GH4169合金精锻叶片腐蚀条带组织的成因分析及预防措施

目的 分析精锻工艺成形的GH4169合金压气机转子叶片出现腐蚀条带组织的原因,以制定相应的预防措施。方法 对精锻叶片用GH4169合金开展锻造热过程模拟试验,采用电镜观察其显微组织,以判断叶片锻件异常组织与原材料组织的关联。采用数值模拟方法对锻造工艺参数,尤其是锻造变形量进行分析与验证,找出锻造工艺方案的不足之处。结果 当原材料存在δ相偏聚时,容易导致叶身及榫头部位出现纵向腐蚀条带组织;当叶片锻造变形设计不合理,盆弧侧、背弧侧的预锻件与终锻件的变形体积比超出1.1～1.4时,会导致榫头部位出现金属流动异常的现象,进而产生应变剪切带、导致叶片榫头部位出现异常组织。结论 在叶片精密锻造生产前要确保原材料组织均匀,不能出现δ相偏聚,同时采用数值模拟方法来合理控制锻造各阶段的变形量与应变场,确保叶片预锻件与终锻件的变形体积比合理、金属变形均匀,这样才能保证叶片叶身和榫头部位不出现腐蚀条带组织。     

1420铝锂合金模锻件锻造工艺的研究

利用高温变形实验,研究了1420铝锂合金在不同变形条件下的变形行为,获得合金的塑性图、变形抗力图、晶粒尺寸-变形程度关系图,确定出合金的锻造工艺参数:锻造温度为350～420℃,临界变形程度为8%～10%,变形速率以低速为宜.结合实际情况,制定出合理的、经济的1420铝锂合金模锻件成形工艺,即6000t水压机上多方锻开坯→车成锥体→8000t卧式挤压机上终压模成形.生产出的1420合金模锻件尺寸精度高,综合性能优良.     

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.     

TC6钛合金带阻尼台叶片等温模锻件研制

研究了等温锻造及热处理工艺对TC6钛合金组织和性能的影响,研究结果表明,锻坯加热温度的提高会导致合金中的α相含量减少,延长保温时间对合金中α相含量影响较小;在相变点温度以下45～65℃加热保温并经适当程度的等温锻造变形后,合金中a相含量可以保持在30％以上,并具有良好的力学性能;进行热处理时,冷却速率和热处理温度对合金性能有较大影响;经合适的双重退火处理后,合金具有良好的组织和综合性能.     

热压工艺参数对TC11钛合金饼坯低高倍组织的影响EI

本文研究了常规锻、等温锻和超等温锻工艺参数对TC11钛合金饼坯高、低倍组织的影响。试验研究结果表明,采用等温锻造(锻造加热温度为930℃或860℃)或超等温锻(锻造加热温度860℃,模具温度930℃),可使饼坯获得均匀细晶的低倍组织和。α+β等轴高倍组织。     

BT20合金高温变形行为的研究

为实现BT20合金锻造的数值模拟和合理制定其热成形工艺参数,利用Thermecmastor-Z型热模拟试验机对该材料在热成形条件下的变形抗力进行了研究,考察了变形温度、应变速率及变形程度与变形抗力之间的关系,并利用冶金学方法对其进行了分析.结果表明,应变速率和变形温度的变化强烈影响着合金流变应力的大小,流变应力随变形温度升高而降低,随应变速率提高而增大.通过真实σ-ε曲线,回归出可综合反映锻造热力参数对材料成形性能影响的本构方程.     

