bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation and Process Optimization of Directional Solidification of Nb Containing High Silicon Steel
Authors: Yang Kun , Ye Feng , Liang Yong Feng , Lin Jun Pin
Published: March 2013

Fe-6.5%Si alloy is an excellent soft magnetic material. However, the industrial production of this sheet was difficult, due to its room temperature brittleness. In order to improve its deformation performance, the directional solidification and inhibitor of Nb were investigated in this study. Rod samples of Φ6.8 mm×100 mm were used both for modeling and experiments. ProCAST-finite element analysis was employed for the modeling with a temperature gradient of 1150K/cm (from 1450°C to 300°C) for directional solidification and the drawing velocities of 10, 35, 60, and 100μm/s. Calculations were carried out on the concerning temperature gradient, solidification rate and grain growth. The results showed that small amount of Nb, with optimized drawing velocity of 60μm/s was helpful for the homogeneity of grain size, which could improve the ductility for subsequent deformation processes.
Fabrication of Carbon Fiber Reinforced Magnesium-Based Composite Laminates by Vibration Assisting Hot Pressing
Authors: Liu Shen Yang , Zhang Jian Jun , Liang Wei , Bian Li Ping , Li Xian Rong
Published: March 2013

Carbon fibers reinforced AZ31 composite laminates were fabricated by vibration aided mechanical hot pressing. Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze their phase components and microstructure. The interfacial bonding strength was measured by uniaxial tension testing. The results showed that Mg-Zn-Al eutectic alloy solder had a strong bonding with carbon fibers and a noticeable diffusion with AZ31 alloy. No debonding was observed on the interface of carbon fibers, and no carbide was detected in this system. The bonding strength of composite laminate reached up to ~17.48MPa which was close to the bonding strength of AZ31/Al composite laminate. It was indicated that vibration assisting hot pressing was a feasible technique for the fabrication of Mg-based composite laminates reinforced with uncoated carbon fibers.
Microstructures and Mechanical Properties of ZK60-XHo Wrought Magnesium Alloys
Authors: Huang Zheng Hua , Qi Wen Jun , Xu Jing
Published: March 2013

Microstructures and phase compositions of as-cast and extruded ZK60-xHo (x=0~5) alloys were analyzed by X-ray diffraction, differential scanning calorimetry, optical microscope, scanning electron microscope and transmission electron microscope. Meanwhile, tensile mechanical property and impact toughness were tested. The results showed that as-cast microstructure was refined gradually with increasing the Ho content. Mg-Zn-Ho new phase increased gradually, while MgZn2 phase reduced gradually to disappear. Second phase tended to distribute along grain boundary by continuous network. As-cast tensile mechanical property remained almost unchanged and impact toughness value αnK was low (9~17 J/cm2). After extrusion by λ=40/T=593 K, grain size reached the micron level (1~5 μm) and broken second phase distributed dispersedly. Extruded tensile mechanical property was enhanced obviously. Tensile strength σb at ambient temperature increased gradually from 355 MPa for ZK60 alloy to 375 MPa for ZK60-4.77Ho alloy, while elongation δ decreased gradually from 19.5% to 12.5%. σb at 473 K increased gradually from 120 MPa to 169 MPa. Meanwhile, αnK was enhanced to 26~54 J/cm2. Fine grain and few fine dispersed second phase enhanced the tensile mechanical property and impacted toughness of magnesium alloys effectively.
Precipitation Behavior and Microstructure Evolution of Mg-Zn-Zr-Er Alloy Processed by Secondary Deformation and Heat Treatment
Authors: Zhang Bao Xiang , Zhang Jing
Published: March 2013

Preheated at 673K for 3h and 6h respectively, as-extruded Mg-9Zn-0.6Zr-2Er (wt.%) slabs with starting thickness of 8mm were hot-rolled at 673K to 2mm. The hot-rolled alloys were then solution treated at 673K for1.5h and aged at 473K for 10h. Microstructure evolution and second phase precipitation behavior during hot rolling and subsequent heat treatments were examined by optical microscopy (OM), scan electron microscopy (SEM) and micro hardness test. Mg-9Zn-0.6Zr-2Er alloy were fully recrystallized with fine equiaxed grains after preheating for 3 hours, prolonging heating time leads to a higher degree of dissolution of secondary phase into Mg matrix but a coarsening of the microstructure. During hot rolling process, the volume fraction of the DRX grains increased gradually with increasing reduction ratio, shearing bands became visble in the final pass. Thermal stable Mg-Zn-Er intermetallic compounds distributed along rolling direction at the first rolling passes and became more homogenous in the final pass. More nanosized MgZn2 precipitated during hot rolling in the alloy preheated for 6h than that for 3h, leading to an enhanced precipitation hardening effect in the former.
Microstructure Transformation of a Refined High Nb Containing TiAl Alloy
Authors: Chai Li Hua , Yang Liang , Zhang Jian Peng , Zhang Zhi Yong , Zhang Lai Qi , Lin Jun Pin
Published: March 2013

High Nb containing TiAl alloys have been investigated traditionally as potential high temperature structural materials because of their high strength, good oxidation and creep resistance. However, the poor ductility and fracture toughness at room temperature limit their application, which could be improved by controlling microstructure to get refine and homogeneous fully lamellar structure. In this study, a high Nb containing TiAl alloy alloying Mn, B and Y with refined microstructure was produced. The solidification path was analyzed by DSC and SEM microstructure of the alloy was observed, after heating at a certain temperature for 1-24hrs and then quenching in water. The dissolution of β phase was also investigated. The results showed that the β phase could decompose only by heating in single β or near α phase field.
Effects of Solid Solution Treatments on Microstructures and Tensile Properties of a Mg-Y-Zn-Cu Alloy
Authors: Shi Bing Qing , Chen Rongshi , Ke Wei
Published: March 2013

