Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： The surface micro-texture has the characteristic of changing the lubrication state of the frictionsurface , and has been applied in gear transmission. In this paper , the effect of groove shape micro-textureon gear lubrication is studied. First , the secondary development of micro-textured tooth surface gears isused to automatically generate ideal grooves. Then the micro-groove texture is simplified into two models,which can be imported into the Fluent module of ANSYS in order to analyze the different parameters of thegroove ( such as groove width , depth , angle , and spacing ). The numerical results show that as the width ofthe groove increases , the carrying capacity increases. 'The influence of the depth of micro grooves on thelubrication characteristics is non-linear , with an optimal value.Properly increasing the groove spacing andthe angle of the micro grooves can improve the fluidity and continuity of the lubricating oil , thereby impro-ving and maintaining the lubrication effect. This article lays a theoretical foundation for further applicationof micro-textured gears.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： Microstructure and texture of titanium alloy are determined by thermomechanical and heat treatments and can significantly affect the mechanical properties of the final products. In this work, the microstructure and texture evolution during the heat treatment in a /b and b phase field in Ti60 precision forging bars were investigated. The results implied that the actual deformation temperature gradually decreased during precision forging processes. The microstructure and texture of Ti60 bar were determined by the finish forging temperature and the diameter, and strong microtexture macrozones existed in the forged Ti60 bar. For the bar with diameter of 45 mm (D45), the finish forging temperature fell in the lower temperature region of the a /b phase field, and the main a textures in these bars were <0001> and <101ˉ0> fiber texture components in initial Ti60 bar. The similarity of the microstructure and texture were found after heat treatment at 950 ℃. The intensity of <101ˉ0> fiber texture gradually decreased while that of <0001> fiber texture increased with the increase of the heat treatment temperature. Heat treatments have little influence on the strength of forged Ti60 bars of D45, while their ductility was reduced after b heat treatment. For the bar with diameter of 30 mm (D30), the finish forging temperature was below the a /b phase field, and the main a texture in those bars was <101ˉ0> fiber texture component. The intensity of <0001> fiber texture in those bars increased while that of <101ˉ0> fiber texture gradually decreased with the increase of the heat treatment temperature. Their room temperature strength significantly increased with the increase of the heat treatment temperature, and yield strength and tensile strength reached to 1086 and 1144 MPa, respectively, but the elongation only 3.3% after b heat treatment.
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-04 Cooperative journals: 《金属学报》
Abstract：α/β两相区精锻的Φ30mm和Φ45mm Ti60棒材分别在950℃、1000℃、1050℃固溶+时效热处理，研究了棒材显微组织、织构及其对拉伸性能的影响。结果表明，Φ45mm棒材中存在较强的和平行于棒材轴向的丝织构；950℃热处理后显微组织和织构变化不明显；随固溶温度升高，晶体方向平行于棒材轴向的丝织构增强，而丝织构密度减弱；固溶温度对棒材强度的影响不大。Φ30mm棒材中主要存在方向平行于棒材轴向的丝织构，固溶温度升高，晶体方向与棒材轴向平行的织构逐渐增强，棒材的室温强度随固溶温度升高而显著升高。
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： To reduce the weight of car body, Al-Mg-Si-Cu alloys have been used to produce outer body panels of automobiles due to their relatively good formability in the solution treated condition and high strength in the age hardened condition. However, their formability is significantly poor compared to that of steels, which are the major drawbacks to wide-scale application of aluminum in the automotive industry. The microstructural characteristics developed during recrystallization, most notably grain size and crystallographic texture, play a dominant role in controlling the mechanical properties and formability of sheet in the T4 condition. In this work, the effect of particles with different sizes on the mechanical properties, microstructure and texture of Al-Mg-Si-Cu alloys was studied through tensile test, OM, SEM, TEM and EBSD measurement. The results reveal that with increase of solute concentration, the average plastic strain ratio rˉ, yield strength and ultimate tensile strength increase, but the elongation decreases and with different extents in the three directions. In addition, the number of observed particles with different sizes in the alloy matrix such as Mg2Si, Al15Mn3Si2 and a-Al(Fe, Mn)Si phases also increases. When the size and concentration of the se particles are controlled appropriately, lots of finer recrystallized grains can form during solution treatment due to the particle stimulated nucleation (PSN) effect of coarse particles and pinning effect of finer particles. The main texture components include CubeND18, Goss{011}<100>, P{011}<122> and Cu{112}<111> for the alloy with fine-grained structure. At last, according to the relationship among alloy composition, thermomechanical processing and microstructure, the model of nucleation and growth of recrystallized grains affected by the particles with different sizes was also proposed.