钛合金多向锻造数值模拟

目的研究TC4钛合金在多向锻造过程中的变形行为。方法基于Deform-3D模拟软件平台,对钛合金的多向锻造变形过程进行有限元模拟分析,研究不同工艺参数(锻造温度、锻造速度、锻造工步)下合金最大主应力、等效应变和载荷最大值的变化规律。结果多向锻造的每工步锻造为典型的镦粗过程,坯料中心部位一直受压应力作用,鼓肚处则出现最大拉应力。随着锻造温度的升高和锻造速度的减小,最大压应力和拉应力均减小,多工步锻造之后合金主应力场分布更加均匀。随着锻造工步的增加,坯料等效应变增大且中心大变形区域体积分数增加。最大载荷随锻造温度的升高和锻造速度的降低而减小,相同参数下不同锻造工步的载荷最大值变化不大。结论锻造温度、锻造速度、锻造工步对TC4钛合金多向锻造变形行为有显著的影响,适当选择多向锻造工艺参数,可以降低载荷并获得均匀性较好的坯料。     

LC4铝合金呆扳手成形热力学参数的确定

通过试验研究了LC4铝合金呆扳手成形的温度、变形程度、变形速度、加热方式和加热速度等成形热力学参数与成形质量之间的关系.解决了试验过程中出现的一些问题,确定了最佳成形工艺参数为:始锻温度400～450℃、终锻温度350℃左右,第1阶段的变形量为30%～50%,第2阶段的变形量为75%.     

基于响应面法的铝合金筋板锻件工艺参数多目标优化

为了能获得更好的铝合金筋板类锻件锻造成形工艺参数,提出了基于响应面法(Response Surface Methodology,RSM)和有限元模拟技术(finite element simulation,FEM)的锻造成形工艺参数多目标优化策略.以铝合金筋板类锻件晶粒均匀性和锻造变形力作为评价指标,建立了有限元数值模拟与响应面法相结合的二阶分析模型,求得的回归模型拟合度达89.59%.并运用MATLAB软件求出可行设计空间中目标函数最佳工艺参数组合为始锻温度465℃、锻造速度8.7 mm/s、摩擦系数0.2.锻件的晶粒均匀性有了很大的改善,同时有效的降低了锻件变形力,并通过DEFORM-2D模拟和热加工图对其进行了验证,表明了所提出方法的有效性.     

高温合金叶片精密成形技术研究

采用挤杆、镦头制坯、预锻、终锻成形的工艺方法,实现了叶片单面余量(0.5±0.2)mm的精密成形.通过变形温度、变形程度对锻件组织性能影响的研究,确定了最佳热工艺参数;通过热处理工艺试验、锻件的表面状态及硬度的检测,确定了热处理工艺参数和冷却方式.锻件的首批试制结果表明,试制出的叶片锻件,金相组织和机械性能均符合锻件技术条件要求,与国外原件的组织状态基本一致.通过了振动疲劳2×107循环考核和发动机的长期试车考核.     

Microstructure and mechanical properties of TA15 titanium alloy under multi-step local loading forming

In this paper six different local loading processes were proposed to study the effects of local loading conditions (temperature, deformation degree, loading pass, heats, cooling modes and heat treatment) on the microstructure and mechanical properties of TA15 titanium alloy workpieces including room and high temperature tensile properties, impact property, fracture toughness and high temperature duration property.It is found that it is better to finish the local loading forming in one heating time, if multi-fire forging needed the optimal forging technique as follows: adopting conventional forging (950 °C) at first and then following near-beta forging to control the proportion of the equiaxed primary α phase and the transformed β phase, allocating deformation degree of each loading pass rationally and using WQ cooling mode. Thus the workpiece with good compositive mechanical properties can be obtained.     

Effect of process parameters on microstructural variables of a commercial TC6 titanium alloy disc

Abstract

The interaction between the deformation behaviour and the microstructure evolution is the main characteristic in the forging process of titanium alloy and this interaction is researched using finite element (FE) simulation. Coupled simulation of deformation behaviour with microstructure evolution has been carried out by means of a new constitutive equation presented by Li et al. (Mater. Sci. Technol., 2004, 20, 1256–1260). The effect of deformation temperature, hammer velocity,height reduction and shear factor on the microstructure variables, including grain size and volume fraction, has been studied in the forging process of the TC6 titanium alloy disc with deformation temperatures of 880–940°C, hammer velocities of 1·2–12 000 mm min^?1 and shear factor (m) of the friction of 0·1–0·4. The simulated results show that deformation temperature, hammer velocity and height reduction have a significant effect on themicrostructure evolution and this effect is more significant on the microstructure evolution in hot forging than that in isothermal forging. The simulated results are in good agreement with the experimental results.     

