechanical properties of GH625. In order to improve the hot plasticity of superalloy GH625, the content of sulfur should be controlled below 20ppm.
Effect of Al on the Microstructure and Mechanical Properties of HK40 Heat-Resistant Steel at High Temperature
Authors: Zhang Yan , Mei Yu Fei , Zhou Ning , Liu Zheng Qin , Sun Yu Fu
Published: March 2016

The high-temperature mechanical properties and microstructure of HK40 heat-resistant steel with different content of Al were investigated. The results from scanning electron microscope and transmission electron microscope showed that a large amount of spheroidal and dispersed γ′ phase were observed HK40 steel with 4.72wt.% and 7.10wt.% Al. The diameter of γ′ phase decreases from about 1.5μm to 50nm after solution treatment of 1200°C for 5h. The results of short term tensile test showed that tensile strength at 900°C decreased and the elongation was improved with increasing Al content. The oxides in the alloy with 4.72wt.% and 7.10wt.% Al were more uniform and finer than that in the alloy with and without 1.68wt.% Al.
Role of Cobalt in the Microstructural Stability of Single Crystal Superalloys
Authors: Chen Jing Yang , Li Qing , Li Jie , Tang Xin , Xiao Cheng Bo
Published: March 2016

The effects of Co additions on the evolution of γ' precipitates and topologically close-packed (TCP) phases during thermal exposure at 950 °C were investigated for two Ni-based single crystal superalloys with 7.9 wt.% Co and 9.1 wt.% Co. The results indicated that the γ′ morphology was not affected by Co content, whereas γ′ volume fraction decreased and precipitate size increased due to lower Co addition after standard heat treatment. The coarsening of γ′ precipitates in both alloys was controlled by diffusion. The γ′ coarsening rate increased, while the stability of γ′ volume fraction decreased due to lower level of Co addition during 950 °C thermal exposure because more Co addition suppressed the diffusion process. High Co addition promoted the formation of μ phase after thermal exposure at 950 °C for 1000 h due to higher γ′ volume fraction, more stable γ′ volume fraction and higher electron vacancy number. The experimental results of μ phase precipitation showed good agreement with thermodynamic calculation by JMatPro.
Microstructure of Chemical Vapor Transport Deposition Single Crystal Tungsten Coating Working at 1600°C
Authors: Huang Hong Tao , Wei Yong Feng , Zheng Jian Ping , Tan Cheng Wen
Published: March 2016

Thermionic energy conversion is a process by which thermal energy is transformed into electrical energy directly without the intermediate steps. Microstructure of Chemical Vapor Transport Deposited (CVTD) single crystal tungsten coating working at 1600°C for 1000 h was investigated using optical microscopy and electron backscatter diffraction (EBSD) technique. The experimental results showed that the etching morphology of single crystal tungsten coating was not clear compared to the etching morphology before working. The electro-etched surface of single crystal tungsten coating mainly consist of {110} crystal planes and {112} crystal planes before working at 1600°C. The surface of the single crystal tungsten coating mainly consists of near {110} crystal planes and near {112} crystal planes instead after working at 1600°C.
Structure and Properties of W-Ti Thin Films Deposited by Magnetron Sputtering
Authors: Sun Guo Qi , Yong Sun , Duan Yong Hua
Published: March 2016

W-Ti thin films with different Ti contents were prepared by dc magnetron sputtering on silicon substrates of p-type (100) orientation, and the pure W and pure Ti thin films with the same thick were also prepared for comparison. The microstructure and properties of W-Ti thin film were characterized by XRD, SEM, AFM, microhardness tester and four-point probe method. The results show that the thin films exhibited a polycrystalline structure in the form of columnar grains, and only b.c.c. W phase could be registered in the films, and with the increase of Ti content, the solid solution of W-Ti was found. Compared to pure W film, the microhardness of W-Ti films decreased with the increasing of Ti content, while the sheet resistance rises with the increasing of Ti content. The microhardness of W-Ti thin films was higher than pure Ti thin films, and the sheet resistance was lower than pure Ti thin films.
Effect of the Porosity on Thermal Stress within TBCs Using Finite Element Method
Authors: Zhou Hui Hui , Song Peng , Liao Hong Xing , Huang Tai Hong , Lu J.S. , Ji Qiang , Zang Jun Jie
Published: March 2016