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： Evolution of drawing texture for A6 aluminum conductor with the drawing process was investigated by macro and micro-texture analysis. The results show that the fiber-like deformation texture of <111> and <100> formed in the drawing process, and <100> texture reduced while <111> texture enhanced with the increasing strain. The distribution of deformed texture was of homogeneity along the radial direction of wire: the deform texture transformed from strong <100> texture (~52% volume fraction) in the surface to strong <111> texture (~55%) in the center by moderate strains; the radial gradient texture was weakened and a strong <111> texture (>70%) formed in the overall wire by high strains. Moreover, the core hardness of the wire was higher than that of the surface, which attributed to the texture gradient distribution along the radial. Adjusting the drawing process to optimize the dislocation density and texture as well as their distribution in the wire is an effective route to improve the strength and conductive properties of the A6 aluminum conductor.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： The phase change materials of fatty acid/SiO2 composite were prepared by sol-gel method with SiO2 as carrier material, fatty acid as phase change material, absolute alcohol and deionized water as solvent, Which then were characterized by scanning electron microscope (SEM), laser particle size analyzer (LPSA), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC) etc. The effect of the type of cores, the amount of phase change material and absolute alcohol and deionized water as well as the solution pH value and ultrasonic wave power on the texture of the prepared composites were investigated systematically. The results show that the texture of the phase change materials of fatty acid/SiO2 composite was greatly influenced by the type of cores, the amount of phase change material and absolute alcohol and deionized water, and also related to solution pH value and ultrasonic wave power. The optimal processing parameters for preparation a good composite are: decanoic acid-palmitic acid acts as core, the mole ratio of decanoic acid-palmitic acid to tetraethyl orthosilicate is 0.4, the mole ratio of absolute alcohol to tetraethyl orthosilicate is 5, the mole ratio of deionized water to tetraethyl orthosilicate is 9, solution pH value is 4 and ultrasonic wave power is 200 W.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： Cu thin films were deposited by magnetron sputtering on SiO2 substrate pre-coated without and with a thin Ti seed layer. Then the surface morphology and micro-texture of the films were characterized by means of electron back-scattered diffraction (EBSD) and atomic force microscope (AFM). The results show that the Cu thin film deposited on the Ti seed layer showed a highly oriented {111} fiber texture. Meanwhile, the generation probability of twins of the Cu thin films induced by annealing treatment could be decreased due to the existence of the Ti seed layer, but voids could occur on the Cu thin film.
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-15 Cooperative journals: 《金属学报》
Abstract：本文取初始织构为c轴与板面法向垂直的强织构AZ31镁合金板材为初始样品，经液氮温度深低温轧制多道次至不同变形量，研究所得的轧制板材的显微组织与织构演变，及其对轧制力学性能的影响。本研究利用SEM、EBSD和X射线衍射表征分析了轧制板材的显微组织和织构，重点研究了板材深低温轧制过程中的孪生变形，以及孪晶组织对板材微观组织与织构的影响，并应用准静态单轴拉伸实验分别测试了深低温轧制板材沿轧向（RD）和横向（TD）的室温力学性能，讨论研究了板材的力学性能与显微组织和织构之间的联系。研究表明，当板材织构有利于拉伸孪生时，{10-12}拉伸孪晶在深低温轧制过程中十分活跃，深低温轧制过程中活跃的孪生行为对于镁合金的显微组织、织构及力学性能都有着重要的影响。
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： To find out the reason of poor secondary recrystallization behavior in thin-gauged grain-oriented steel, EBSD technique is applied to reveal the grain growth behavior of thin-gauged steel processed by HiB steel method under high cold-rolling reduction. Nitriding treatment with different times is conducted to ensure the occurrence of secondary recrystallization in thin-gauged grain-oriented steel and to determine the effect of nitrogen content. Attention is put on the influence of {114}<418> texture on the abnormal growth of Brass and Goss grains. Results show that, at initial stage of secondary recrystallization, {114}<418> grains in the surface region of sheets possess obvious growth advantage than the other oriented grains. If these grains in the surface region grew to the central layer of sheet and swallowed the nucleus of secondary recrystallization, abnormal growth could not occur. In contrast, reinforcing the inhibitors at surface region of sheet by nitriding treatment will avoid the excessive growth of surface grains and therefore improve magnetic properties of steel significantly. The {114}<418> grains are adverse to the abnormal growth of Brass-oriented and scattered Goss grains in way of island grains, but their effect on the abnormal growth of Goss grains is weaker.