ZHANG Li-li, ZHANG Xiao-yong, GAO Hui-lin, WANG Feng. Microstructure and Mechanical Properties of a High Nb-microalloyed X80 Pipeline Steel[J]. Journal of Materials Engineering, 2009, 0(5): 1-5.
Mechanical property testing and microscope analysis were applied to evaluate the microstructure and mechanical properties of a high niobium-microalloyed X80 pipeline steel.The results show that the high niobium-microalloyed pipeline steel possesses higher strength-toughness and lower ductile-brittle transition temperature,and was already successfully applied to the Second West-east Gas Pipeline Project in China.The effects of niobium-microalloyed element on grain refinement,microstructure strengthening and precipitation hardening of pipeline steel were analyzed.
ZHANG Lei, HU Li-hua, SUN Jian-bo, CHANG Wei, ZHANG Zhong-hua, LU Min-xu. Microstructure and Properties of CO2 Corrosion Resistant Low Cr Pipeline Steels[J]. Journal of Materials Engineering, 2009, 0(5): 6-10.
1%-5%(mass fraction)Cr addition to pipeline steels can enhance their CO2 corrosion resistance.The effects of Cr content on the microstructure,mechanical properties,corrosion and welding characteristics were investigated for the low Cr pipeline steels.The results showed that 3%-5% Cr addition changed the microstructure of the steels from ferrite and pearlite into bainite.By adding more than 1% Cr,the hardness and strength of the steels were obviously improved combined with good toughness.With Cr content increasing to 3%-5%,CO2 general corrosion rate of the steels was reduced and localized corrosion was inhibited because of the protective corrosion scale with Cr element enrichment.Good mechanical properties could also achieve on the weld joints of the Cr containing steels.However,the hardness of heat-affected zone(HAZ)increased too much when Cr content reaching 5%.
XU Wei-ping, WANG Yun, HU Yong, ZHOU Lang. Crystallographic Features Study of Polycrystalline Silicon Ingot for Solar Cells[J]. Journal of Materials Engineering, 2009, 0(5): 11-13.
The grain boundary character in polycrystalline silicon ingot was studied by electron back scattered diffraction(EBSD).The results showed that there was nearly no misorientation in a crystal.The misorientation was mainly in grain boundaries of polycrystalline silicon ingot.Most grain boundaries were observed with large angle grain boundaries.Σ3 was the chief of these large angle grain boundaries.Small angle grain boundaries were also observed with a low ratio.Low efficiency solar cells by polycrystalline silicon ingot might be related to high ratio of Σ3.
RAO Yang, ZHENG Liang, LIU Xiao-gong, XIAO Cheng-bo. Effects of Carbon Content on Microstructure and Tensile Properties of Alloy CoCrMo[J]. Journal of Materials Engineering, 2009, 0(5): 14-16,21.
The effect of carbon content on microstructure and tensile properties at room temperature of alloy CoCrMo was investigated.The results show that the second phases of alloy CoCrMo are carbides with high chromium,the volume fraction of the carbides increased with the carbon content.Within certain carbon content,the tensile properties of alloy CoCrMo can be improved by increasing the volume fraction of the carbides.According to the results of optical metallography(OM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),quantitative metallography of carbides and tensile tests in alloy CoCrMo with different carbon content,the best properties can be achieved by the content of 0.26%-0.30%(mass fraction)carbon.
CHENG Jiang-bo, LIANG Xiu-bing, XU Bin-shi, WU Yi-xiong. Microstructure and Wear Properties of Fe-based Amorphous/Nanocrystalline Coatings[J]. Journal of Materials Engineering, 2009, 0(5): 17-21.