Thermal barrier coatings (TBCs) with NiCoCrAlY bond-coats (BC) and ceramic top coats (TBC) were prepared on IN738 superalloy by plasma spraying technology. Effect of porosity on the maximum stress under thermal cycling conditions was carried out by using finite element software ANSYS. The results showed that maximum axial thermal tensile stress in TBCs decreases from 868MPa to 498MPa with the increase of bond-coats porosity near the TGO/BC interface, and the maximum axial thermal compressive stress decreases from 1060MPa to 711MPa. The stress distribution changes with increasing bond-coats porosity near the TGO/BC interface. The simulation results are in agreement with the experiments, exhibiting a clearly evidence that the porous TBCs have a longer lifetime.
Correlation between Electrical Resistivity and the Structural Evolution of Zr-Based Bulk Amorphous Alloys
Authors: Gu Jia Chang , Han Xiao Tao , Chen Qi
Published: March 2016

The electrical resistivity of three kinds of Zr-based bulk amorphous alloys as a function of continuous increasing temperature was measured by the direct current four-probe method. Combining with Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis, the correlation between the electrical resistivity and structural evolution of these amorphous alloys has been demonstrated. The experimental results showed that three amorphous alloys all had a small negative temperature coefficient of resistivity (TCR<-10-4 K-1) before crystallization. Little change of the electrical resistivity related with the glass transition process was observed, while the electrical resistivity decreased sharply once the crystallization occurred. The onset of crystallization determined by the electrical resistivity measurement was far lower than that by DSC. The different stages of crystallization behavior could be evidently identified by the change of the electrical resistivity.
Core Losses Separation of Amorphous Alloy Core
Authors: Li Shan Hong , Li Li Jun , Li De Ren , Lu Zhi Chao
Published: March 2016

In this paper, the core losses of Fe80Si9B11, Fe78Si9B13 amorphous alloy cores were separated to investigate the behaviors of hysteresis loss, eddy current loss and additional loss in high frequency range. The results showed that the losses of amorphous alloy core were mainly composed of hysteresis loss in low frequency. With the increase of frequency, eddy current loss increased drastically compared with the hysteresis loss, the eddy current loss was greater than the hysteresis loss when the frequency was higher than 5 kHz and 6 kHz for amorphous alloy with the composition of Fe78Si9B13 and Fe80Si9B11, respectively. The eddy current loss proportion in total loss increased with the increment of frequency.
Research on Laser Brazing Applying Al-Based Amorphous Ribbon
Authors: Song Jing Hui
Published: March 2016

The Al-based amorphous ribbons were prepared by the copper roller melt spinning method, and then the laser brazing was carried out between aluminum alloy and aluminum alloy. Subsequently, the Micro Vickers Hardness Tester, Metallographic Microscope, Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) were used to characterize the hardness, morphology, micro structure and composition distribution of the welded joints respectively, so as to analyze the structural characteristic, performance characteristic and binding effect of the matrix metal joints. The results indicate that the prepared Al-based amorphous ribbon is of amorphous structure, the soldering point between aluminum alloy and aluminum alloy is well-connected and the joint’s hardness is identical to that of the base metal. The connection between the metal sheets can be achieved by using Al-based amorphous ribbon as solder, which could provide concrete references for the development and application of amorphous brazing in various fields.
Analysis of Rheological Behavior on Transformation Induced Plasticity Steel
Authors: Sun Ji Quan , Teng Sheng Yang , Yin Yan Jun , Niu Chuang
Published: March 2016

