Ta5W合金板材高质化加工工艺研究

用电子束二次熔炼得到Ta5W合金铸锭,研究了Ta5W合金的锻造和热处理工艺。结果表明,采用"十字交叉镦拔"锻造工艺和大加工率"换向开坯"开坯轧制工艺,能更充分破碎Ta5W合金铸态组织,采用1 400℃×60 min热处理工艺,能使材料最终获得均匀、细小的等轴晶组织,晶粒度达到6.5级以上。     

锻造对30CrNi2MoV钢在亚温淬火下组织与性能的影响

30CrNi2MoV钢是一种中碳合金钢,常用于制造高强韧性的大型锻件,广泛用于制造火电、核电等电站装备和大型冶金、矿山和运输装备中的承力和传动结构部件.为提高30CrNi2MoV钢的低温冲击韧性和室温强度,本文采用金相显微镜、扫描电子显微镜、拉伸机和硬度仪等方法对其进行组织观测、断口形貌分析和力学性能测试,研究了不同锻造方式对30CrNi2MoV钢的组织与力学性能的影响.结果表明:经过2次镦粗的30CrNi2MoV钢再经1次镦粗或1次镦粗+1次拔长两种锻造方式后能够有效细化且均匀晶粒,提高晶粒等轴性;与2次镦拔工艺的30CrNi2MoV钢相比,再经过1次镦粗或1次镦粗+1次拔长后其抗拉强度、延伸率和冲击韧性分别由1 043.6 MPa、35.65%和40.33 J提高至1 161.6和1 157.4 MPa、37.80%和36.13%、103和87 J.数据表明,30CrNi2MoV钢经过2次镦拔+1次镦粗工艺后,其组织与力学性能达到最好状态.     

液钽电容器外壳用深冲EB钽带加工工艺研究

本文通过对锻造、轧制及热处理工艺的研究,测试了材料的力学性能、晶粒度及金相组织,确定最佳工艺为轴向镦粗径向拔长＋三向循环镦粗拔长的锻造工艺,换向轧制的开坯轧制工艺,950℃×90 min的热处理工艺,该工艺制备的材料符合性能要求。     

TC4钛合金板不同加工条件下组织对比研究

通过对Ti-6Al-4V钛合金进行常规锻造及换向墩拔锻造热塑性变形加工,然后再进行多火次换向热轧变形,研究换向墩拔锻造热塑性变形加工及多火次换向热轧变形过程中Ti-6Al-4V钛合金组织的演变。试验结果表明,采用墩拔锻造与多火次轧制加工方式,板坯组织由原始双态组织(等轴α及转变(α+β))逐步演变成完全等轴α组织形态,组织更加细小、均匀,有效保证了板材组织及性能各向同性。     

热交换器用Ta40Nb合金管材加工工艺研究

Ta40Nb合金管材主要应用于化工防腐行业热交换器的加工。热交换器用Ta40Nb合金管材要求内部晶粒尺寸满足要求的同时还需满足其后续加工对材料力学性能的要求。本文通过对挤压、轧制、热处理等关键工艺的研究,确定了热交换器用Ta40Nb合金管材加工工艺。     

TC8合金转子叶片锻造工艺研究

为研制一项TC8合金转子叶片,并达到提高锻造生产效率、降低生产成本的目的,进行了锻造工艺性试验、工艺参数试验,研究了TC8合金锻造工艺适应性以及加热温度、变形程度对低倍组织、显微组织及力学性能的影响.结果表明,TC8合金十分适合锻造工艺,采用较低的锻造加热温度能够获得初生α相含量更高的等轴组织,变形程度在40%以内所获得的组织均匀性较好.在此基础上,依据TC8合金转子叶片单榫头、小尺寸的结构特点,采用了高效的挤压制坯+终锻成形工艺,通过叶片锻造成形试验,试制出了具有均匀且状态理想的金相组织、良好表面质量的TC8合金转子叶片锻件,表明了所制定的叶片成形工艺及工艺参数合理可行.     

第四代粉末高温合金热变形后的"项链"组织

利用扫描电镜、透射电镜及电子背散射衍射技术研究新型第四代粉末高温合金等温锻造后的"项链"组织,对其形成机理和消除方法进行了探讨。结果表明,实验合金经过多火次等温锻造后,锻坯大部分区域为再结晶后的等轴细晶组织;然而与模具接触的上下端面得到再结晶不完全的"项链"组织,在非等轴变形晶粒周围分布着大量细小的再结晶晶粒,变形晶粒内含有较高密度的小角度晶界,缠结了大量位错。对存在"项链"组织的试样进行不同温度(1080～1180℃)的退火处理,随着温度的升高,再结晶体积分数和再结晶晶粒尺寸均不断增大。合金锻坯经过1150℃再结晶退火后,可基本消除"项链"组织,获得组织较均匀的细晶盘坯,满足双组织热处理的要求。     