FeCrBSiMnNbY amorphous/nanocrystalline coatings were fabricated on 45 steel substrates by high velocity arc spraying process.The microstructure of the coating was characterized using transmission electron microscopy(TEM),X-ray diffraction(XRD)and scanning electron microscopy(SEM)equipped with energy dispersive X-ray analysis(EDXA).The formation mechanism of amorphous/nanocrystalline was discussed.The wear behavior of the coating and the substrate was evaluated with wet sand rubber wheel abrasion tester at ambient temperature.The results show that the microstructure of the coating consists of amorphous and α(Fe,Cr)nanocrystalline.The nanocrystalline grains with a size of 30-60nm are homogenously dispersed in the amorphous matrix.The coating is fully dense with low porosity of 1.7%.The amorphous/nanocrystalline coating has high hardness and excellent wear resistance.The mainly failure mechanism of the coatings is brittle breaking and fracture mechanism.
GONG Jian-xun, LI Huang, XIAO Yi-feng, ZHANG Qing-hui. Microstructure and Wear Resistance of Fe-C-Cr-V-B High-chromium Hardfacing Alloys[J]. Journal of Materials Engineering, 2009, 0(5): 22-25,29.
High-chromium hardfacing alloys containing 1.2%-1.8%C,15%-20%Cr,2.0%-3.0%V and 0%-1.0%B(mass fraction)were deposited by the method of flux-cored wire submerged arc welding.The microstructure and carbide morphology were investigated by optical microscopy(OP),scanning electron microscopy(SEM)and X-ray diffraction(XRD).The results show that the microstructure consists of α-Fe,γ-Fe,carbide such as(Fe,Cr)7C3,(Fe,Cr)3C and boride such as Fe3(C,B),B4C etc.The addition of B4C powders results in grain refinement and Cr,V content in the solid solution matrix decreased,which made the volume fraction of(Fe,Cr)7C3 increase.The effects of B4C in flux-core wire on hardness and wear resistance were evaluated and the experimental results demonstrated that its relative coefficient was 6-17 times of solid wire H25Cr3Mo2MnV.Dispersed carbide which was surrounded by α-Fe matrix can suffer stronger attacking of abrasive particles without pulling off.
BI Xiao-qin, YANG Zhong-lei, HU Xiao-li. Microstructure and Performance of Ni-Cr Cladding Formed by Plasma Surfacing Processes[J]. Journal of Materials Engineering, 2009, 0(5): 26-29.
The cladding of Ni-Cr alloy was coated on the surface of 40Cr alloy steel by the PTA(Plasma Transferred Arc)surfacing process.The microstructures,component and microhardness of the coating were investigated.The results show that the coating obtained is well bonded to the matrix and the interface between the cladding and the matrix consists of the isometric crystal.The microstructure varies from relatively regular dentritic crystal in the middle of the coating to fine crystal near the top of the coating.The content of Ni and Cr change markedly on the interface by the spectrum analysis,shows that the cladding has low ratio of dilution.The hardness is the largest on the surface of the cladding and is reduced sequentially to the matrix,which changes observably on the interface.
ZHANG Ying-huai, XU Li-ning, LU Min-xu. Influence of Silane Treatment on Mechanical Performance of Organic Coating/Metal Adhesive Joint[J]. Journal of Materials Engineering, 2009, 0(5): 30-33,37.
The mechanical performance of the adhesive joint by silane treatment was investigated,and the influence of surface treatment on the mechanical performance of adhesive/metal interface was analyzed.The silane treated carbon steel was adhered by epoxy resin.Fatigue load was applied on the joint and then shear tension was applied.The change of stress-strain curves and the joint failure model was analyzed.The results show that the silane treated joint adhesive intensity improves after some cycles of fatigue,though the joint failure model is interface failure,the failure style is ductile fracture.The joint failure by shear tension is the mixture failure of interface and cohesive.
DI Xin-jie, LI Wu-shen. Box Dimension Changes Law of Metal Magnetic Memory Signal Under Tensile Load[J]. Journal of Materials Engineering, 2009, 0(5): 34-37.
