Important Factors Affecting the Stability of Substructure in Heat-resistant Materials

影响耐热材料亚结构稳定性的重要因素

基本信息

批准号：
15560602
负责人：
ENDO Takao
金额：
$ 2.11万
依托单位：
National University Corporation Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

In the project term, we confirmed that the growth of subgrain during creep (i.e., degradation of substructure) and the Ostwald ripening observed in a heat resistant steel, Al-Cu alloys and a commercial magnesium alloy were all strain dependent notwithstanding that attention was not paid to the effect of strain on the structural degradation so far. Furthermore, the critical stress necessary for subgrain boundary to escape from pinning of precipitates was examined. The results showed that the subrain size remained unchanged in a stress range below the critical stress while it begins to increase in a stress range above the critical stress. On the theoretical basis, the critical stress is expected to be independent of testing temperature, however, the measured critical stress was temperature-dependent. In order to clear the reason for this temperature dependence, the average size and inter-particle spacing of precipitates were measured as a function of testing temperature. The experimental … More results showed that the inter-particle spacing increased with increase in testing temperature because particle coarsening occurred during heating to testing temperature before stress application. The analysis showed that the temperature dependence of critical stress was only apparent. The magnitude of critical stress was almost equal to the theoretical one calculated from the model proposed in Mater.Trans.44(2003),239-246.Since the structural degradation of T91 steel is associated with migration of subboundary, we can view that the structural degradation was promoted by dislocation motion (plastic strain). Actually, the origin of structural degradation of this type is seemingly different from the strain enhanced Ostwald ripening, however, we can view that the origin of both phenomena is the same because the growth of precipitates which hinder the sub-boundary migration can also be assisted by the motion of subboundary.Generally, many heat-resistant materials contain solute atoms with a relatively large size misfit. This is because solutes of this type are effective to strengthen their matrix, however, these solutes are liable to introduce the solute transport assisted by dislocation motion, and eventually lead to strain-enhanced growth of precipitates. So far, solutes with a relatively large size misfit were preferably added to heat-resistant materials to strengthen their matrix, however, these elements are susceptible to strain enhanced coarsening of precipitates. Strain enhanced structural degradation was not taken into account so far in alloy designing, however, it is important to re-consider the alloying elements taking into account the scavenging effect which causes the strain enhanced coarsening of precipitates. Less

在项目期间，我们证实，在耐热钢、铝铜合金和商用镁合金中观察到的蠕变过程中亚晶粒的生长（即亚结构的退化）和奥斯特瓦尔德熟化均与应变相关，尽管人们没有注意到这一点。此外，还考察了亚晶界摆脱析出物钉扎所需的临界应力，结果表明，在低于临界应力的范围内，亚晶界尺寸保持不变。在高于临界应力的应力范围内，应力开始增加。从理论上讲，临界应力预计与测试温度无关，但是，为了明确其原因，测得的临界应力与温度有关。这种温度依赖性，测量了沉淀物的平均尺寸和颗粒间间距作为测试温度的函数。实验结果表明，颗粒间间距随着测试温度的升高而增加，因为在加热至测试温度期间发生了颗粒粗化。分析表明，在施加压力之前。临界应力的温度依赖性只是明显的，临界应力的大小几乎等于根据 Mater.Trans.44(2003),239-246 中提出的模型计算的理论应力。因为 T91 钢的结构退化与从亚晶界迁移来看，我们可以认为结构退化是由位错运动（塑性应变）促进的。实际上，这种类型的结构退化的起源看似与应变增强的奥斯特瓦尔德熟化不同，但我们可以认为，结构退化的起源是由位错运动（塑性应变）推动的。这两种现象是相同的，因为阻碍亚晶界迁移的析出物的生长也可以通过亚晶界运动来辅助。通常，许多耐热材料含有尺寸较大的溶质原子，这是因为这种溶质。这类溶质可以有效强化其基体，但这些溶质容易引入位错运动辅助的溶质输运，最终导致析出物的应变增强生长。优选将错配添加到耐热材料中以强化其基体，然而，这些元素容易受到应变增强沉淀物粗化的影响，迄今为止在合金设计中尚未考虑到应变增强结构退化，但重要的是重新设计。考虑合金元素引起应变强化析出物粗化的清除作用。

项目成果

期刊论文数量（28）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Change in Vickers Hardness and Substructure during Creep of a Mod.9Cr-1 Mo Steel

Mod.9Cr-1 Mo钢蠕变过程中维氏硬度和亚结构的变化

DOI：
发表时间：
2003
期刊：
Mater.Trans. 44
影响因子：
0
作者：
Takao Endo;F.Masuyama;K-S.Park
通讯作者：
K-S.Park

Change in Vickers Hardness and Substructure during Creep of a Mod.9 Cr-1 Mo Steel

Mod.9 Cr-1 Mo 钢蠕变过程中维氏硬度和亚结构的变化

DOI：
发表时间：
2003
期刊：
Mater.Trans. 44[2]
影响因子：
0
作者：
Takao Endo;Fujimitsu Masuyama;Kyu-Seop Park
通讯作者：
Kyu-Seop Park

Accelerated coarsening of precipitates in crept Al-Cu alloys

DOI：
10.1016/j.msea.2004.01.131
发表时间：
2004-12-15
期刊：
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
影响因子：
6.4
作者：
Nakajima, T;Takeda, M;Endo, T
通讯作者：
Endo, T

T.Nakajima, S.Spigarelli, E.Evangelista, T.Endo: "Strain Enhanced Growth of Precipitates during Creep of T91"Materials Trans.. 44 No.9. 1802-1808 (2003)

T.Nakajima、S.Spigarelli、E.Evangelista、T.Endo：“T91 蠕变期间沉淀物的应变增强生长”Materials Trans.. 44 No.9。