Head Curvature of Pure Titanium Sheet Influenced by Process Parameters and Controlling in Hot Rolling Process

We investigated the influences of process parameters on the head curvature of pure titanium sheet in hot rolling process and proposed the controlling means. First, the thermal simulation experiments for pure titanium TA1 were carried out to investigate the hot deformation behaviors of pure titanium in the temperature range of 700-800 ℃ with strain rate range of 1-20 S-1, and the processing map was established to determine optimized deformation parameters. Then, the finite element model has been constructed and used to analyze the effect of process parameters on the direction and severity of head curvature of pure titanium sheet. The process parameters considered in the present study include workpiece temperature, work roll diameter, pass reduction, oxide scale thickness of workpiece surface, and interface friction coefficient. The simulation results show that the workpiece temperature and the interface friction coefficient are the two main factors. The proposed controlling means was carried out on a hot rolling production line and solved the head curvature problem effectively. The rolling practices indicate that the rolling yield is improved greatly.

Improvement and Experiment of the Reamer in Vibra Cutter Against Wave Edge of Titanium Sheet Alloy Parts

By analyzing the influencing factors of part quality making of sheet alloy of titanium by vibra cutter, the shape of upper reamer is set as cylinder and wedge-shaped form, and the lower reamer as plain and hemicycle form, and its main structural parameters are defined as well. Then it is validated further that such improved vibra cutter reamer can be used to process curve-edged parts of titanium alloy sheet. The experimental result shows that the titanium alloy sheet parts processed by above equipment have no sharpen angles for convex parts and evident crevasse of concave-edged part. In summary, such improvement can eliminate the free-waved edge and improve the manufacture quality of titanium alloy sheet parts greatly.

Effect of high density electropulsing treatment on formability of TC4 titanium alloy sheet

An annealed TC4 titanium alloy sheet was treated by high density electropulsing(Jmax=(5.09-5.26)×103A/mm2,tp=110μs)under ambient conditions.The effect of electropulsing treatment(EPT)on the plastic deformation behavior of TC4 titanium alloysheet was studied using uniaxial tension tests.The experimental results indicate that electropulsing treatment significantly changesthe mechanical properties of sheet metal:the uniform elongation is increased by 35%,the yield stress is decreased by 19.8%and theyield to tensile ratio is decreased by 17.6%.It is of significant meaning to improve the formability of TC4 titanium alloy sheet.Theoptical microscope and scanning electron microscope(SEM)were used to examine the changes of the microstructure and the fracturemorphology before and after the electropulsing treatment.It is found that recrystallization occurs in the sheet metal and dimples infracture surface are large and deep after the electropulsing treatment.The research results show that the electropulsing treatment is aneffective method to improve the formability of titanium alloy sheets.

Deformation behavior of TC1 titanium alloy sheet under double-sided pressure

In order to investigate the influence of normal stress through thickness on the formability of sheet metal,the viscous pressure bulge(VPB)tests of an annealed TC1 titanium alloy sheet were carried out under two different conditions:double-sided pressure bulging and conventional single-sided pressure bulging.The automated strain analysis,measurement environment(ASAME)and scanning electron microscope(SEM)were used to study the strain distributions and the fracture morphology of bulged specimens.It is found that thickness strain is increased for double-sided pressure bulging specimens,and the limiting dome height(LDH)of double-sided pressure bulging specimens is increased by 31.8% compared with conventional single-sided pressure bulging specimens.The dimples in fracture surface for double-sided pressure bulging specimens are larger and deeper than those for conventional single-sided pressure bulging specimens.The results indicate that normal stress through thickness is helpful in improving the formability of titanium alloy sheet metal.

Research on microstructure and property of electron beam welding joints of titanium alloy sheets

This paper reports research into the microstructures and properties of electron beam welding （EBW） joints of a Ti alloy sheet. To control the TC4 sheet joint formation during electron beam welding is not an easy task. However, the electron beam current has a significant influence on joint formation and a good appearance of a T-joint can be obtained by increasing the heat input and using the electron beam scan method. It was found that all acicular martensite in the fusion zone （FZ） consisted primarily of α＇ phase titanium, with some β phase present. Grain coarsening occurred in the heat-affected zone （HAZ） due to transformation of the β phase. Butt joints possessed high strength, hardness of the fusion zone, and the heataffected zone of these joints performed better than that of the parent metal. The highest shear strength of T-joint was 615 MPa and the fracture mechanism was a gliding fracture.