In this study, a Mg-2.1Y-0.5Zn-0.6Cu-0.1Zr (WZC200, in at. %) alloy was prepared by permanent casting method. On the basis of thermal analysis results during solidification process, two temperatures (T1/763K and T2/773K) were selected for subsequent solid solution treatments. Microstructure evolution and the tensile property changes after T4 treatment at T1 and T2 for different holding time were also investigated in this study. The tensile testing results showed that yield strength and ultimate tensile strength were improved with the fraction increase of the lamellae-shaped LPSO phase in the grain interiors, rather than the total fraction of LPSO phase.
Microstructure and Mechanical Properties of Extruded AZ31 Profile with High Performance
Authors: Yu Bao Yi , Gao Tian Jiao , Li Qi , Wu Yu Juan , Li Run Xia
Published: March 2013

Based on the advantages of Mg alloys, AZ31 alloy profiles were designed for mobile phones cell, and cars, which expanded Mg alloy application and achieved the purpose of environmental protection and energy saving. Tensile strength of the profile reached to 256 MPa, and elongation was 17.9%. The effects of different heat treatment parameters on microstructure and plastic property of AZ31 alloys profiles were studied. After aging heat treatment (T5), the comprehensive mechanical properties at room temperature of the profiles increased. The tensile strength reached to the maximum of 261 MPa, and the elongation reached to 14.3%, after ageing at 225 for 20h. The elongation reached the maximum value of 18.3%, however, the tensile strength decrease to 241 MPa, after aging at 175 for 15h. Moreover, the influence of cryogenic treatment on microstructure and plastic property of the AZ31alloy profiles were studied. The results showed that elongation increased with the increase of treatment time, which would reach to 18.5% after cryogenic treatment. In addition, by cryogenic treatment and aging treatment, the tensile strength improved to 271 MPa. The cryogenic treatment improved obviously the plastic ability of AZ Mg alloys, while normal heat treatment improved it unobviously.
Tensile Properties of a Low-Cost First Generation Single Crystal Superalloy DD16
Authors: Xu Jian Wei , Zhao Yun Song , Tang Ding Zhong
Published: March 2013

The tensile properties of a low-cost first generation single crystal superalloy DD16 have been investigated. The results show that values of the tensile strength and yield strength of DD16 alloy were similar at typical temperatures; from room temperature to 760, the yield strength of DD16 alloy increases; However, above 760, the yield strength of DD16 alloy decreases remarkably, and the maximum of the yield strength was 1145.5MPa at 760. From room temperature to 760, the fracture mode was cleavage fracture; But above 760, the fracture characteristics changed from cleavage to dimple.
Numerical Analysis of Superplastic Bulging Process of TiAl Sheet
Authors: Wang Chuan Yun , Li Jin Shan , Tang Bin , Kou Hong Chao
Published: March 2013

The superplastic bulging process of TiAl sheet was simulated by coupling superplastic constitutive equation to finite element model. Based on this model, the effect of coefficient of friction between the sheet and mold and the size of the mold fillet on the superplastic bulging (SPB) performance of TiAl alloys sheet were studied by analyzing the evolution of equivalent plastic strain and thickness distribution in the sheet. The results showed that friction was the dominant factor of the nonuniform thickness of the sheet, while higher friction and smaller radius of mold fillet inhibited the over-thinning of sheet on the entry of mold cavity. The simulation results were in good agreement with the experimental results. Therefore, the present model could be used for optimizing the selction of the deformation parameters and the design of the structures.
Effect of Salt-Coating Hot Corrosion on Stress-Rupture Properties of a Corrosion Resistant Directionally Solidified Superalloy
Authors: Chen Xue Da , Li Qing , Xiao Cheng Bo , Ren Wei Peng
Published: March 2013

The hot components of gas turbine are loaded by high stresses in presence of high-temperature oxidation and hot corrosion environment during service process. It is important to simulate the interaction of stress and hot corrosion on the components in real service situation. Effect of the ratios of salt mixtures of Na2SO4/NaCl and the coating amounts of salt mixtures on the microstructure and the high temperature stress-rupture properties of a corrosion resistant directionally solidified superalloy at 850/500MPa were investigated. The results demonstrated that the stress-rupture life decreased with the coated salt mixture ratio of Na2SO4/NaCl changing from 3:1 to 9:1. Stress-rupture lives of the alloy decreased from 63 h to 42 h, while the coated salt mixtures amount increased from 1 mg/cm2 to 4 mg/cm2, hereby the salt mixture contained 75% Na2SO4 and 25% NaCl. When the coating ratio of Na2SO4/NaCl was 9:1, the stratified corrosion products layers were composed of the (Ni, Co)O, Ni (Al, Cr)2O4 layer, bright grey phase that be identified as CrWO4, and the underlying dispersed particle shape phase CrSx, the underlying layer forms the sulfides eutectic and leads to catastrophic destruction for the alloy, which decreased the stress-rupture lives dramatically.
Effects of Consolidation Process on the Microstructure and Mechanical Properties of ODS Ferritic Alloy
Authors: Liu Tong , Shen Hai Long , Zhang Tong Wen , Zhu Mu , Qin Cheng Gong
Published: March 2013