The cupping tests under different rate demonstrated that there was a correlation between the plastic deformation and shaping time of transformation induced plasticity (TRIP) steel, illustrating that there was also the rheology in the process of plastic forming for solid metal materials. The creep experiments were carried out by Gleeble 3500 thermal simulated test machine, and Mises yield rule was used to verify the creep experiments satisfying the visco-plastic conditions when the load was greater than yield strength. The visco-plastic deformation rate of creep experiments was obtained based on Bingham model. The viscous correlation coefficient (γ) was deduced, reaching that the viscosity of TRIP steel shows deformation resistance in the process of plastic shaping. These results provide the theoretical basis for increasing the plate yield and controlling the forming rate.
Growth of Equiaxed Dendrite in Al-20wt.%Cu Alloy by Synchrotron X-Ray Radiography
Authors: Cao Fei , Yang Fen Fen , Zou Cun Lei , Kang Hui Jun , Fu Ya Nan , Wang Tong Min
Published: March 2016

Synchrotron X-ray radiography was used to in-situ study the growth of equiaxed dendrite during the solidification of Al-20 wt.% Cu alloy. Equiaxed dendrites with two different morphologies were formed in nearly isothermal conditions. The image processing was used to improve the image quality. The time evolution of the primary dendrite arm length and the corresponding growth rates were analyzed. The experimental results indicated that the solute interaction was the main factor to influence the equiaxed dendrites growth. Besides, the rotation and floating of the dendrites were also observed during the early growth phase.
Wear Resistance Research of Advanced High Strength Steels
Authors: Zhi Chao , Gong Yi Fei , Zhao Ai Min , He Jian Guo , Ding Ran
Published: March 2016

The wear performance and wear mechanism under two-body abrasion of five advanced high strength steels, i.e. Nanobainite (NB) steel, Tempered Martensitic (TM) steel, Dual Phase (DP) steel, Transformation Induced Plasticity (TRIP) Steel and Twining Induced Plasticity (TWIP) steel were studied. By using the scanning electron microscopy (SEM), we investigated the wearing surface. Phase transformation strengthening behavior was also be discussed by analyzing the surface and sub-surface after abrasion. The results showed that micro-cutting was the major role of wear mode in the condition of two-body abrasion. In the circumstance of two-body abrasion, hardness was an important factor, the property of wear resistance enhanced while the hardness increased except for TM steel. NB steel possessed the best wear resistance which was 1.71 times higher than that of TWIP steel. The retained austenite transformed into martensite which can improve the hardness so that it enhanced the wear resistance of NB steel.
Ultrafast Electron Cascades in X-Rays Detector
Authors: Zhang Jian , Yi Tao , Su Ming , Yang Wei Ming , Liu Shen Ye
Published: March 2016

A new detection method based on the ultrafast refractive index change of semiconductor was used for X-rays detection. Since temporal and spatial resolutions are important parameters of the ultrafast X-rays detector, the electron cascades in gallium arsenide and cadmium selenide were studied using Monte Carlo method. According to the calculations, the energy deposition time and scale are similar in gallium arsenide and cadmium selenide at low energy region, but different at high energy region. Electron cascades don’t have much impact on getting picosecond time resolution and high spatial resolution.
Welding Thermal Crack Sensitivity Simulation of 9%Ni Steel
Authors: You Zong Bin , Li Ye Zheng
Published: March 2016

In this paper, the application of 9% Ni steel in natural gas storage tanks and the welding thermal crack tendency of 9% Ni steel were studied. For the section shrinkage and breaking strength of tensile specimens at different temperature, the high temperature tensile test (600°C~1450°C) of 9%Ni steel was carried out by Gleeble 3500 thermal simulation machine. The nil-ductility transition temperature (NDT), nil-ductility stength temperature (NST) and ductility recovery temperature (DRT) of 9%Ni steel were identified. The result showed that the NDT for 9% Ni steel was 1400°C, the NST was 1430°C, the DRT is 1370°C, and the brittle temperature range (BTR) was 60°C. In this study, the welding hot crack of 9% Ni steel was a little sensitive.
The Establishment and Application of 316LN Stainless Steel Database for AP1000 Primary Coolant Pipes
Authors: Wang Sheng Long , Yang Bin , Zhang Ming Xian , Wu Huan Chun
Published: March 2016

