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硕士论文-15Cr-25Ni-Fe基合金的热加工性及特大涡轮盘的镦饼工艺设计，共71页，39563字
摘要
作为国家‘863’重大课题即重型燃气轮机专项下面的一个子课题，本工作的研究
内容是制定直径达 2m 以上的燃气轮机用特大涡轮盘的热加工工艺。该涡轮盘采用的材
料是 GH2674 合金。鉴于这种合金目前在国内是首次应用，研究过程中首先系统地研究
了合金的热加工性能，得到能发挥合金最佳热加工性能的热变形参数范围。在此基础
上，结合国内实际生产条件，采用有限元数值模拟技术，对直径逾 2m，重量逾 4 吨的
特大涡轮盘坯的镦饼过程进行了研究。
本文首先通过一系列热压缩实验，研究了 GH2674 合金的热变形行为，获得了
GH2674 合金在不同温度和应变速率下的真应力－真应变曲线，结果表明流变应力对应
变速率具有很高的敏感性，对变形温度也具有一定的敏感性，受应变量的影响很小。采
用幂函数关系式可以很好地表达合金的流变应力与变形温度和应变速率的关系。
值得注意的是描述流变应力的幂函数关系式没有涉及到合金的热变形机制，不能解
释合金的热变形行为，不能得到优化的热变形参数。因此本文采用了动态材料模型的加
工图，对热变形过程中的热变形机制进行了系统的分析。
根据热/力模拟实验，测绘了 GH2674 合金的动态材料模型的加工图，并采用该图
研究了在 950-1200℃温度范围内和 0.001-10s-1 应变速率范围内不同区域内热变形的微观
机制，得到以下结论：
1) GH2674合金在热变形时呈现两个微观机制不同的动态再结晶峰区。其中动态再
结晶Ⅰ区：峰值效率为38%, 峰值对应的温度和应变速率为1040℃/10s-1；动态再
结晶Ⅱ区：峰值效率为40%，峰值对应的温度和应变速率为1075℃/0.04s-1。
2) 在应变速率小于0.01s-1、温度高于1050℃区域内，合金呈现晶粒急剧粗化现象，
进而导致楔形裂纹的产生。在应变速率高于0.1 s-1，形变温度低于1000℃的区间
内，合金有出现剪切变形带的趋势。在1075-1100℃温度区间内，由于晶界相的
溶解导致晶粒突然长大，这会在一定程度上影响合金的热加工性能。
上述两个动态再结晶区是 GH2674 合金的可加工区域，对应着热变形过程中重要的
组织演变机制和起主导作用的软化机制。因此，本文进一步研究了合金动态再结晶机制
和行为随温度和应变速率的变化规律。
由于应变速率不同，使两个动态再结晶区域的动态再结晶的形核位置和形核率(N)存
在很大差异，进而导致二者的动态再结晶控制过程有所不同，即应变速率较低的动态再
结晶区域受动态再结晶的形核过程控制；应变速率较高的动态再结晶区域受动态再结晶
的长大过程控制，最终形成了各自特有的金相组织。变形温度影响了动态再结晶过程的
N/G 值，进而影响了再结晶晶粒尺寸。同时变形温度对动态再结晶完成程度有明显影
响，最终影响了固溶处理后组织。
通过以上研究，建立了 GH2674 合金的热变形参数和热变形机制之间的对应关系。
根据这种对应关系，可以进行简单的工艺设计：建议优先选择动态再结晶区，避开加工
危险区和失稳区，因为动态再结晶区内的功率耗散效率较高，加工性能好，并且组织易
于控制。在动态再结晶Ⅰ区内适合通过轧制、挤压和锤锻等工艺加工合金板材、棒材和
饼材；而动态再结晶Ⅱ区对采用水压机加工大型盘类件时是适宜的。
通过以上对 GH2674 合金热加工性能的系统研究，采用有限元数值模拟技术，针
对特大涡轮盘锻件热加工过程的工艺难点，研究了 GH2674 合金涡轮盘整体镦饼工艺。
分析了不同工艺条件下镦饼过程中的设备载荷，应变场和温度的分布规律。在此基础
上，归纳得到了盘坯典型变形区域。通过控制典型变形区域的热加工性能从而达到了控
制整个盘件的热加工性的思路，制定了能发挥 GH2674 合金最佳热加工性能的工艺参
数。而在控制盘坯典型变形区域的热加工性能时，只要将其的热加工参数轨迹控制在动
态再结晶Ⅱ区的范围内即可。
关键词：铁基高温合金，热变形，加工图， 动态再结晶， 有限元数值模拟
Hot deformation behavior of a 15Cr-25Ni-Fe based alloy and
corresponding process of outsize turbine disk
Abstract
As part of a Heavy Gas Turbine Project, the task of this research is to design the hot
working processes of outsize turbine disk used for heavy gas turbine, the diameter of which is
over 2 meters and the weight is over 4 tones. As the GH2674 alloy used is new in China, its hot
deformation behavior was studied systemically at first to obtain the temperature and strain rate
range which suit the constitutive requirements of this alloy from view point of optimum
workability and microstructural control for hot working. On this basis, combined with the actual
manufacture condition, the forging process of this type of outsize turbine disk billet was
researched and designed by numerical simulation technique (FEM).
By hot compressing testing on a Gleeble-1500 simulator, the true stress-true strain curves
were obtained and the hot deformation behavior of GH2674 in the temperature range of 950-