The oxide-dispersion-strengthened (ODS) ferritic alloy powders (Fe-14Cr-3Al-2W-0.1Ti-0.35Y2O3) were prepared by mechanical alloying (MA) at a rotation speed of 720 rpm for 24 h. All the elements were mixed homogenously in the powder, and Cr and Al dissolved in α-Fe after MA. The bulk samples were produced by spark plasma sintering (SPS) at 950 and 50 MPa and by hot isostatic pressing (HIP) at 1150 and 130 MPa, respectively. The SPS sample showed a tensile strength of 730 MPa and a poor ductility due to the existence of pores in microsize. The HIP sample had a high tensile strength of 980 MPa, yield strength of 710 MPa and elongation of 10.3 %. The excellent mechanical properties of the HIP sample was due to the small grain size of the matrix of about 400 nm and the fine oxide particles of 5-40 nm.
Surface Segregation and Oxidation Behavior of Superalloy Powders Fabricated by Argon Atomization
Authors: Gao Zheng Jiang , Zhang Guo Qing , Li Zhou , Yuan Hua , Xu Wen Yong , Zhang Yong
Published: March 2013

Particle surface component and valence state of nickel-based superalloy FGH96 powders fabricated by argon gas atomization have been measured by X-ray phoelectron spectrometer (XPS) to recognize the effect of powder size, surface segregation and heat treating on the oxidation behavior of powders. Type and phase structure of prior particle boundaries (PPBs) precipitated in HIPed superalloy have been studied also. The results showed that prior particle surface segregation and oxidation happened during the powder collection and storage with the C, O, Ti elements enrichment and Ti, Cr, Al, Zr elements oxidation in the surface respectively. During the heat treating of 1150/2h, normal segregation element Ti and Zr enriched more apparently in the particle surface, on the contrary, negative segregation elements Ni, Al and Co diffused into the particle inner. Furthermore, the higher oxygen level on particle surface enhanced to form much more oxides such as ZrO2, TiO2 and Cr2O3. During HIP process of 1150/2h/150MPa, the oxide ZrO2 as the nuclei accelerated the preferential precipitation of MC-type carbides which forms the continuous harmful PPBs. Definitely, PPB precipitation depended on the prior particle surface segregation and oxidation, surface elements Ti, Cr and Nb enrichment and oxidation reaction enhancement in high temperature such as 1150. Small powders always had little segregation in the surface and thin oxidation layer, but had more oxygen content per weight for its higher specific surface. So using some powders with optimum particle size and lower oxygen content can help to reduce the PPB precipitation.
Constitutive Characteristic of Hot Deformation for Spray Formed Superalloy GH738
Authors: Wang Yue , Li Zhou , Xu Wen Yong , Yuan Hua , Liu Na , Gao Zheng Jiang , Tian Shi Fan , Zhang Guo Qing
Published: March 2013

The hot deformation behaviors of spray formed superalloy GH738 were investigated by using of Gleeble-3500 simulator in the temperature range of 950~1200, with a strain rate of 0.13~6.5s-1 and reduction of 50%. The corresponding flow curves were determined and hot deformed microstructures were observed. The results showed that the flow stress decreased with increasing deformation temperature or decreasing strain rate. A full dynamic recrystallization microstructures with fine-equiaxed grains were obtained at the temperature of 1100~1150 and strain rate of 2.6~6.5s-1. The hot deformation activation energy Q was 580.81kJ.mol-1, and the constitutive equation was derived by means of linear regression.
Effect of Nb Addition on the Corrosion Behavior of Porous TiAl Based Alloys in Aqueous Environments
Authors: Yang Fan , Li Xiao , Tian Nan , Liang Yong Feng , Lin Jun Pin
Published: March 2013

The corrosion behavior of porous Nb-containing TiAl based alloys in HCl, NaOH and NH3H2O aqueous solutions with various concentrations has been studied simultaneously at room temperature. The results indicate that the porous alloys have good acidic resistance which is probably based on the combined work of Ti-Ti metallic bond and covalent bond. And pitting corrosion is the main corrosion behavior of Nb-free TiAl alloys during the first 40 hours, while intergranular corrosion is the main corrosion behavior later. Nb-containing alloys have better acid corrosion resistance due to inhibiting intergranular corrosion by Nb element. In addition, the porous TiAl based alloys are much more resistant to corrosion in alkaline solutions than in acidic solutions, owing to the different oxide films formed in alkalis solutions.
Effect of Cr and Re on the Oxidation Resistance of Ni3Al-Base Single Crystal Alloy IC21 at 1100
Authors: Xu Xiao Jing , Wu Qiong , Gong Sheng Kai , Li Shu Suo
Published: March 2013

The oxidation kinetic curves of three Ni3Al-based single crystal alloys (IC21, IC21C and IC21CR) with different Cr and Re content were examined at 1100. The microstructures and element distributions of the oxide scales on these alloys were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectrometry (EDS). Results revealed that the oxidation resistance of these alloys was improved in the order of IC21 < IC21C < IC21CR. The oxide products of IC21 mainly consisted of NiO, α-Al2O3, NiAl2O4 and a small amount of NiMoO4 and MoO2. The volatilization of Mo oxides led to the oxide scale spallation from IC21C, thus deteriorated the oxidation properties. While for IC21C and IC21CR, the oxidation resistance was significantly improved. The Mo oxides in the oxide layer were greatly reduced and a continuous α-Al2O3 layer was formed.
Improvement in Oxidation Resistance of Ni3Al Based Single Crystal Superalloy IC32 by NiAlHfSi Coating
Authors: Dai Peng Chao , Peng Hui , Pei Yan Ling , Ma Yue , Li Shu Suo , Gong Sheng Kai
Published: March 2013

