Recoating and Refurbishment of Single crystal Ni- Based Superalloys for Advanced Gas Turbines

先进燃气轮机用单晶镍基高温合金的重涂和翻新

基本信息

批准号：
10650078
负责人：
OKAZAKI Masakazu
金额：
$ 2.24万
依托单位：
The University of Tokyo (1999)Nagaoka University of Technology (1998)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

This work has been conducted to make clear the formation of the abnormal microstructure, or cellular transformation, resulting from the local plastic deformation in single crystal Ni-base superalloys, CMSX-2 and CMSX-4, in order to get fundamental understanding to establish the refurbishment technology for advanced gas turbine components. During the study special attention was paid to get understandings on the nucleation and growth behavior from viewpoints of crystallography and thermo dynamics. The relationship between the transformation and the actual failure damages was also explored. Furthermore, the effect of the local cellular transformation on high temperature fatigue strength was investigated.The conclusions obtained are summarized as follows :(1) When CMSX-2 and CMSX-4 were subjected to damages associated with local plastic deformation, followed by the re-heat treatments, the cellular transformation associated with γ/γ' microstructure coarsened in lamellar or equiaxed array wa … More s originated. This was not a special phenomenon, but it was actually reproduced in the material subjected to fatigue and thermo-mechanical fatigue damages.(2) The transformation was originated and developed with high anisotropy, being influenced by the following many factors : i.e., the strain field by the local plastic deformation, the crystallographic orientation, the re-heat treatment temperature and time, and the microsegregation in the material. The γ'-solvus in the reheating process drastically accelerated the local recrystallization.(3) The shearing of γ' precipitates in the straining process may play an intrinsic role in the cellular transformation : when the {111}<110> systems were activated, the formation was significant. When the {100}<110> slip systems were activated such as in creep failure at higher temperature, on the other hand, it was negligible.(4) The growth of the transformation was successfully represented by the Johnson-Mehl type equation. The growth of the transformation must be controlled by diffusion process of A1 and Ni, where activation energy was determined by about 36 kcal/mol.(5) The small fatigue crack propagation rate was remarkably enhanced at the transformed region. Less

进行了这项工作是为了清除异常微结构或细胞转化的形成，这是由于单晶Ni-base Superalys，CMSX-2和CMSX-4的局部塑性变形而产生的，以便获得基本的理解，以建立高级燃气轮机组件的翻修技术。在研究中，特别注意从晶体学和热动力学的角度来了解成核和生长行为。还探索了转换与实际故障损害之间的关系。此外，研究了局部细胞转化对高温疲劳强度的影响。所获得的结论总结如下：（1）当CMSX-2和CMSX-4受到与局部塑性变形相关的损害时，将其与重新加热处理相关的损坏，然后由coarsed coarseare coarsear或等于等等。这不是一个特殊的现象，但实际上是在受到疲劳和热机械疲劳损害的材料中复制的。（2）转化是在最初具有高各向异性的高端开发的，受到以下许多因素的影响：即，通过局部塑性变形，晶体方向和时间，并在材料中进行了材料，并在本质上和时间，并在实际的治疗中，并进行了实际，并进行了实际的处理。在重新加热过程中γ'-溶剂急剧加速了局部的重结晶。（3）应变过程中γ'沉淀物的剪切可能在细胞转换中起固有的作用：当激活{111} <110>系统时，激活了该系统时，形成很大。另一方面，当{100} <110>滑移系统被激活时，例如在较高温度下的蠕变故障时，它可以忽略不计。（4）转换的生长成功地由Johnson-Mehl型方程表示。转化的生长必须由A1和Ni的扩散过程控制，其中活化能由约36 kcal/mol。（5）在转化的区域中，小疲劳裂纹的传播速率显着提高。较少的