1200℃ and strain rate range of 0.001-10 s-1 was studied. The results show that, the flow stress is
very sensitive to strain rate, less sensitive to temperature and not sensitive to strain. Flow stress
in hot deformation can be related to strain rate and temperature through an Arrhenius type of
rate equation
It is noticeable that this equation has offered no information on deformation mechanisms of
the alloy. So it does not specifically lead to optimization of intrinsic workability. Therefore the
processing map of dynamic materials model (DMM) has been used to reveal the deformation
mechanism and microstructure evolution.
On the basis of the hot compressing experimental data and by using the principles of DMM,
the processing map of GH2674 alloy was developed in the temperature range of 950-1200℃
and the strain rate range of 0.001-10 s-1. The map exhibits two important domains, with their
peaks locating at 1050℃ and 0.01 s-1 with a peak efficiency of power dissipation of 38%, and at
1150℃ and 10s-1 with a peak efficiency of 40%, respectively. On the basis of optical
microscopic observations, the two domains are interpreted to represent two dynamic
recrystallization (DRX) domains with different mechanisms. The map also exhibits a long
concave band in the temperature range of 1075-1100℃，which may be related to the
solutionizing of M3B2 phase. At temperatures lower than 1000℃ and strain rates higher than
0.1s-1, the material may be subjected to potential instabilities, while at temperatures higher than
1050℃ and strain rates lower than 0.01s-1, the material exhibits significant grain coarsening.
Furthermore, the wedge cracking would appear at 1200℃ and 0.001s-1.
As the DRX is the main softening mechanism and corresponds to the important
microstructural reconstruction during hot deformation, the above two DRX domains are the
workable range of GH2674 alloy. Therefore, study on the DRX mechanism and hot
deformation behavior of this alloy with different temperatures and strain rates was further
carried out.
Due to the strain rate differenence of the two DRX domains, their DRX nucleation sites and
rates are also different, which lead to different control mechanisms of the DRX process. In the
lower strain rate DRX domain, the process is mainly controlled by the nucleation process; in the
higher strain rate one, the process is mainly controlled by the growth process. As a result,
different microstructures would form corresponding to the two DRX domains. The deformation
temperature has the effects on the DRX through two ways. First, the increase of temperature
leads to the decrease of the N/G value of the DRX and, furthermore, leads to the increase of
average DRX grain size; second, the deformation temperature has a great effect on the
completeness of the DRX, which can influence the microstructure after solution treatment.