In order to improve the oxidation performance of IC32, the NiAlHfSi coating was deposited on the alloy by electron beam physical vapor deposition (EB-PVD) method. The oxidation resistance of the coated alloy at 1423 K was investigated. The microstructures of the samples before and after oxidation were examined by SEM, XRD and EPMA. It was found that the oxide scales compactly formed on the surface of the coating, and the oxidation mainly consisted of Al2O3 and NiAl2O4. Phase transformation occurred from β-NiAl to γ-Ni3Al in the coating after oxidation for extend periods. The diffusion and oxidation of Mo were prevented effectively by the coating, which improved the oxidation performance of IC32 significantly.
Preparation of Oxide Dispersion Strengthened Fe by Co-Precipitation
Authors: Guo Zhi Meng , Yang Wei Wei , Luo Ji , Yu Xiao
Published: March 2013

Oxide dispersion strengthened (ODS) materials have received extensive attention due to their excellent resistance to high temperature creep, fatigue, corrosion and radiation damage. In this paper, the ODS iron powder is prepared by co-precipitation. The oxide dispersion strengthened iron was prepared by spark plasma sintering (SPS) from the ODS iron powder. The microstructure and mechanical properties of the materials were investigated by Scanning Electron Microscope and micro-electronic universal tester. The results reveal the Al2O3 dispersion of ODS iron powder by co-precipitation is uniform and the mechanical properties are excellent.
Intrinsic Brittlement of Mo3Si by First-Principle Calculations
Authors: Zhang Lai Qi , Du Wei , Wang Meng , Hou Yong Ming , Ni Xiao Dong , Lin Jun Pin
Published: March 2013

First-principles method has been used to study the intrinsic brittlement of Mo3Si. The crystal constants, formation energy, cohesive energy, electronic structure, elastic constants of Mo3Si were calculated. The results were in good agreement with experiment data. Electronic structures showed that the strong covalent bonding between the nearest neighbour Mo atoms, which arrange perpendicularly each other, leads to embrittlement of Mo3Si.
Self-Propagating Combustion Synthesis and Characterization of ODS Fe-Base Superalloy Powders
Authors: Chen Cun Guang , Guo Zhi Meng , Luo Ji , Yang Wei Wei , Hao Jun Jie , Yang Jian
Published: March 2013

A new method was employed to synthesize nanosized Y2O3 dispersion strengthened Fe-base superalloy powders using self-propagating combustion. A concentrated solution of nitrates of iron and yttrium was used as oxidizer, malic acid as fuel to fabricate Fe2O3/Y2O3 powders at low temperature. Afterwards, uniform and fine Fe/2wt.%Y2O3 powders were obtained by selective reduction with hydrogen, on the surface of which dispersive Y2O3 particles of the mean size of 30 - 50 nm were observed.
Influence of Ageing Treatments on Stress Rupture Properties of Ni3Al-Base Single-Crystal Alloy IC21 at 850°C
Authors: Li Hui , Li Fu Lin , Li Shu Suo , Zhang Heng , Gong Sheng Kai
Published: March 2013

The influence of three different ageing treatments (R1:1100/2h,air cooling+870/32h,air cooling, R2: 870/32h,air cooling and R3: 1060/2h,air cooling+870/32h,air cooling) on stress rupture properties of Ni3Al-base single-crystal alloy IC21 was investigated. The results indicate that ageing heat treatments have obvious effects on stress rupture properties of IC21 at 850/500Mpa. After R3 ageing treatment, IC21 alloy presents the longest rupture life and the smallest ellipticity and elongation compared to those after the other two ageing treatments. Microstructure examination shows that the mean size of γ precipitate is about 0.44μm after R3 ageing heat treatment (1060/2h, ac + 870/32h, ac). Transmission electron microscope (TEM) study on the rupture samples illustrates that after R1 and R2 ageing heat treatments, the density of stacking faults increases and the length is larger compared to that after R3 heat treatment. Meanwhile the shearings of γ precipitates are more severe. The appropriate γ phase size and γ channel width after R3 treatment promote homogenous deformation by <110>{111} slip in the matrix, and facilitate the formation of finer dislocation networks on the γ/γ interface, which can restrain the shearing of γ phase by dislocations.
Heat Treatment of a Ni3Al-Based Single Crystal Alloy IC32
Authors: Cui Dong Liang , Xie Xiao Ying , Li Shu Suo , Zhang Heng , Gong Sheng Kai
Published: March 2013

C32 is a new type of Ni3Al-based single crystal alloy, which has been designed to serve at 1200. The effect of heat treatment on the microstructure of single crystal superalloy IC32 was investigated. The microstructure after heat treatment under different solution and aging temperature was examined by using optical microscope (OM), scanning electron microscopy (SEM) and electron probe microscopic analyzer (EPMA). The as-cast microstructure of IC32 consisted of a two-phase γ/γ microstructure, and primary bulky γ phase which priciptated in the interdendritic region. The incipient melting temperature of IC32 is 1360, and the heat treatment window is about 40. Considering high contents of refractory elements Re and Ta, a complicated 18 hours solution heat treatment at different temperatures was conducted to elimate the segregation and dissolove the primary bulky γ phase. The optimum heat treatment of IC32 alloy is 1325/4h+1335/4h+1345/10h, ac + 1165/2h, ac + 870/32h, ac.
Effects of Long-Term Aging Treatment on Stress Rupture Properties of FGH95 Ni-Base Superalloy
Authors: Tian Su Gui , Xie Guang Liang , Xie Jun , Zhou Xiao Ming
Published: March 2013