热处理温度对TA15钛合金板材组织及性能的影响

本研究对冷加工态TA15钛合金板材进行了750℃、800℃、850℃和900℃四种温度的热处理,并深入探讨了处理后的显微组织、室温拉伸性能、弯曲性能、洛氏硬度和高温性能。结果显示,在750℃时,板材的横向为等轴组织,纵向含有少量拉长组织;而在800℃至900℃范围内,板材的横向和纵向均形成了均匀细小的等轴组织。随着热处理温度从750℃升至850℃,板材的拉伸强度逐渐降低,而伸长率、弯曲角度则有所增加,洛氏硬度逐渐下降。值得注意的是,800℃至850℃热处理的板材显示出优异的综合性能,特别是850℃热处理的板材已完全再结晶。因此,建议TA15钛合金冷轧板材在这个温度范围内进行热处理,以获得最佳的显微结构和力学性能。

熔融制样-X射线荧光光谱法测定氯化炉渣中12种组分含量

本文采用钒钛高炉渣、钒渣、高钛渣、高炉渣等标准样品建立含量范围梯度大的标准曲线,同时测定氯化炉渣中Al、Si、Fe、Ca、Mg、P、Ti、Mn、K、Na、V、Cr。采用熔融制样,以四硼酸锂-偏硼酸锂混合熔剂(67∶33)作为熔样体系,讨论了熔融制样熔剂选择、熔片温度、稀释比及脱模剂用量等条件对熔片效果的影响。使用变化理论α系数校正,谱线重叠校正对标准曲线进行校正,对方法的精密度进行了考察,其中相对标准偏差为0.21%~4.20%(n=10)。分析结果与容量法和电感耦合等离子体原子发射光谱法分析结果进行对比,结果令人满意,本方法可适用于氯化炉渣样品成分的快速分析。

Effect of rolling and heat treatment on microstructure and properties of Ti-26 sheet

The effect of heat treatment and rolling process on the properties and microstructures of Ti-26(Ti-15V-3Al-3Cr-3Sn-Forming) sheet was studied. The results show that the best rolling temperature for Ti-26 alloy is in the temperature range from 900 ℃ to 950℃. Under this condition,the resistance of deformation and yield ratio are low and the alloy has better hot work ability. The alloy will achieve better mechanical properties and completely recrystallized β microstructure when the deformation ratio is not less than 60% and the solution temperature is 30 ℃ above the phase transformation temperature. The best heat treatment conditions are recommended as:790℃,30 min,AC or WQ followed by 510 ℃,10 h,AC. Under this heat treatment condition the strength of the Ti-26 alloy is 1 230 MPa and the elongation is 15%.

钛/铁复合板平底球形薄壁件充液拉深工艺研究

目的选用充液拉深先进成形技术制备钛/铁复合板平底球形薄壁件,并研究其充液拉深变形行为,以解决传统拉深工艺制备平底球形薄壁件极易产生褶皱的问题。方法对钛/铁复合板平底球形薄壁件在不同液压力、压边间隙及凸模与板料间摩擦因数等工艺参数下的充液拉深过程进行数值模拟。对数值模拟结果进行分析,讨论工艺参数对零件成形性能的影响以及抑制起皱的机理。最后在不同拉深工艺下进行成形试验,制备钛/铁复合板平底球形薄壁件并与数值模拟结果进行对比。结果数值模拟和成形试验结果表明,传统拉深工艺制备的钛/铁复合板平底球形薄壁件出现了明显的褶皱,采用充液拉深工艺可以有效解决零件侧壁起皱的问题。增大液压力、减小压边间隙或增大凸模与板料间摩擦因数会导致零件减薄率的提高并降低零件侧壁起皱的风险。在压边间隙1.5 mm、液压力25 MPa的条件下,采用充液拉深工艺可以制备出侧壁无褶皱的平底球形薄壁件。结论通过充液拉深工艺可以有效解决钛/铁复合板平底球形薄壁件成形过程中起皱的问题。

Numerical modeling and experimental study of microstamping process for fabricating microchannels using thin sheets of titanium