The API 5L X70 pipeline steel was tested to finding the relation of the tensile load and feature signal of metal magnetic memory(MMM).The fractal theory was used to analyze the character of MMM signal that was proved as one of abnormity fractal signal.The conclusion is that with the loading increase,the box dimension of MMM feature signal decrease was obtained after the box dimension of MMM feature signal at different tensile load level was investigated.An effective method was provided for the technology of stress state evaluation with metal magnetic memory.
LI Xin-mei, ZOU Yong, ZHANG Zhong-wen, ZOU Zeng-da. Microstructure and Property of Novel Heat-resistance Steel Super304H After Being Aged at High Temperature[J]. Journal of Materials Engineering, 2009, 0(5): 38-42.
The microstructure and property of novel austenitic heat-resistance steel Super304H after being aged at 750-1350℃ were investigated by the means of optical microscope,scanning electron microscopy(SEM),X-ray diffraction(XRD),as well as hardness testing and impact test.The experimental results indicated that the microstructure of super304H after being aged included γ-phase and precipitated phase.With the variation of aging temperature,the grain size of matrix and the type of precipitated phase will be changed.When the sample was aged at 750℃,the hardness reached the maximum value due to the precipitation strengthening and fine microstructure.With increasing the aging temperature beyond 750℃,the microhardness rapidly decreased at first and then decreased slowly because of the variation of precipitated phase,grain size and solid solution elements.The impact energy value of aged sample increased before being aged at 850℃,and reached minimum when aged at 850℃ due to M23C6 precipitated along grain boundary and caused embrittlement.The impact energy increased again with increasing aging temperature,because the precipitated phase redissolved and eliminating the grain boundary embrittlement.
CHEN Hui-qin, CAO Chun-xiao, GUO Ling, LIN Hai. Dynamic Recrystallization Processes During Hot Deformation of TC11 Titanium Alloy in β Field[J]. Journal of Materials Engineering, 2009, 0(5): 43-48.
The hot deformation behavior and microstructure evolution of TC11 alloy with equiaxed starting structure were studied in 1030-1090℃ and strain rate range 0.001-0.1s-1 by hot compression tests.Characteristics of stress strain curves of the alloy deformed with the test parameters were analyzed.Kinetics analyses indicate that the stress exponent and deforming activation energy in β region are 4.05 and 172.3kJ·mol-1 respectively,which indicate that deformation would be dislocation slipping and climbing processes.Microstructure observation and EBSD testing indicate that discontinuous dynamic recrystallization occurred during hot deformation processes.Recrystallized grain size is a function of Z,a temperature compensated strain rate parameter.Based on dynamic recrystallization structure features at steady state,the modified Avrami kinetic model by prior grain size was established.By comparison,the results calculated by the model are identical to that of tests.
ZENG Guo-xun, ZHANG Hai-yan, GE Ying, CHEN Tian-li. Attenuation of Double-layer Type Microwave Absorber Made of Carbon Nanotubes-dielectric Composite Material[J]. Journal of Materials Engineering, 2009, 0(5): 49-52,56.
Electromagnetic parameters(EMP)of carbon nanotubes(CNTs)were measured at the range C1 band,which had two different diameters of 10-20nm and 40-60nm,respectively.The results show that CNTs composites have high dielectric loss.The single-layer CNTs coating has narrow width of Absorbing characteristic at S,C1 band.The results indicate that the double-layer type Absorber may improve the Absorbing property of the CNTs composites at C1 band,which made of surface layer of CNTs coating,bottom layer of dielectric composites with low dielectric constant,high intrinsic impedance.
FENG Kang-tun, SHA Ai-xue, WANG Qing-ru. Effects of Microstructure on Low Cycle Fatigue Property of TC18 Titanium Alloy Under Stress-controlled Condition[J]. Journal of Materials Engineering, 2009, 0(5): 53-56.
The effect of lamellar and bi-modal microstructures on low cycle fatigue life under different stress swing of TC18 titanium alloy was studied.The results show that fatigue life is not sensitive to the change of microstructure of TC18 titanium alloy.Fatigue lives of bi-modal and lamellar microstructures are very similar under the same stress swing.The low cycle fatigue life N of TC18 titanium alloy is determined by stress swing.The relationship between σmax and N is logarithmic and the correlative coefficient is larger than 0.99.