The effect of long-term aging on stress rupture properties was investigated by means of microstructure observation and properties measurement. The results showed that, after long-term aging for 500 h at 723 K, the coarser particle-like γ phase was precipitated along the grain boundaries of alloy, significant amount of γ particles were regularly distributed within the grain. Moreover, some carbide particles precipitated depressively along the boundaries and within the grain. As the aged time and temperature increased, the size of fine γ particles in the alloy increased slightly, and the stress rupture property of the alloy decreased under the condition of 923K and 1034MPa. The deformation features of the alloy during creep were that the dislocations slip in the matrix or shear into the γ phase, the dislocations shearing into the γ phase may be decomposed to form the configuration of the two partial-dislocations plus stacking fault. As the creep went on, the slipping traces with different orientations appeared in the surface of the specimen, and some slipping steps were formed in the region near the boundaries, which may cause the stress concentration to promote the initiation and propagation of the cracks along the boundaries up to creep fracture.
Microstructure and Creep Property of DZ125 Nickel-Based Superalloy
Authors: Tian Su Gui , Meng Xian Lin , Tian Ning , Yu Hui Chen
Published: March 2013

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.
Thermal Deformation Behavior and Constitutive Equation of Highly Alloyed Superalloy Udimet720Li
Authors: Wang Tao , Fu Shu Hong , Li Zhao , Zhang Yong , Zhao Yu Xin , Guo Ling
Published: March 2013

Hot compressive deformation of Udimet720Li alloy was carried out on Gleeble-3500 thermal mechanical simulator. The flow stress behavior of Udimet720Li alloy during hot compression was studied in the temperature range of 1100-1160 and at a strain rate of 0.001-1s -1. The results showed that the flow stress was controlled by both strain rate and deforming temperature. The flow stress decreased with the increase of deforming temperature, while increased with the increase of strain rate. The change of flow stress with deformation thermal parameters was revealed from true stress-true strain curves, and constitutive relationship of Udimet720Li alloy was obtained on the base of Arrhenius equations and the deformation activation energy was calculated.
Study on the Properties of Spray Formed Tool-Die Steel
Authors: Zhang Yong , Zhang Guo Qing , Li Zhou , Ni Xin Lei
Published: March 2013

The T15 high speed steel (HSS) spray formed (SF) billets were manufactured using a twin-atomizer spray forming facility at Beijing Institute of Aeronautical Materials (BIAM) AVIC, China. The billets were then hot isostatically pressed (HIP) following hot forge (HF) and heat treatment (HT). The as-spray formed billet is integrally dense and has a high relative density of >98%, and the macrostructure is free of macrosegregation. The microstructure consists of polygonal grains of 20µm with tempered martensite inside the grains and refined carbides uniformly distributed along the grain boundaries. Hardness and three-point bending properties were also measured. The spray formed materials was comparable to those made by powder metallurgy in terms of microstructure uniformity, hardness and bending property.
Stress Corrosion Cracking (SCC) of Nickel-Base Weld Metals in PWR Primary Water
Authors: Xiong Ru , Qiao Ying Jie , Liu Gui Liang
Published: March 2013

This discussion reviewed the occurrence of stress corrosion cracking (SCC) of alloys 182 and 82 weld metals in primary water (PWSCC) of pressurized water reactors (PWR) from both operating plants and laboratory experiments. Results from in-service experience showed that more than 340 Alloy 182/82 welds have sustained PWSCC. Most of these cases have been attributed to the presence of high residual stresses produced during the manufacture aside from the inherent tendency for Alloy 182/82 to sustain SCC. The affected welds were not subjected to a stress relief heat treatment with adjacent low alloy steel components. Results from laboratory studies indicated that time-to-cracking of Alloy 82 was a factor of 4 to 10 longer than that for Alloy 182. PWSCC depended strongly on the surface condition, surface residual stresses and surface cold work, which were consistent with the results of in-service failures. Improvements in the resistance of advanced weld metals, Alloys 152 and 52, to PWSCC were discussed.
Relationship between Intragranular α Phase Width and Microhardness of TC18 Titanium Alloy
Authors: Li Hong Hua , Wu Guo Qing , Shi Cheng Long , Sha Ai Xue
Published: March 2013

Four typical microstructures of TC18 titanium alloy (Widmannstatten structure, Fine basketweave structure, Bi-model structure, Coarse basketweave structure) were investigated, including the changes of intragranular α phase width and the relationship between intragranular α phase width and microhardness. The results show that the intragranular α phase width of the four typical microstructures varies greatly in accordance with the order from smallest to largest: Widmannstatten structure < Fine basketweave structure < Bi-model structure < Coarse basketweave structure. The microhardness of the TC18 titanium alloy reduces with the increase of intragranular α phase width.
β Grain Growth Kinetics of a New Metastable β Titanium Alloy
Authors: Fei Yue , Wang Xin Nan , Zhu Zhi Shou , Li Jun , Shang Guo Qiang , Zhu Li Wei
Published: March 2013