Nuclear grade 316LN austenitic stainless steel (ASS) with an exceptional combination of mechanical properties and corrosion resistance was used to produce AP1000 primary coolant pipe. In order to evaluate the microstructure evolution of the pipe during its forging process, the material database of the 316LN ASS is established with high integrity and reliability. In this paper, the thermal physical parameters, flow stress-strain data and the recrystallization kinetic equations of the 316LN steel are coupled, and the material database is systematically established. Most important, the reliability of the database is verified by an experiment.
Structural, Phonon and Thermodynamic Properties of the Rocksalt Structure LiF from First Principles
Authors: Hou Hai Jun , Guan Hao , Zhang Shun Ru , Xie Lin Hua , Wang Lei
Published: March 2016

The structural, electronic, phonon and thermodynamic properties of rocksalt (RS) structure LiF are studied using a plane-wave pseudopotential method within the local density approximation (LDA). The values of lattice constants, elastic constants, and bulk modulus and its pressure derivatives are in well agreement with the available experimental data and other theoretical results. The LiF crystal exhibits a wide band gap of about 8.727 eV. The linear response method is applied to determine the phonon dispersion, phonon density of states and Born effective charge. The phonon frequencies at the Γ, X, L points are analyzed using group theory. We also calculate the thermodynamic functions such as free energy, enthalpy, entropy, specific heat using the phonon density of states. We compare the present calculation results satisfactorily to experimental and previous theoretical results.
Numerical Simulation of Directionally Solidified Industrial Gas Turbine Hollow Blades by Liquid Metal Cooling
Authors: Yan Xue Wei , Tang Ning , Liu Xiao Fu , Guo Xin Li , Shui Guo Yan , Xu Qing Yan , Liu Bai Cheng
Published: March 2016

As a new method, liquid-metal cooling (LMC) process is used in manufacturing industrial gas turbines (IGT) blades. Numerical simulation is an effective way to investigate the grain’s growth and morphology, and optimize the process. In this paper, mathematical models for heat dynamic radiation and convection boundary of LMC process is established to simulate the temperature fields. Cellular Automaton (CA) method and KGT growth model are used to describe the nucleation and growth. Simulation results and experimental results are compared. The mushy zone and microstructure evolution are studied in detail. This study indicates that simulation and experimental results agree very well with each other. The withdrawal rate has an important influence on the shape of mushy zone and growth rate of the grain directly. A concave mushy zone is formed and the grain tends to convergent under an excessive high of withdrawal rate. But, the mushy zone has a convex shape and the grain is divergent under a smaller withdrawal rate. A variation withdrawal rate (from 2mm/min to 9mm/min) is found to obtain smooth mushy zone, which improves the parallelism of grain and produces high quality IGT blades.
Erosion Behavior of Blooie Line in Gas Drilling
Authors: Lv Dong Li , Zhang Tao
Published: March 2016

In this paper, based on mass conservation, momentum conservation and turbulence k-ε model, the incompressible flow fluid dynamics model in sand discharging process is established. Computational Fluid Dynamics (CFD) technology is adopted to solve the flow field in the bend pipe and the erosion laws of the pipeline wall are predicted coupling material erosion model. Four erosion models of carbon steel material are adopted respectively to calculate the erosion laws and comparison is conducted. Further parametric study is carried out and different influence factors (such as pipeline structure, flow of fluid, et al.) to the erosion laws of the blooie line are discussed. The results indicate that the distribution characteristics of the erosion damage and the law of the erosion rate are changed with impact parameters in the bend pipe. There are obvious distribution differences of the erosion rate within a certain angle range obtained from different erosion models.
Thermodynamic Database of the Phase Diagrams in the Au-RE Binary Systems
Authors: Li Yu Heng , Xu Fei , Yang Peng Wu , Li Jia Lian , Zhou Lu Jiang , Wang Shu Liang , Lin Yuan Hua , Liu Xing Jun
Published: March 2016