FE simulation for the forging process of TC6 alloy disc utilising a microstructural model

The interaction between the deformation behavior and microstructural evolution is the main characteristic in the forging process of a titanium alloy and the interaction can be researched using FE simulation. In this paper, a constitutive equation, considering the effects of grain size on the deformation behavior, is established for high temperature deformation of titanium alloys. Also, FE simulation of deformation behavior combined with heat transfer and grain size in the forging process of TC6 alloy disc is carried out. By FE simulation, the deformation distribution and grain size were illustrated for the forging of a TC6 alloy disc at 920 °C deformation temperature and 2.0 mm/s of hammer velocity. The calculated deformation load and grain size are in a good agreement with the experimental results.     

Effects of Process Parameters on the Temperature Field in Ti-6Al-4V Alloy Blade Precision Forging Process

Blade precision forging is a high temperature and large plastic deformation process. Process parameters have a great effect on temperature distribution in billet, so in this paper, by taking a Ti-6Al-4V alloy blade with a tenon as an object, the influence of process parameters on the temperature distribution in precision forging process was investigated using 3D coupled thermo-mechanical FEM （finite element method） code developed by the authors. The results obtained illustrate that： （1） the gradient of temperature distribution increases with increasing the deformation degree; （2） with increasing the initial temperature of the billet, the zones of high temperature become larger, and the gradient of temperature distribution hardly has any increase; （3） friction factors have little effect on the distribution of temperature field; （4） with increasing upper die velocity, temperature of the billet increases while the temperature gradient in billet decreases. The results are helpful to the design and optimization of the process parameters in precision forging process of Ti-alloy blade.     

TC11钛合金盘模锻过程微观组织的数值模拟

通过热力模拟压缩试验和定量金相组织测试数据,运用BP神经网络方法建立TC11钛合金等轴组织两相区变形的流变应力模型和α相组织演变模型.将所建立的流变应力模型和α相组织演变模型集成到MARC有限元分析软件中,实现TC11钛合金等轴组织两相区变形-传热-微观组织演变的多场耦合模拟技术.采用该技术模拟预测TC11钛合金盘模锻后的α相晶粒尺寸,实验验证结果表明预测误差在10%以内.     

Effects of Process Parameters on the Temperature Field in Ti-6A1-4V Alloy Blade Precision Forging Process

Blade precision forging is a high temperature and large plastic deformation process. Process parameters have a great effect on temperature distribution in billet, so in this paper, by taking a Ti-6Al-4V alloy blade with a tenon as an object, the influence of process parameters on the temperature distribution in precision forging process was investigated using 3D coupled thermo-mechanical FEM (finite element method) code developed by the authors. The results obtained illustrate that: (1) the gradient of temperature distribution increases with increasing the deformation degree; (2) with increasing the initial temperature of the billet, the zones of high temperature become larger, and the gradient of temperature distribution hardly has any increase; (3)friction factors have little effect on the distribution of temperature field; (4) with increasing upper die velocity,temperature of the billet increases while the temperature gradient in billet decreases. The results are helpful to the design and optimization of the process parameters in precision forging process of Ti-alloy blade.     

TC11钛合金压气机盘闭模锻造过程中的缺陷预测

TC11钛合金压气机盘在实际生产中存在各种缺陷,降低了压气机盘的使用性能.将基于试验数据建立的TC11钛合金高温塑性变形时的延性损伤演化模型以及本构模型与有限元相结合,对某TC11钛合金压气机盘等温闭模锻造过程中的温度、等效应变和损伤变量的分布进行了数值分析,同时预测了塑性失稳区的位置.为优化其成形工艺提供了一种有效的方法.     

GH141合金环形锻件轧制工艺参数的研究

采用小环模拟的方式，研究了ＧＨ１４１合金轧制工艺参数中变形温度、变形程度对合金组织性能的影响，总结了ＧＨ１４１合金环形锻件的轧制工艺参数。