Ti-Mo-Nb-Cr-Al-Fe-Si alloy is a new metastable β titanium alloy with excellent combination of strength and ductility. The β grain-growth exponent and the activation energies for β grain growth for the investigated alloy at specified temperature were computed by the kinetic equations and the Arrhenius-type equation. The rate of β grain growth decreases with elongating solution treated time and increases with the increasing solution-treated temperature. The β grain-growth exponents, n, are 0.461, 0.464 and 0.469 at 1113, 1133 and 1153K, respectively. The β grain growth activation energy is determined to be 274 KJ/mol.
Research on TC4 Alloy Wire Rod Straightening Process
Authors: Feng Jian Chao , Chen Ming He , Zhang Chao , Guo Li Ming
Published: March 2013

Titanium alloy are widely used in various fields, such as Aerospace, Marine and Medical. However, the technology of straightening for TC4 wire rod has not been effectively solved, and relevant research is quite rare. TC4 wire rod is difficult to be straightened under room temperature owing to its special properties. In order to solve this problem, this paper designed a parallel roll thermal straightening system and also developed an automatic intermesh calculation software based on Matlab GUI platform to precalculate the settings of straightening device under different temperatures according to straightening theory. Furthermore, numerical simulation method has been used for straightening process with ABAQUS software before the practical straightening experiment. Finally, using the calculated parameters the straightening experiment was carried out, and results show that this method is feasible and effective.
Study on Combustion Behavior of TC4 and Ti40 Alloys
Authors: Huang Ming Yue , Xin She Wei , Ju Jian Hui , Lu Ya Feng , Li Qian , Zhao Yong Qing , Wang Biao
Published: March 2013

Abstract. OM, XRD, SEM, EDS were used to test. and analyze the combustion products of TC4 and Ti40 alloys by layer-by-layer from reaction frontier to matrix The result shows that: titanium alloy can be divided into 4 sections, combustion surface (CS), molten zone (MZ), transitional zone (TZ) and influence zone (IZ). The CS is mainly consist of TiO2, and with oxide of V. Cr2O3 and SiO2 are detected on CS of Ti40. MZ of TC4 is in loose and porous state. There are lots of cracks and holes in the TZ and IZ; MZ of Ti40 is compact, between MZ and IZ there is a TZ which is rich of V and Cr, it can stop oxygen diffusing effectively. From the MZ to matrix, oxygen content reduces gradually, and oxide of Ti with different valence state is detected. Because of effect of oxygen, the hardness of the two alloy increase after combustion, increment of Ti40 is much greater than that of TC4.
Analysis of Hot Deformation Dynamics of TC18 Titanium Alloy
Authors: Wang Qing Rui , Sha Ai Xue , Li Xing Wu , Huang Li Jun
Published: March 2013

The effect of strain rate and deformation temperature on flow stress of TC18 titanium alloy was studied through heat simulating tests in 760~960 with temperature interval and the strain rate interval in 0.01~10s-1. Relationship model of flow stress versus strain was established and hot deformation mechanics of TC18 titanium alloy was analyzed. The results show that the flow stress reduces obviously as the deformation temperature increases or the strain rate decreases. Dynamic recovery occurs at high strain rate above phase transformation point, while dynamic recrystallization occurs at low strain rate as well as at the temperature below phase transformation point.
Designing Multi-Component β-Ti Alloys with Low Young's Modulus
Authors: Wang Qing , Zhang Xiang Dong , Li Xiao Na , Ji Chun Jun , Dong Chuang
Published: March 2013

[(Mo,Sn)(Ti,Zr)14]Nb1 serial alloy compositions were designed using a cluster-plus-glue-atom model to receive BCC β-Ti alloys with low Youngs modulus (E) in Ti-based multi-component systems, where the square brackets enclose the coordination polyhedron cluster CN14 of the BCC structure and Nb is the glue atom. These serial alloys were prepared into rods with a diameter of 6 mm by copper-mould suction casting method. XRD and tensile test results indicated that all these alloy series possessed a monolithic BCC structure except [SnTi14]Nb1 and [(Mo0.5Sn0.5)Ti14]Nb1 due to Sn deteriorating BCC structural stability. A combination of Mo0.5Sn0.5 at the cluster center, as well as low-E Nb and Zr in the glue and cluster shell respectively, can reach simultaneously low E and high BCC stability, incarnated in the [(Mo0.5Sn0.5)(Ti13Zr)]Nb1 alloy which has the lowest E of 48 GPa in the suction-cast state.
Experimental Study on Heat Yreatment Processing of a New Low Cost Titanium Alloy Used in Aviation Field
Authors: Shang Guo Qiang , Wang Xin Nan , Fei Yue , Li Jun , Zhu Zhi Shou , Zhu Li Wei
Published: March 2013

The effect of common solution treatment, two-step solution treatment and aging, solution treatment and aging (STA) on the microstructure and mechanical properties of a new low cost titanium alloy used in aviation field were investigated by optical microscope (OM), scanning electron microscopy (SEM) and tensile test. The results show that a typical equiaxed structure can be obtained by common solution treatment leading to a good combination of strength and plasticity. Besides, solution heat treating in the β region and subsequently ageing at a low temperature results in a significant increase in mechanical strength and a little decrease in plasticity. When the solution temperature is at α+β two-phase region (895), the low cost titanium alloy acquires the best combination of strength and ductility.
Microstructure and Property of a New Metastable β Titanium Alloy
Authors: Wang Xin Nan , Fei Yue , Zhou Xiao Hu , Zhu Zhi Shou , Li Jun , Shang Guo Qiang , Zhu Li Wei
Published: March 2013