均匀化处理对新型Al-Zn-Mg-Cu铝合金组织及锻造性能的影响

采用扫描电镜观察(SEM)、透射电镜(TEM)、高温拉伸性能和高温冲击性能测试等方法,研究了不同均匀化处理工艺对一种采用常规半连续铸造方法生产的新型Al-Zn-Mg-Cu合金组织和锻造性能的影响。结果表明:随均匀化温度的升高,合金铸锭中的枝晶组织及难溶非平衡共晶相逐渐溶入基体中;当均匀化温度低于450℃时,基体中仍残留部分枝晶组织,并且合金的工艺塑性偏低;当均匀化温度达到470℃时,枝晶组织充分回溶到基体中,使铸锭获得最优的工艺塑性。铸锭经470℃/36h均匀化处理后,通过工艺塑性实验确定合金在380~430℃之间具有良好的锻造性能。根据以上实验结果,确定该新型Al-Zn-Mg-Cu合金的均匀化处理工艺为470℃/36h;锻造温度为380~430℃。     

Nb和Ta合金化对CoCrFeNi高熵合金组织和力学性能的协同作用

采用真空电弧熔炼法制备CoCrFeNi-(Nb,Ta)系列高熵合金,详细研究Nb和Ta合金化对CoCrFeNi基高熵合金组织演变和力学性能的协同效应。Nb/Ta合金化方式影响(CoCrFeNi)₈₈Nb_x Ta₍(12-x))合金的组织组成、共晶相片层间距、Laves相的尺寸形貌、两相体积分数及成分组成。Nb,Ta含量为等原子比时,合金组织组成为FCC+Laves两相共晶组织;Nb,Ta含量为非等原子比的合金则呈现为共晶(FCC+Laves)相和初生Laves相的组织结构,初生Laves相的体积分数和晶粒尺寸随Nb/Ta原子比的增加而单调增加。研究合金的压缩屈服强度与Laves相体积分数正向相关,压缩断裂强度几乎不受组织组成的影响,压缩塑性则与Laves相的体积分数、类型与尺寸分布呈现负相关。计算分析CoCrFeNi-(Nb,Ta)高熵合金的强化机制,探讨合金组织组成对其强度的作用规律。分析表明,细晶强化和Laves相的第二相强化是提升合金屈服强度的主要因素。     

TA5合金板材工艺对显微组织和力学性能的影响

研究了TA5合金板材的加工、退火及热矫形工艺对组织和力学性能的影响。结果表明:板坯第2火次锻造在相变点以上150℃变形,造成板材组织粗化,呈纤维状,强度非常高,塑性变化不大;换向轧制的板材组织均匀等轴化,再结晶晶粒尺寸增加,强度显著降低,塑性明显升高;随着精轧温度的升高,再结晶晶粒均匀化长大趋势明显,板材强度降低,塑性升高;为了避免热矫形过程对板材组织性能的影响,退火温度应高于热矫形过程中的料温;板材经过二次或三次热矫形后,不平度可达到(2~3) mm/m,室温力学性能基本不变。      

马氏体时效钢带状组织产生的原因及消除方法

马氏体时效钢具有超高强度和良好的综合性能。但是,该合金在锻造成形过程中存在大量带状组织,这种组织严重影响了材料的使用性能,如使材料各向异性,塑性降低,冲击韧性及断面收缩率下降等。本文重点探讨了带状组织产生的内因,并通过热处理工艺试验探索了消除带状组织的方法,试验研究表明,合金经过1050℃×2h＋820℃×1h热处理后,材料的带状组织基本碎化或消除,组织和成分细小均匀,有效地改善了材料的力学性能。     

Microstructures and Tensile Properties of Isothermally-forgedTi-47Al-2Nb-1Cr-1V and Ti-47Al-2V-1Cr Alloys

Microstructures and room-temperature tensile properties of isothermally-forged γ-base (γ + α2)alloys in Ti-Al-Nb-Cr-V system with different heat treatments were investigated. The results show that the microstructures of Ti-47Al-2Nb-1Cr-1V and Ti-47Al-2V-1Cr (at. pct) alloys are mainly determined by heat treating temperature in the (cr + 7) tWo-phase field, and the joint additions of Nb, Cr and V in the Ti-47Al alloy afFect Ta significantIy. The microstructure of Ti-47Al alloy with additions of Nb, Cr and V (1~2 at. pct) can be dupIex or nearly-lamellar by a suitable heat treatment after isothermal forging at 1000℃ for over 50% plastic strains.Therefore its tensile properties can be improved at room temperature.     