Ultra-thin sheets of titanium for fabricating microchannels have been used in fuel cells due to their good corrosion resistance and high strength-weight ratio. This paper presents a constitutive model for studying the anisotropy effects of pure titanium(CP-Ti) sheet on the springback behavior and forming properties during the microstamping process. Thin sheets of CP-Ti specimens with different orientations were examined using uniaxial tensile tests to assess the effects of anisotropy on their mechanical properties. Then an anisotropic constitutive model considering the off-axis elastic modulus was developed based on orthotropic elasticity and Hill's yield criterion. Numerical modeling and simulation of the microstamping process for fabricating multi-channel structures were performed. The effects of anisotropy on the springback of multi-channels were investigated and compared with experimental results;the effects of tool dimension parameters on the formability of microchannel structures were also analyzed. The results showed that the anisotropy of thin titanium sheets causes various degrees of forming loads and springback in the microstamping of microchannels at different orientations. This study accurately predicts the springback of thin titanium sheet used to fabricate microchannel structures and is a good guide to the formation of such structures.

热处理温度对TA7钛合金板材组织与力学性能的影响

研究了TA7钛合金板材热加工态和经750、800、850℃3种不同温度热处理后的显微组织、室温拉伸性能、弯曲性能、高温拉伸性能和高温持久性能。结果表明,热加工态TA7钛合金板材横向存在不均匀组织,纵向有较多拉长α晶粒;经750℃热处理后板材拉长α晶粒转变为等轴状;经800℃热处理后板材横向与纵向均为均匀、细小的等轴组织;经850℃热处理后板材晶粒发生长大。热处理后板材强度降低,塑性增加,弯曲性能和高温持久性能均满足GJB 2505A—2018标准要求;随着热处理温度的升高,板材室温拉伸强度和高温拉伸强度均逐渐降低,经850℃热处理后板材的500℃高温拉伸强度已不能满足要求。为了获得均匀、细小的组织及良好的力学性能,TA7钛合金板材宜采用800℃热处理。

α+β固溶处理对Ti65合金薄板的影响:硅化物析出、力学行为和新型{1011}孪晶系

为应对航空领域对轻质和优异高温性能钛合金部件的迫切需求,对经不同热处理的新型高温钛合金Ti65合金薄板的显微组织演变、硅化物析出和力学行为进行系统研究。结果表明:在固溶空冷后的合金中析出亚微米级硅化物(Ti,Zr)_(6)Si_(3),导致拉伸性能变差和剧烈波动。在950℃固溶炉冷后的合金中发现穿晶界(Ti,Zr)_(5)Si_(3)和近晶界(Ti,Zr)_(6)Si_(3)硅化物的共存。当固溶温度升高至1010℃时,(Ti,Zr)_(3)Si硅化物在位错附件出现。薄板固有尺寸效应与硅化物析出的协同效应导致拉伸性能的明显波动,塑性显著下降,甚至发生脆性断裂。硅化物析出受低温固溶处理的保温时间的影响较弱。此外,在990℃热轧获得的薄板中观察到新型{1011}孪晶,其轴角对为65°<8443>,仅存在于粗大的基面织构α晶粒中。

钛合金板材制备技术的现状及展望(上)——薄板制备技术

钛合金板材类产品在航空、航天、海洋、船舶等国防领域有着广泛的应用,其制备技术多年来不断突破、完善,但并未完全成熟。本文梳理了钛合金板材制备技术的概况,介绍了板材轧制成形的工艺方法,重点分析了钛合金薄板制备技术的现状及问题。通过梳理冷轧和包套叠轧两种制备钛合金薄板的工艺技术,对比了不同钛合金类型(α钛合金、α+β钛合金和β钛合金)的制备工艺和显微组织特征,阐明了钛合金薄板制备技术的关键控制要点,剖析了钛合金薄板产品的现存问题并提出了具体解决方案。最后,展望了国内钛合金薄板制备技术的研究重点和未来发展方向。

普陀山观音圣坛工程技术创新

文章介绍了国内首个“毗卢观音”造型为建筑形态的复杂宗教文旅建筑——普陀山观音圣坛的技术创新与技术突破,重点包括“须弥山”多曲面双层斜交空间网格清水混凝土结构、“如意塔”巨型复杂空间曲面劲性混凝土结构、“毗卢观音”复杂佛教建筑造型装饰等多项技术攻关,解决了大型复杂现代宗教文旅建筑工程施工难题。

二氧化钛催化剂成型技术研究进展

二氧化钛具有优良的化学性质,在催化剂领域应用广泛,然而单独的二氧化钛粉体成型困难,限制了其工业应用。本文归纳总结了二氧化钛催化剂的成型技术研究进展,包括挤条成型、压片成型、滚球成型和整体式成型。成型工艺可使二氧钛催化剂具有良好机械强度和催化性能,满足多数工业生产需要。