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： Precipitation behavior of second phase in two micro-carbon steels with different amounts of Nb and Ti were investigated using SEM and TEM technique. In the meanwhile, the effect of precipitates on microstructure, texture evolution and properties of the micro-carbon steels was investigated by XRD and EBSD technique. Results show that precipitates in the micro-carbon steels were mainly consisted of larger size (Nb, Ti)(C, N) composite particles and finer Nb-based carbide and carbonitride dispersed in matrix. With the increasing of Nb and Ti addition the fine second phase particles increased significantly, which strongly inhibit the development of <111>//ND fiber texture during recrystallization, especially for {223}<110> and {111}<110> orientation. As for micro-carbon steel with low content of Nb and Ti, a good combination between strength and deep drawing ability can be acquired due to the occurrence of a matrix of polygonal ferrite and martensite transformation during fast cooling process.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《材料研究学报》
Abstract： The friction and wear properties of graphene (GP) as a lubricant additives were investigated by means of a UTM-2 tribometer via a ball on plate contact reciprocating sliding. The molecular structure and morphology of graphene nano sheets were characterized by TEM, SEM, XRD, IR and Raman spectroscopy. The friction and wear test was performed with lubricant of PAO4 oil without and with addition of 0.01% graphene (GP) respectively at different temperatures for the textured bronze with different ratio of textured area. The results show that GP can effectively reduce the friction and wear, especially at 60℃ and 100℃. For the simple PAO4 oil, the bronze with untextured surface exhibits the lowest friction coefficient and wear rate at 60℃ and 100℃; whilst, with the increasing ratio of the textured area, the friction coefficient and wear rate increase. For graphene-containing PAO4 lubricating oil, the friction coefficient is lower for the bronze with 5% textured area, while higher for those with 20%; the wear rate is lower for the bronze with 10% textured area.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《材料研究学报》
Abstract： The characteristics for the evolution of grain orientation and texture of ring shaped blanks of sand- and centrifugal-casting Q235B respectively were investigated by electron backscatter diffraction (EBSD) technique, while the blanks have been subjected to hot compression with a strain rate of 0.1 s-1 at different temperatures. The results show that the grain size of the blanks after hot compression at 1000℃ becomes smaller in the deformed microstructure, but a few grains maintains as in cast state. The mechanisms of the microstructure evolution may be ascribed to dynamic recovery and large strain geometric dynamic recrystallization. For centrifugal cast ones, the percentage of high- angle boundary in 20°- 50° is 22%, but after hot compression at 1100℃ it shows a homogenous microstructure with equiaxed grains because of sufficient recrystallization, while the mis-orientation distribution of grain boundaries still presents a typical characteristic of double- peaks and the proportion of the high- angle boundaries reaches to 60%- 75%. The textures of sand casting Q235B are a small amount cube texture {001}<100> and {001}<110> along <001>//ND at 1000℃ , while the main textures are Goss texture {110} <001> and r- cube texture {110}<001> at 1100℃. For centrifugal casting ones at 1000℃, {110}<110> and Cu texture {112}<111> dis-tributes along ε orientation; at 1100℃ the types of texture including {001}<110> and {111}<110> transformed from {111}<112>alongg orientation.Theorientation density is higherdueto the high extent of recrystallization.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： Different numbers of columnar grains in a Fe-3%Si electrical steel slabs with their major axes being parallel to the rolling direction were used for cold rolling and recrystallization annealing. The evolution of the texture of columnar grains was followed by EBSD technique. The results show that, in the case of single columnar grain with cube orientation, cube texture is adverse to be retained in condition of primary cold rolling with high reduction and recrystallization annealing, while strong cube texture can form after secondary cold rolling with low reduction and recrystallization annealing. But the cube texture hinders strongly the abnormal growth of Goss grains. For the sample containing two columnar grains with Goss and cube orientation, the initial Goss orientation rotates to {111}<112> orientation quickly and cube texture is retained effectively during cold rolling by high reduction. The interaction between the Goss and cube columnar grains is not strong. For the multi-columnar grains with different orientations, the grain boundaries between columnar grains promote g- texture and weaken the cube texture, which is in favor of abnormal growth of Goss grains.