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STRAIN ENHANCED GROWTH OF PRECIPITATES CONTRIBUTING TO THE SUBSTRUCTURE STABILITY OF HIGH STRENGTH HEAT RESISTANT MATERIALS

应变增强的析出物生长有助于高强度耐热材料的组织稳定性

基本信息

批准号：
13650755
负责人：
ENDO Takao
金额：
$ 2.3万
依托单位：
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：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Advanced heat resistant steels usually contain fine subgrains and densely populated dislocations, which are both introduced during martensitic transformation. Their excellent high temperature strength is ascribable mainly to the substructure and precipitation strengthening. It is important to note that the thermal stability of substructure is controlled by the coarsening rate of precipitates which can retard the dislocation motion and the migration of subboudaries. A recent study on T91 suggests that the rate of coarsening is dependent on creep strain. The present study was undertaken to examine whether or not the coarsening rate of precipitates is strain dependent, and what mechanisms is likely to occur. Within the project term, three items were examined ; (1) analysis of existing data on T91, (2) experimental study and analysis on Al-Cu and magnesium alloys, and (3) numerical simulation of dislocation motion with solute atmosphere. From the studies on Al-Cu and magnesium alloys, confirmation was made that the coarsening rate of precipitates was strain dependent, and the effect of strain on coarsening became gentle when strain rates were higher. Based on the assumption that the dislocation motion with solute atmosphere enhanced the solute transport and lead to the enhancement of coarsening rate, a model was proposed. The model explained the experimental results satisfactorily.

高级耐热钢通常含有细小的亚晶和密集的位错，这两者都是在马氏体转变过程中引入的。其优异的高温强度主要归因于亚结构和沉淀强化。值得注意的是，亚结构的热稳定性是由沉淀的粗化速率控制的，它可以延缓位错运动和亚边界的迁移。最近对T91的研究表明，粗化速率取决于蠕变应变。本研究的目的是研究析出物的粗化速率是否与应变有关，以及可能发生的机制。在项目期限内，审查了三个项目；(1)对T91已有数据进行分析；(2)对Al-Cu和镁合金进行实验研究和分析；(3)对溶质气氛下位错运动进行数值模拟。通过对Al-Cu和镁合金的研究，证实了析出相的粗化速率与应变有关，应变对粗化的影响随着应变速率的增大而减小。基于位错在溶质大气中的运动增强了溶质输运，导致粗化速率的提高的假设，提出了一个模型。该模型较好地解释了实验结果。