HU Chun-yan, LIU De-lin, WAN Fang, TAO Chun-hu. Fracture Analysis of Spline Shaft[J]. Journal of Materials Engineering, 2009, 0(5): 57-59,64.
The fracture reason of the spline shaft was analyzed by fracture observation,chemical composition analysis,metallurgical structure observation,hardness test and tensile test.The result shows that the fracture mode is fatigue fracture.The fracture is mainly caused by the lower hardness and strength which resulted from the Widmanstatten structure existing in the structure of the spline shaft.
WU Chao-bo, JIA Meng-qiu, GAO Da-hai, LI Wei. Effect of 60Co γ Ray Irradiation on Structure and Properties of Silicone Resins[J]. Journal of Materials Engineering, 2009, 0(5): 60-64.
At the room temperature,the effect of 60Coγ ray irradiation on the structure and properties of silicone resins was investigated in the atmosphere of air.The unirradiated,irradiated silicone resin and its clear paints were analyzed by FT-IR,TG,SEM,EIS etc.The FT-IR and TG analysis indicated that 60Coγ ray irradiation induced the rupture of side groups and cross-linking effect on silicone resins within the irradiation dose of 1.6×105Gy,resulting in an increase in their heat resistance.The surface morphology,mechanical properties,corrosion resistance and chemical resistance were not damaged under irradiation,proving that the synthesized silicone resins have good irradiation resistance.
LIU Pei-sheng, CHEN Yi-ming, DING Xiao-ji. Analysis of Porous Open-cell Metal Foams Under Bending Moment[J]. Journal of Materials Engineering, 2009, 0(5): 65-67.
Based on the performances of uniaxial tension and compression for porous metal foams,the mechanical behavior of these materials under bending moment was further investigated.The result shows that,the applied nominal bending moment can be expressed as a function of the porosity for the foamed metals under bending moment while the porous body endures the fracture,and this mathematical-physical relationship may be regarded as the extension of the expression about the relationship between the maximal nominal stress and the porosity for these materials under uniaxial tensile and compressive loads.
ZHANG Tao, ZHAO Bei-jun, ZHU Shi-fu, LI Kai, YONG Zhi-hua. Numerical Simulation Study of PBX Powder-forming[J]. Journal of Materials Engineering, 2009, 0(5): 68-72.
The warm compaction process of PBX(Polymer Bonded Explosive)powder was simulated with MSC.Marc FEM analysis software.The thermal-mechanical coupled analysis method based on the updated Lagrange Procedure was applied to simulate this process.The correlative data,including geometrical deformation,stress field and relative density distribution of PBX powder,were obtained.The results show that with increase of forming pressure,internal stress,powder displacement and relative density increase,and they have the same order of magnitude as the measured value.Warm compaction technology parameters can be improved and optimized according to the rule of the powder flowing property.
LIU Bin. Application of Liquid Penetrant Inspection of Surface Defects on Metallic Joint Components[J]. Journal of Materials Engineering, 2009, 0(5): 73-75.
Defects on component surfaces of artificial joint prostheses,manufacture flow and requirements of inspection were analyzed.Hydrophilicity post-emulsify penetrant inspection was selected as the method used for surface defect inspection of artificial joint prostheses and inspection time was selected.The results using femoral head as an example and analysis of other components indicate that liquid penetrant inspection is suitable for inspection of surface discontinuity larger than micrometer order.
LEI Li-ming, HUANG Xu, DUAN Rui, CAO Chun-xiao. Progress in Equal Channel Angular Extrusion Process[J]. Journal of Materials Engineering, 2009, 0(5): 76-80.
This paper presented an overview of principles and influencing factors of equal channel angular extrusion(ECAE).The latest progress in the die designs and engineering applications related to ECAE was introduced.In addition,the existing problems and future development direction of ECAE process are also proposed.