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： Twinning induced plasticity (TWIP) steel exhibits high strength and exceptional plasticity due to the formation of extensive twin under mechanical load and its ultimate tensile strength and elongation to failure ductility-value can be as high as 5�104 MPa�%, which provide a new choice for automobile in developing the lightweight and improving safety. Generally, due to the texture was formed during process of plastic deformation, metal material appear anisotropic behavior. The deformation mechanisms, responsible for this high strain hardening, are related to the strain-induced microstructural changes, which was dominated by slip and twinning. Different deformation mechanisms, which can be activated at different stages of deformation, will strongly influence the stress strain response and the evolution of the microstructure. In this work, to predict the texture evolution under different loading conditions and understand these two deformation mechanisms of plastic deformation process, a polycrystal plasticity constitutive model of TWIP steel coupling slip and twinning was developed based on the crystal plasticity theory and single crystal plasticity constitutive model. A polycrystal homogenization method to keep geometry coordination and stress balance adjacent grains was used, which connected the state variables of single crystal and polycrystal. And then the model was implemented and programed based on the ABAQUS/UMAT platform. The texture evolution was obtained by EBSD at strain 0.27 and 0.60, respectively. The finite element models of tensile, compression and torsion processes were built by using the constitutive model. The mechanical response and texture evolution during plastic deformation process of TWIP steel were analyzed. The results show that with the increasing of the strain, the strain hardening phenomenon and texture density enhanced during the tensile process. Although texture types changed, texture density unchanged during the compression process. Owing to deformation increasing along the diameter direction, there is no obvious texture inside the cylinder when torsion deformation is small, texture emerged and enhanced gradually with the increasing of strain.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： Plasma arc cold hearth melting (PAM) is an effective technology to produce high purity titanium alloy ingots which are widely used in aeronautic and astronautic industries. To date, the development of PAM in our country is still at initial stage. It is necessary to investigate the melting parameters of PAM and the following thermal mechanical processing of the ingots fabricated by PAM. In this study, the TC1 alloy ingots casted by PAM were cogged at b transus temperature and then rolled by unidirectional rolling and cross rolling in the a+b phase field. The typical widmanstatten structure of cast- ingots turned to transformed b morphology after cogging at b transus temperature in which the a phases forms in smaller colonies of laths. After the unidirectinal rolling in the a+b phase field, the a colonies were distorted and the a laths re-arranged along the rolling direction, while they had weaker directivity after cross rolling. The sheets rolled by both unidirectional and cross rolling showed typical prismatic texture. After annealing treatment below the b transus temperature, the a phases turned to equiaxial morphology. The ambient yield strength of the sheet in transverse direction was significantly higher than in rolling direction, which could be attributed to the strong prismatic texture introduced by hot rolling process.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： A nickel-based (Ni0) composite coating, which was reinforced with 20%WC and 6% graphite particles and has a texture-like section morphology, was fabricated on steel substrate by vacuum cladding technology. Then its microstructure and tribological property under dry friction condition were characterized in comparison with other three coatings (Ni0, Ni0+20%WC and Ni0+6% graphite). The results show that the WC particles evenly distributed in the nickel-based (Ni0) alloy coatings and formed a special 3D reticular microstructure. The Ni-based alloy coating is mainly composed of γ-Ni solid solution, hard phases (Cr7C3, Cr23C6, CrB) and eutectic phases (Ni3Si, Ni3B). The cladd composite coating consisted of Ni0 with WC and graphite particles exhibits the highest wear resistance among the test coatings. The combination of texture-like structure (which was composed of WC particles and nickel base alloy) and graphite lubricant promoted the abrasion resistance of the composite coating by about 9.6 times in comparison to the pure Ni0 coating.