The thermodynamic database has been developed for Au-RE binary systems. Based on the experimental data including thermodynamic properties and phase equilibrium, the thermodynamic assessments of phase diagrams in the Au-RE (RE: Nd, Dy, Yb, Gd, Tb, Sm, Lu) binary systems were carried out by using the CALPHAD (Calculation of Phase Diagrams) method. The Gibbs free energies of the solution phases were described by substitutional solution model, and all of the intermetallic compounds were described by sublattice models. The calculated phase diagrams are congruent with the available experimental data. Combined with the assessed Au-RE (RE: La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) binary systems, the thermodynamic database of Au-RE binary systems has been developed, and some significant information of thermodynamic properties and phase equilibrium could be calculated, which is important for the further development of Sn-Au-RE high-temperature lead-free solders.
A Setup Calculation Method of Application Platform for Process Сontrol System of Tandem Cold Rolling Mills
Authors: Chen Jin Shan , Li Chang Sheng
Published: March 2016

Setup calculation function of the process control system for tandem cold rolling mills not only determinates the dimension accuracy of finished strip materials directly, but also affects the control of surface quality of strip materials. In the present work, an attempt was made to develop a new setup calculation method for tandem cold rolling mills to maximize the throughput and improve the surface quality of strips. Based on the application platform for level-2 process control system, the modular design method was adopted, and then the setup calculation function was developed. And four functional modules consisting of preset preparation module (PPM), basic setup calculation module (BSCM), dynamic setup calculation module (DSCM), and adaptive calculation module (ACM) were developed. The preset data from PPM were used in equipment of level-1 process control system, and the purposes of BSCM was to achieve high quality of products, reduce off thickness deviation and achieve stable rolling at maximum possible rolling speed for raising productivity. In order to minimize off error of preset and actual data, DSCM was provided. Thanks to the design of ACM, accuracy of mathematical model can be effectively improved on line. Ultimately, the precise model on setup calculation method for cold tandem rolling of strip steels was established, and then it was put into practical production. Statistics analysis showed that the measured data was in excellent agreement with the model, and exactly, the relative deviations on rolling force and delivery thickness of strips were less than 3.67% and 0.42%, respectively. The new setup calculation method has high precision and good generalization capability.
Effect of Melt Holding in Mushy Zone on the Nitrogen Content of 201 Austenitic Stainless Steel
Authors: Huang Tong , Jin Qing Lin , Lu Ya
Published: March 2016

The melting of a 201 austenitic stainless steel was conducted in mushy zone for 0, 5, 10, 15 min under nitrogen atmosphere. The effect of the holding time on nitrogen content was investigated. The results showed that with the increase of holding time, the nitrogen content was significantly increased. It was found that the holding in mushy zone could avoid ferrite region during solidification, and facilitate the diffusion of nitrogen from liquid into austenite. Thermodynamic analysis demonstrates that the difference between the chemical potential of nitrogen in liquid and austenite provides the driving force for the nitrogen diffusion. It is concluded that melt holding in mushy zone is an effective way for increasing the nitrogen content in stainless steel, and thus provides a new method for the production of high nitrogen stainless steel.
Study of the Microstructure and Mechanical Properties of a Medium Manganese Quenching and Partitioning (Q&P) Steel
Authors: Li Xiao Gang , Zhao Ai Min , Zheng Hong Hong , Sun Shao Heng , Yin Hong Xiang
Published: March 2016