TB2钛合金电化学机械抛光试验研究

航天器用星箭连接带的材料为TB2钛合金,对表面质量要求严格。提出电化学–电化学机械组合抛光TB2钛合金的方法,通过机械作用控制表面TiCl4黏性层厚度,设计了固结磨料工具阴极,搭建了电化学机械抛光试验系统。开展了不同组合形式的电化学–电化学机械组合抛光优选试验,研究了电压、工具转速、进给速度等工艺参数对组合抛光后表面质量的影响,最后,在电压25 V、工具阴极转速100 r/min、工具阴极进给速度30 mm/min,电化学抛光1次+电化学机械抛光1次组合形式交替加工15次的条件下,获得了表面粗糙度Ra0.031μm、Sa0.082μm的表面。实现了TB2钛合金薄板零件的连续抛光。

基于双侧辅板约束的钛合金U形件室温下柔性自由渐进成形

为了实现低塑性钛合金板料在室温下的成形,提出了基于方向交替的扩张型加工轨迹,用于基于双侧辅板(DC05或SAPH440)约束的钛合金柔性自由渐进成形(FFISF)。利用ABAQUS对TC4钛合金U形件的室温FFISF过程进行了有限元分析,为工艺参数的选择提供指导。结果表明,所提出的加工轨迹可以有效提高上辅板的成形能力,避免了传统加工轨迹导致的上辅板中心隆起缺陷和侧壁褶皱缺陷,使其在加工过程中全程辅助TC4钛合金目标板材产生相应的塑性变形。将新型加工轨迹与合理的工艺参数应用于FFISF,可以在室温下成形出TC4钛合金直壁角U形件,成形件具有良好的几何精度、表面质量和均匀的厚度分布。分析表明,零件实际壁角大于加工轨迹壁角,原因在于成形过程中零件侧壁向中心夹紧并且在上、下辅板之间出现空腔。

蒸发速率对硅衬底电子束蒸发钛薄膜性能的影响

采用电子束蒸发法在硅衬底表面制备Ti薄膜。采用原子力显微镜、四探针电阻测试仪和应力测试仪分析了在不同蒸发速率下所得Ti薄膜的表面粗糙度、方块电阻和残余应力。结果表明,随着蒸发速率从0.1 nm/s升高到1.0 nm/s,Ti薄膜的表面粗糙度和方块电阻逐渐降低。不同蒸发速率下所得Ti薄膜的残余应力均为压应力,并且随蒸发速率的升高而增大。

Ti/CoWO_(4)光阳极的制备及其光电催化性能

采用一步水热法在钛基底上制备一种具有优秀半导体特性的Ti/CoWO_(4)光阳极,通过改变水热反应时间可调节附着在基底表面的CoWO_(4)纳米球的数量,其中Ti/CoWO_(4)-6 h具有更大的活性面积、更高的电荷转移能力及更高的中间活性物种(自由基)生成效率.通过紫外可见(UV-Vis)光谱和扫描电子显微镜(SEM)等方式对材料进行表征,考察Ti/CoWO_(4)光阳极对活性艳蓝(KN-R)的光电催化(PEC)降解活性.结果表明,在PEC条件下,Ti/CoWO_(4)-6 h对KN-R(60 mg/L)脱色率可达84.97%,5次循环后降解率仍能达到74.91%.

网状结构TiB_(w)/TA15复合材料热轧薄板的显微组织演变与力学性能

通过包套热轧方法,在1000和1100℃温度下热轧制备两张具有网状结构TiB_(w)/TA15钛基复合材料薄板。两张薄板的轧下率分别为86.7%(尺寸为932 mm×393 mm)和89.3%(尺寸为987 mm×461 mm)。两张热轧薄板的显微组织具有显著差异,薄板中的网状结构变成了具有扁平椭球单元的层状结构。相较于板坯,在1000和1100℃条件下热轧薄板的室温拉伸强度分别提高了26.4%(1398 MPa)和23.0%(1360 MPa)。在600℃拉伸试验中板坯和薄板的抗拉强度为561 MPa(板坯)、662 MPa(1000℃热轧薄板)和758 MPa(1100℃热轧薄板)。在650℃的拉伸试验中,1100℃热轧薄板的抗拉强度(553 MPa)最高。