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-04 Cooperative journals: 《金属学报》
Abstract：等离子冷床炉由于其熔炼铸锭的高纯净度而广泛应用于航空航天钛合金的熔炼。我国工业化等离子冷床炉熔炼钛合金尚处于起步阶段，其熔炼参数及其熔炼铸锭的后续热加工工艺急待研究。本研究以工业化等离子冷床炉熔炼的TC1钛合金为研究对象，结合实际生产流程，并借助于中子衍射技术，研究不同轧制工艺对TC1轧制板材显微组织与性能演变的影响，揭示组织结构与力学性能之间的关系。研究结果表明，冷床炉熔炼的铸锭组织为魏氏组织。经过轧制后，α集束发生扭曲和破碎。单向轧制变形α相沿轧向排列较换向轧制更为明显。退火后，板材中变形α相发生等轴化。经过单向轧制和换向轧制后，轧制板材均表现为柱面织构类型，这是板材横向屈服强度均明显高于其轧向屈服强度的主要原因。
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： To reduce the weight of car body, Al-Mg-Si-Cu alloys are becoming increasingly attractive as a candidate for material substitution used to produce the outer body panels of automobiles because of their favorable bake-hardening response. However, the formability still needs to be further improved compared to steels. In this work, the effect of the thermomechanical processing on the mechanical properties and microstructure of Al-Mg-Si-Cu alloy is studied through tensile test, OM, SEM and TEM observation, as well as EBSD characterization. The results reveal that there is almost no change in both strengths and strain-hardening exponent n of the sheets in T4P condition after different thermomechanical processing, but the average plasticity strain ratio r, planar anisotropy Δr and elongations in the three directions show obvious differences. The sheet undergone hot rolling, cold rolling, intermediate annealing, cold rolling and solution (processing II) has a better formability (r= 0.6187) and a weaker planar anisotropy than that subjected to hot rolling, intermediate annealing and then cold rolling before solution treatment (processing I). Although the particle stimulated nucleation (PSN) effect of processing I is remarkable during solution treatment, due to the appropriate controlling cold deformation and distribution of second-phase particles with different sizes in processing II, most of the recrystallization grains are equiaxial and the recrystallization texture is only consisted of CubeND, Cube and H with a low intensity. At last, according to the relationship between the microstructure and the thermomechanical processing, the microstructure evolution model during different thermomechanical processes is established.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： Si3N4 ceramics with preferential texture along a or b axis were shaped up by gel-casting in a magnetic field of 6T and then pressureless sintered. Effect of the sintering temperature and time on the texture formation of the Si3N4 ceramics was investigated. It was found that the phase transformation of α to β was completed for the Si3N4 ceramics prepared by the present process. With the increasing sintering temperature the texture formation of Si3N4 ceramics may be enhanced, i.e. of which the degree of texture increased from 0.40 at 1700℃ to 0.76 at 1800℃. The extension of sintering time at 1750℃ had few effect on texture development of Si3N4 ceramics.
Subjects: Materials Science >> Materials Science (General) submitted time 2017-04-10 Cooperative journals: 《材料研究学报》
Abstract：通过真空熔覆技术在 ZG45 表面制备了 Ni-Co/WC+G 复合熔覆层，观察并分析了复合熔覆层的显微组织 形貌和物相组成，通过摩擦磨损试验研究了石墨含量对复合熔覆层摩擦磨损性能的影响。结果表明，呈三维 网状织构形貌的复合熔覆层材料内部由于石墨的加入形成许多细小的“石墨孔洞”，这些“石墨孔洞”在摩擦过 程中可以作为贮存的润滑介质，增强复合材料的摩擦学性能。随着石墨含量的增加复合熔覆层的摩擦系数、 磨损率和 GCr15 钢对磨盘的磨损量逐渐降低，石墨含量为 6%时最小; 石墨含量为 8%时，对磨盘的磨损量又突 然上升，增幅达 70%。
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