The microstructure and mechanical properties of a medium manganese quenching and partitioning (Q&P) steel for automobile were investigated by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and mechanical property test. The grain size and recovery degree were greatly affected by annealing temperature normally. The result shows that the medium manganese steel after quenching and partitioning (Q&P) heat treatment exhibited good mechanical properties. The maximum tensile strength and yield strength was 1280MPa and 1421MPa at 600°C, respectively. Additionally, the product of strength and plasticity could reached to 40472MPa×% at 640°C. Annealing temperature also had a great influence on the volume of retained austenite which increases linearly with the rise of annealing temperature as well.
Effects of Solution Temperature on Microstructure of 2A66 Al-Cu-Li Alloy
Authors: Wu Yue , Wang Xu Dong , Li Jiong Li , Feng Zhao Hui
Published: March 2016

The effect of solution temperature on the solid solubility, microstructure and mechanical properties of 2A66 Al-Cu-Li alloy was studied by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile test. The results show that with the solution temperature increasing from 480°C to 520°C,the amount of residual phases decreased and the solid solubility increased obviously, while the recrystallization hardly changed with the increasing of solution temperature. With the solution temperature increased to above 530°C, the amount of residual phases almost did not change. With the solution temperature increasing to above 540°C, the alloy was over-burnt obviously. Complete dissolution of the particles in the 2A66 Al-Cu-Li alloy was obtained after solution treatment at 520°C.
Effect of Flat Heat Pipe on the Properties of the FSW Joint
Authors: Lu Sheng , Zhang Wei , Chen Shu Jin , Yao Shou Guang
Published: March 2016

Friction stir welding (FSW) joint is characterized with asymmetric gradient in three dimensions. The purpose of this thesis is trying to find the effective methods to improve the microstructure and strength of AZ31 magnesium alloy joint of FSW. In order to achieve this aim, one heat pipes was designed and applied to the FSW process. Using different cooling methods, FSW experiments were carried out in air and under the conditions of heat pipes controlling. The welding temperature fields, macrostructure, microstructure and mechanical property of the joint were investigated. The result shows that with the heat pipes controlling, the maximum peak temperature decreased by 100 °C. The average duration of high temperature was 36s which shortens 11s compared to that in air. After applying the heat pipes the microstructure in the weld nugget zone were slightly finer than that in air. The average tensile strength of the welding joints was higher than that in air. The highest tensile strength reached 220.4 MPa, more than 90% of the base material strength; The fracture position located between thermal mechanical affected zone and heat affected zone. Under the condition of applying heat pipes, the number of dimple gradually increased and the tensile rupture pattern was ductile-brittle fracture.
Corrosion Behavior of Austenitic Stainless Steel in Hydrochloric Acid Solution and Flow
Authors: Liu Bing Yi , Xue Ya Jun , Yang Zong Hui , Fang Xin Xian
Published: March 2016

The corrosion behaviors of austenitic stainless steels, 304 and 316L as a contrast material, are investigated in hydrochloric acid corrosion under different conditions including immersion corrosion, single-phase flow and two-phase flow, respectively. The corrosion mass loss test and electrochemical test were carried out to evaluate the influence of medium temperature and concentration. The specimen surface morphologies and chemical compositions were obtained using scanning electron microscope to analyze the corrosion mechanism. The results show that the static corrosion rates of 304 and 316L steels and erosion corrosion rates of 304 steel increase obviously with the medium temperature increasing, but, the effect of hydrochloric acid concentration on their corrosion rate is less than that of the temperature. The corrosion current density values of 304 stainless steel increase and its passivation region of the polarization curve becomes narrowing and disappeared as the medium temperature increase. Uniform corrosion is the main way found on the surfaces of the stainless steels at room temperature in the hydrochloric acid solution. However, the selective corrosion occurs on their surface with the medium temperature increasing, and the higher temperature and concentration of corrosion medium, the more serious selective corrosion.
Research on the Formation Mechanism of Emulsion Spots on the Cold-Rolled Silicon Steel Surface
Authors: Li Yan , Sun Jian Lin , Chen Jing Yue
Published: March 2016