The evolution regularities of microstructure and property of a new metastable β titanium alloy with different solution treatment and aging treatment were studied using optical microscope (OM), scanning electron microscopy (SEM) and tensile test. The results show that, the volume fraction of primary α phase decreases and globularization of α phase occurs with the increasing aging temperature from 540 to 580 and solution treated temperature from 800 to 820. When the solution treated temperature is 820, the acicular secondary α phase precipitates along β grain boundary. The strength of the investigated alloy increases and the ductility decreases with the solution treated temperature increasing. While the strength of the investigated alloy increases and the ductility decreases with the aging temperature decreasing.
β Stability and Mechanical Behavior of Metastable β Type TiNb Based Alloys
Authors: Liao Guang Yue , Guo Shun , Bao Zhen Zhen , Zhao Xin Qing
Published: March 2013

Metastable β type TiNb based alloys of Ti-35Nb, Ti-35Nb-4Sn and Ti-42Nb-4Sn (wt. %) with different stability were prepared and thermo-mechanical treatment was carried out to investigate their microstructural evolution and mechanical properties. It was found that although the TiNb based alloy with lower stability performs lower strength in its solution state due to the stress induced martensitic transformation, they could be strengthened significantly by severe cold rolling followed by aging, remaining a relative low elastic modulus. X-ray diffraction, transmission electron microscopy and mechanical test were conducted to characterize the microstructural evolution and mechanical behavior of the metastable β type TiNb based alloys with different β stability. The strengthening mechanism was discussed on the basis of the cold deformation and martensitic transformation.
The Effects of Rolling Process on the Microstructure and Properties of Columnar-Grained Cu-12 Wt%Al Alloys
Authors: Liu Ji Li , Huang Hai You , Xu Xu , Xie Jian Xin
Published: March 2013

Cu-12 wt.%Al (Cu-12Al) alloy fabricated by continuous unidirectional solidification (CUS) process has high elasticity, high strength, high conductivity, high plasticity and other good comprehensive properties, which has a potential to develop into a high-performance elastic material as the alternative to beryllium bronze. Especially, the room temperature tensile elongation of the columnar-grained structure (CGS) Cu-12Al alloy with high <001>β orientation along the axial direction exceeded 20%, which is six times more than that of the ordinary polycrystalline structure (OPS) Cu-12Al alloy (ε=2-4%) fabricated by traditional casting. The CGS Cu-12Al alloy shows lower flow stress and work-hardening rate during plastic deformation, which determines a dramatic improvement of workability comparing with the OPS alloy. In the present paper, both the effects of the rolling process and its parameters on the microstructure and properties of the CGS Cu-12Al alloy sheets were investigated. The results showed that the CGS sheets (σb=310 MPa, ε=19%) have the maximum reduction of 80% and remain columnar-grained structure after the first rolling pass at 700. After deformation the tensile strength was 401 MPa and the tensile elongation approached to 14%. Then, the hot rolled sheets were rolled again through the second pass at 325 and 700, respectively. The maximum reduction of CGS sheets at 325 warm rolling was 20%, the sheets remain columnar-grained structure and β1'α1' martensitic phase transformation occured; The second pass hot-rolling at 700 showed that the maximum reduction exceeded 60%, and the recrystallization occured in the sheets. After two passes of hot-rolling (total deformation was 92%), although the recrystallization occured, the CGS sheets remained columnar-grained structure (CGS) high tensile elongation (8.3%), which is two times more than that of the as-cast OPS sheets, and is five times as much as the OPS sheets with the same total deformation.
Effect of Mixing Method on Microstructure of SiCp/Al Composites
Authors: Cao Hui Qin , Guo Zhi Meng , Yang Wei Wei , Luo Ji
Published: March 2013

The fine and homogenous distribution of the SiC particles in Al metal matrix is basic prerequisite for improving the properties of the SiCp/Al composites. In this paper, the effects of high energy ball milling and ordinary ball milling on the spatial distribution of reinforcement of the SiCp/Al composites have been investigated. The result showed that high energy ball milling is the most effective method to get homogeneous distribution of SiC particles in Al matrix. There were many clusters of SiC particles in the composites fabricated by ordinary ball milling.
Study on the Interface Diffusion Bonding of the Copper Alloy/30CrMnSi Steel
Authors: Zou Jun Tao , Liu Yan Feng , Pei Lu , Wang Xian Hui , Liang Shu Hua
Published: March 2013

The copper alloy/30CrMnSi steel bi-metal composite materials were prepared by the interface diffusion bonding method. The diffusion of elements close to the bonding interface was studied and the formation and growth mechanism of dissolution layer were discussed as well. The results showed that a diffusion transition layer could be formed with the different widths for copper alloy/30CrMnSi steel integrated material. A diffusion transition layer was formed close to 30CrMnSi steel side due to the inter-diffusion of the alloy elements. The microstructure characterization showed that no harmful brittle phase presented around the interface, and two heterogeneous materials had a good metallurgical bonding.
Cryogenic Treatment of 06Cr19Ni10 Austenitic Stainless Steel
Authors: Zhang Hong , Gu Kai Xuan , Guo Jia , Xue Xiao Dai , Wang Jun Jie
Published: March 2013