On the basis of the constitutive behavior of GH2674 alloy as revealed above, the relation
between the hot deformation parameter and the mechanism can be established, and the hot
working schedules were designed primarily. The process should be controlled so that the local
values of temperature and strain rate fall within the DRX domains, and the undesirable regimes
such as flow instability or cracking are avioded. On the basis of the strain rate of the available
hot pressing equipment in China at present, it is suitable to product sheets, bars and disks of
GH2674 alloy by rolling, extruding and hammer forging in DRXⅠdomain; while the outsize
disks are better upsetted by hydraulic pressing in DRXⅡdomain.
After the hot workability studied, further research work were conducted to design the key
process, i.e. the hot upsetting process, of the outsize GH2674 alloy turbine disk billet using FE
simulation technique. The load force and the distribution of the temperature and strain were
analyzed under different process conditions. Then the typical deformation areas in the forged
pieces were identified. By limiting these typical areas’ deformation temperature-strain rate
trajectories within the DRXⅡdomain, the optimum parameters of the hydraulic pressing
process were designed for the upsetting process of the outsize turbine disk billets.
Key Words： Fe-based superalloy, hot working, processing map, dynamic
recrystalliztion, finite element simulation
目录
摘要......... 1
Abstract.. 3
1 导论 ....... 1
1.1 合金热加工研究概述...... 1
1.2 热变形机制概述 ... 1
1.2.1 动态再结晶. 1
1.2.2 动态回复...... 2
1.1.3 超塑性变形.. 3
1.2.4 微观裂纹..... 4
1.2.5 其它变形机制 ....... 4
1.3 热变形模型研究概述..... 5
1.3.1 动态材料模型(DMM)及其加工图 .. 5
1.3.2 动力学模型. 7
1.3.3 热变形激活能模型 ........ 8
1.4 合金热变形工艺设计..... 9
1.5 本研究的工作简介....... 11
1.5.1 课题背景简介 .... 11
1.5.2 本研究的主要目的 ...... 11
1.5.3 本研究的工作内容 ...... 12
2 热压缩实验与热变形行为分析 ..... 13
2.1 热变形行为的等温恒应变速率压缩实验研究 .. 13
2.1.1 实验材料.... 13
2.1.2 实验条件.... 14
2.1.3 实验数据处理和微观组织观察 ...... 15
2.2 热变形行为分析 . 15
2.2.1 流变应力曲线 .... 15
2.2.2 GH2674 合金的峰值应力...... 17
2.2.3 GH2674 合金不同应变量下的变形行为. 21
2.3 本章小结 ... 21
3 GH2674 热变形机制分析...... 22
3.1 GH2674 合金热加工图的建立 ........ 22
3.2 GH2674 合金的热加工图分析 ........ 23
3.2.1 加工图中的峰区 23
3.2.2 加工图中的加工危险区........ 25
3.2.3 加工图中的加工失稳区........ 26
3.2.4 加工图中的其它区域 .. 27
3.2.5 工艺优化设计原则 ...... 29
3.4 本章小结 ... 30
4 GH2674 合金动态再结晶行为研究 ......... 31
4.1 动态再结晶的热变形表观激活能研究 .... 31
4.2 GH2674 合金热变形动态再结晶显微组织与机制研究....... 33
4.2.1 应变速率对动态再结晶的影响 ..... 33
4.2.2 变形温度对动态再结晶的影响 ..... 36
4.3 本章小结 ... 40
5 GH2674 合金涡轮盘的镦饼预成型工艺研究... 41
5.1 涡轮盘的镦饼预成型工艺概述....... 41
5.2 整体锻压过程有限元数值模拟....... 42
5.2.1 镦饼过程载荷预测 ...... 42
5.2.2 镦饼过程应变场和温度场研究 ..... 44
5.2.3 镦饼过程热加工性能控制.... 46
5.2.4 水压机镦饼工艺制定和优化 48
5.3 局部旋压过程有限元模拟 .... 50
5.3.1 局部锻造成型过程中锻件的几何形状... 50
5.3.2 局部锻造成型过程中锻件的应变场分布......... 52
5.4 本章小结 ... 54
6 结 论 ......... 56
参 考 文 献. 58
在学期间研究成果 63

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