For the cold-rolled silicon steel strip lubricated with emulsion, the typical oil spot defects always can be found on the surface of rolled strip. The oil spot are parallel to the rolling direction. In the present study the micro-structure of oil spot defects was investigated by several surface analysis techniques, including LEXT ols4000 laser scanning confocal microscope, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS). The chemical compositions of the oil spot defects were analyzed by EDS. The results showed that the surface quality of the rolled non-oriented silicon steel was affected strongly by emulsion stability. The emulsion stability decreased with the increasing content of CL-. When the particle size of emulsion was larger, the lubricity of the emulsion deteriorated. Furthermore, there were some emulsions which contain miscella on the strip steel surface. The emulsions existed in the confined areas where the plate shape defects formed. The majority of its water was evaporated with the increasing of temperature and time. The oxides and residual emulsions could be found on the surface strip steel, which originated from the oxidation reaction between vapors and silicon steel surface. Eventually, the reaction produced some oxides (Fe3O4, FeO, Fe2O3, SiO2, CoCr2O4, NiCr2O4, Fe-Cr) and other by-products. In addition, the emulsion spots area were easier to suffer corrosion than the normal area under the same conditions.
Influence of Processing Procedure on Mechanical Properties of A319 by Comparison between Casting and Powder Metallurgy
Authors: Gao Feng , Xu Cong , Ji Guo Fu , Yang Ming Ju , Ma Chao Li
Published: March 2016

Al-6wt.%Si-3.5wt.%Cu alloy (A319) were prepared by casting and powder metallurgy (PM) methods to investigate the influence of processing procedure on properties. The casting samples were cast into a horizontal mold after degassing by argon. The PM samples were extruded after hot-press sintering before which Al-11wt.%Si master alloy powder, pure Al powder and 48 h ball-milled Al-40wt.%Cu powder were blended for 12 h at rotation speed of 250rpm. The samples underwent a T6 temper, i.e. solution, water quenching and artificial aging. Microstructures were observed by optical microscope (OM) and scanning electron microscope (SEM), and phases were determined by X-ray diffraction (XRD). The tensile testing was carried out on universal testing machine. The results showed that heat treatment could greatly improve the tensile strength of the samples, especially for the casting counterpart. Discussion was made to analyze the reason that the properties differed.
Constraint Effect on the Ductile Fracture Behavior of High-Strength Pipeline Steels
Authors: Xu Jie , Zhuo Xiao Min , Li Peng Peng , Fan Yu , Sun Zhi
Published: March 2016

This work presents an investigation of the ductile tearing properties for a pipe with internal and external circumferential cracks using 2D plane strain and axisymmetric models. Crack growth resistance curves were computed using the complete Gurson model. The pipes with various crack depths and internal pressures were analyzed. The results were compared with those of corresponding SENT and SENB specimens. It clearly indicated a significant effect of constraint on the resistance curves for internal and external cracked pipes. A minor effect of hoop stress induced by internal pressure on the CTOD-resistance curves is expected for deep-cracked pipes. The SENT specimen is a better representation of circumferentially flawed pipes and an alternative to the conventional standard SENB specimen for the fracture mechanics testing in engineering critical assessment of high-strength pipeline steels.
Microstructure and Properties of Weld CGHAZ under Different Heat Input for X90 Pipeline Steel
Authors: Yang Liu Qing , Sui Yong Li , Xia Pei Pei , Zhao Hai Hong , Yin Zhang Hua
Published: March 2016