FGH96合金反复镦拔与挤压缺陷对比分析

对FGH96合金反复镦拔变形与挤压变形两种制坯工艺的夹杂缺陷水平进行了比较,并分析了不同变形状态下非金属夹杂物的形变特性。结果表明:反复镦拔变形后,锻件内检测到的非金属夹杂物数量有不同程度的增多,超标缺陷成倍增长;而FGH96合金挤压+等温锻造变形后,锻件内检测到的非金属夹杂物数量明显减少,纯净度水平有大幅提高。从微观夹杂物形貌的变形特性来看,等温锻造变形时在垂直于变形方向合金中夹杂物缺陷的尺寸增大;反复镦拔变形时,合金中原有非金属夹杂物缺陷聚集使可检测到的缺陷面积增大;而在挤压变形过程中,夹杂物缺陷在挤出方向被拉长成不连续的线状,每个方向上夹杂物的面积均减小;FGH96合金挤压+等温锻造变形后夹杂缺陷的大小主要由挤压变形后夹杂缺陷破碎情况决定;因此大挤压比变形可有效破碎合金中非金属夹杂物,改善锻件质量。     

轿车左转向节锻造工艺的模拟研究

针对轿车左转向节是带细杆的叉形件,同时兼有叉类、盘类和杆类零件的外形特点,分析其成形的工艺特点,进行工艺计算,确定工艺方案为头部镦粗—杆部拔长—预锻—终锻.利用有限元软件对成形过程进行模拟,得到飞边均匀的终锻成形件,并对模拟得到的应力场、应变场和载荷等信息进行分析.结果表明,各工序变形较为均匀,应力变化正常,没有出现破坏现象;最终锻件完全充满终锻模膛,没有出现缺料、折叠等缺陷,而且飞边均匀.     

Microstructure optimization design methods of the forging process and applications

A microstructure optimization design method of the forging process is proposed. The optimization goal is the fine grain size and homogeneous grain distribution. The optimization object is the forging process parameters and the shape of the preform die. The grain size sub-objective function, the forgings shape sub-objective function and the whole objective function including the shape and the grain size are established, respectively. The detailed optimization steps are given. The microstructure optimization program is developed using the micro-genetic algorithm and the finite element method. Then, the upsetting process of the cylindrical billet is analyzed using a self-developed program. The forging parameters and the shape of preform die of the upsetting process are optimized respectively. The fine size and homogenous distribution of the grain can be achieved by controlling the shape of the preform die and improving the friction condition.     

钛合金双安装板静子叶片精锻成形工艺优化

为了缩短双安装板结构的TC4合金低压第二级静子叶片精锻工艺流程,并得到更优的金相组织、力学性能,首次将等温锻造方法引入叶片精锻工艺中,采用一火次等温预锻代替两火次普通预锻.利用刚粘塑性有限元法模拟等温预锻过程,分析了金属流动规律、应变场等的变化情况.结果表明,所成形的等温预锻件应力较低、应变分布比较均匀.经叶片成形工艺试验,得到了采用等温预锻的叶片精锻件,将采用普通预锻的叶片精锻件与之对比,发现采用等温预锻的叶片较采用普通预锻的叶片金相组织均匀性好,而两者的力学性能相当.     

In situ X-ray analysis of mechanism of nonlinear super elastic behavior of Ti–Nb–Ta–Zr system beta-type titanium alloy for biomedical applications

Ti–XNb–10Ta–5Zr (mass %) alloys based on nominal compositions of Ti–35Nb–10Ta–5Zr, Ti–30Nb–10Ta–5Zr, and Ti–25Nb–10Ta–5Zr were fabricated through powder metallurgy and forging and swaging processes for biomedical applications. The tensile deformation mechanisms of the Ti–25Nb–10Ta–5Zr, Ti–30Nb–10Ta–5Zr, and Ti–35Nb–10Ta–5Zr alloys were investigated in situ by X-ray diffraction analysis under several loading conditions.Under the loading conditions, the X-ray diffraction peaks of all the specimens shifted to higher angles than those obtained under the unloading conditions. For the Ti–30Nb–10Ta–5Zr alloy, the elastic deformation is considered to progress continuously in a different crystal direction although after the elastic strain reaches elastic limit in the crystal direction where the elastic limit is the smallest, slip deformation occurs in that crystal direction. The elastic modulus of this alloy appears to decrease in terms of strain over the proportional limit. Thus, the elastic deformation behavior of the Ti–30Nb–10Ta–5Zr alloy does not obey Hooke's law.     

Microstructures and properties of semisolid billet and thixoforging product prepared by vibrating wavelike sloping plate (VWSP) process

By using self-made vibrating wavelike sloping plate (VWSP) setup, the process of preparing semisolid billets of light alloys by semi-continuous casting and thixo-forging process were studied. Semisolid billets with fine spherical or rosette grains were prepared by the proposed process, and the solidified shell on the sloping plate surface can be effectively avoided. During the casting process, due to metal flow and vibrating, burst nucleation in the whole melt and dendrite fracture take place, which causes the formation of fine spherical microstructures. Casting temperature, vibrating amplitude, sloping plate length and sloping angle are the main factors influencing the alloy microstructure. Under the current experimental conditions, the proper casting temperature ranges of 660°C–680°C, the amplitude value smaller than 2 mm and the proper sloping angle ranges of 40°–60° are suggested. When the reheating temperature is 575°C and the holding time is 60 min for AZ91D alloy, and 597°C and 90 min for Al-6Si-2Mg (wt.%) alloy, the semisolid forging process can be successfully implemented. Thixo-forming products of such two alloys are fine with smooth appearance, good microstructures and properties.