The effect of cryogenic treatment on mechanical properties and wear resistance at room temperature of 06Cr19Ni10 austenitic stainless steel was studied in the present study. The cryogenic treatment process was carried out at-160 and different time in program-controlled cryogenic container. The results showed that, after cryogenic treatment, the room-temperature mechanical properties of the 06Cr19Ni10 steel remained stable without embrittlement, friction coefficient of the 06Cr19Ni10 steel decreased and the wear resistance improved after cryogenic treatment. When cryogenic treatment was treated at-160 for two hours and thirty minutes, the friction coefficient of the 06Cr19Ni10 steel was the smallest and wear resistance was the best.
The Study on the Reducing Friction and Anti-Wear Performance of Zinc Phosphate Nanoparticles as Lubrication Additives
Authors: Lv Yun Xia , Zhao Xiu Chen , Cheng Jing Wei , Liu Ying , Li Hong
Published: March 2013

Oleic acid-modified zinc phosphate nanoparticles with about 15nm particle size were synthesized by chemical deposition method. The tribological properties of the prepared nanoparticles as lubricant oil additives on MSR-10D four-ball tribotest were investigated. Results indicated that the lubricant oils adding oleic acid-modified zinc phosphate nanoparticles exhibited a good friction-reduction and anti-wear property. The zinc phosphate nanoparticle as lubricant oil additive had the optimum concentration. Friction coefficient decreased 14.2% maximally, and the wear-scar width reduced to 36.5% correspondingly, as compared to the base oil without nanoparticles. The results of the worn surface analysis with SEM and AFM showed that the zinc phosphate nanoparticles could deposit on the worn surface and separate the direct contact between the asperities of the worn surface, which was effective in the reduction of the plough and adhesion between asperities.
The Microstructural Evolution of AA6111 Aluminum Alloy during Homogenization Treatment
Authors: Zhang Shi Jiao , Xiong Bai Qing , Zhang Yon Gan , Li Xi Wu , Wang Feng , Li Zhi Hui , Liu Hong Wei
Published: March 2013

The microstructures of AA6111 automotive aluminum alloy were investigated by optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD) and transmission electron microscope (TEM). The results indicated that as-cast AA6111 alloy has a complex microstructure. There were many kinds of intermetallic phases, such as lath-shaped β-Al5FeSi, Al15(FeMn)3Si2and Mg2Si on the grain boundaries. The Al5Cu2Mg8Si6precipitates presented non-equilibrium eutectic morphology in the grain interiors. After homogenization treatment (6h at 470), the low melting point Mg2Si phase began dissolving. The eutectic Al5Cu2Mg8Si6phase were dissolved completely after 530/24h homogenization treatment. The Al15(FeMn)3Si2phase started to be spheroidized at 560. Increasing treatment temperature will promote Mn to substitute for Fe in this phase.
Effect of Cooling Paths on Microstructure and Mechanical Properties of Vanadium Bearing Microalloyed Steel
Authors: Chen Jun , Chen Xiang Wei , Tang Shuai , Liu Zhen Yu , Wang Guo Dong
Published: March 2013

Based on ultra fast cooling, effects of cooling paths on microstructure and mechanical properties of vanadium bearing microalloyed steel were investigated by the observation of optical microscope and scanning electron microscope and the testing of mechanical properties, moreover, the work-hardening exponent was determined based on stress-strain curves. The results show that using ultra fast cooling can effectively refine ferrite grain size and the ferrite grain size is decreased as the final temperature of ultra fast cooling is decreased. In addition, the microstructure and mechanical properties can be controlled by cooling paths. The ferrite-perlite microstructure with lower strength and higher n-value of approx. 0.2 and the ferrite-bainite microstructure with higher strength and lower n-value of approx. 0.16 can be gained at the higher and lower final temperature of ultra fast cooling, respectively. And the yield ratio are all lower than 0.85.
Effect of Partitioning Time on the Microstructure and Mechanical Properties of Q&P Steels
Authors: Ren Kang Kang , Kang Yong Lin , Zhu Shuai
Published: March 2013

The microstructure and properties of Q&P steel were studied by means of tensile test, OM and SEM after simulating heat treatment process in salt bath furnace. The results showed that the main microstructure of Q&P steel was lath martensite and retained film austenite. With the increase of partitioning time, the morphology of the parallel martensite lath became clear and ordered. With the trivialness and disorder with massive martensite appearing, the yield strengths and tensile strength decreased initially and then increased. On the other hand, the elongation increased initially and then decreased. This was because of that the retained austenite is unstable at the beginning for low carbon content, and the carbide precipitated after a long partitioning time. Therefore, there was an optimum partitioning time to obtain the best properties combination. Under 250 quenching temperature and 350 partitioning temperature, partitioning time was 60s, the tensile strength and elongation were 1027MPa and 27%, respectively. The product of strength and elongation was up to 27729MPa·%.
Effect of Different Concentrations of Sodium Silicate Impregnated on the Performance of Carbon/Copper Composites
Authors: Yang Hui Jun , Wang Heng Peng , Tang Bin , Qiao Jun Wei
Published: March 2013

Sodium silicate solution-impregnated carbon/copper composites were prepared from electrolytic copper powder, graphite particulate and pitch coke powder through compression molding, carbonization and impregnation. The effect of different concentrations of sodium silicate solution on their mechanical and tribological properties was studied. The results showed that the density of the composites increased monotonically with increasing the concentration of the sodium silicate solution. As did the bending strength and compressive strength, and they reached maxima of 47.78 MPa and 170.06 MPa at 30 wt. % of sodium silicate, respectively. The friction coefficient and wear rate of composite decreased monotonically with increasing the concentration of sodium silicate due to the formation of a lubricating film. The wear mechanism of the impregnated composites was abrasive wear accompanied by slight adhesive wear. The netlike silicon dioxide skeleton reduced the probability of abrasive wear, forming an integrated lubricating film.