Two kinds of industry trial X90 pipeline steels which have different chemical composition were chosen as test objects, and the grain coarsening, microstructural characteristics and the variation rules of low-temperature impact toughness in weld CGHAZ of this two steel under different welding heat input were studied by physical thermal simulation technology, SEM, optical microscope and Charpy impact tests. The results showed that the microstructure in weld CGHAZ of 1# steel was mainly bainite ferrite (BF) and most of the M/A constituents were blocky or short rod-like; the grains of 2# steel were coarse and there was much granular bainite (GB). Meanwhile M/A constituents became coarser and their morphology changed from block to long bar; alloy content of X90 pipeline steel under different weld heat input had great effect on the grain size of original austenite. When heat input was lower than 20KJ/cm, the impact toughness in CGHAZ of lower alloy content pipeline steel was good; as heat input increased, impact toughness in CGHAZ of 1# steel increased to the values between 260J and 300J when heat input was between 20KJ/cm and 25KJ/cm and the dispersion of impact energy was small. The impact toughness of 2# steel decreased gradually and the impact energy had the obvious dispersion.
Output-Only Identification of Vibratory Machine Suspension Parameters under Exploitational Conditions
Authors: Iwaniec Joanna , Iwaniec Marek
Published: March 2016

The paper concerns model based identification of vibratory machine body suspension system on the basis of dynamic responses measured under exploitational conditions. The research was carried out by means of the restoring force, boundary perturbation and direct parameter estimation techniques which, on the contrary to classical nonlinear system identification methods, requires neither excitation measurements nor linear behaviour of the considered system around an operating point. At the first stage of the research, parameters of the machine body suspension system were identified. Results accuracy was verified by determining percentage relative error of mass estimation with respect to the value calculated based on the machine geometrical and material properties. In the next step, the suspension system was modified by introduction of a nonlinear damping system. Obtained results proved that the assumed identification method is convenient for vibratory machine suspension condition monitoring and determining forces transferred on machine foundations.
Rock Bolts Health Monitoring Using Self-Excited Phenomenon
Authors: Kwaśniewski Janusz , Dominik Ireneusz , Lalik Krzysztof , Korzeniowski Waldemar , Zagórski Krzysztof , Skrzypkowski Krzysztof
Published: March 2016

Health monitoring of rock bolts can indirectly indicate the state of rock which is crucial for mining safety. This paper presents an innovative application of the Self-excited Acoustical System SAS for stress change measurement in rock bolts which are used to secure roofs and walls in mines and tunnels. The method gives information on the change of rock stress in the immediate area next to the bolt. It can be used also to determine the necessity of the exploited bolt replacement.
Active Rejection of Harmonic Disturbances with Nonstationary Harmonically Related Frequencies Using Varying-Sampling-Time LPV Control
Authors: Shu Xin Yu , Ballesteros Pablo , Bohn Christian
Published: March 2016

This paper presents a method for the active noise and vibration control (ANC/AVC) of harmonically related nonstationary disturbances using varying-sampling-time linear parameter-varying (LPV) controller. The frequencies are assumed to be known and varying within given ranges and they are multiples of one fundamental frequency.
The System for Active Control of Sound Transmission through a Window Panel – The Concept and Simulation Results
Authors: Morzyński Leszek , Zawieska Wiktor Marek , Krukowicz Tomasz
Published: March 2016

High acoustic insulation windows are common mean to decrease sound transmission to closed spaces. Hence, the improvement of sound insulation of windows is very important research issue. In this paper partial results of research project aimed at synthesis of the window panel with actively controlled sound transmission are presented. Recent stage of the project is focused on the development of multichannel Active Structural Acoustic Control algorithm. High amplitude excitation produces nonlinear vibration effects. Using feedforward control strategy it is convenient to control not only the reference signal spectrum, but also additional frequencies generated as the cause of nonlinearity. Therefore neural network based algorithm is considered. To lower the computational burden of the algorithm, round robin based error backpropagation learning is employed. The results of numerical simulations are presented. Major conclusion of presented part of the research is that the algorithm is capable of controlling a wide-band noise efficiently. Reduction of the computational complexity leads to increased convergence time, not influencing the final value of mean square error.