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Study on High Temperature Strength of Oxide-Dispersion-Strengthened Mechanical Alloy

氧化物弥散强化机械合金高温强度研究

基本信息

批准号：
63460073
负责人：
OHTANI Ryuich
金额：
$ 4.1万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

1. Crack propagation tests were conducted in creep-fatigue at 900 ﾟC and 1000 ﾟC in air using notched plate specimens of nickel base superalloy, Inconel MA754, which was an oxide (Y_2O_3) dispersion strengthened alloy made by mechanical alloying. The grains were elongated by directional recrystallization during the annealing process. As the crack tip approached a grain boundary perpendicular to the propagation direction on the specimen surface, the crack propagation drastically decelerated and temporarily halted. It implied that the grain boundaries were obstacles to the propagation. Despite of the microstructural inhomogeneity, the total area of crack increased smoothly because the randomness was averaged along the crack front through the specimen thickness of 5mm (10 grain diameters). The average crack propagation rate was correlated well with creep J-integral range which was a non-linear fracture mechanics parameter and represented the intensity of creep strain in the vicinity of crack tip.2. The crack propagation tests were conducted in creep-fatigue at 800ﾟC and 900ﾟC in air using notched plate specimens of Inconel MA754 without the directional recrystallization and base alloy without the oxide particle dispersion, Nimonic 75. The cracks propagated smoothly and the propagation rate was correlated well with the creep J-integral range. The relations coincided with that of directionally recrystallized Inconel MA754 was far superior to the others in terms of the high temperature strength.3. A stochastic model was developed for the random initiation and propagation of small cracks due to the microstructural effect. Three dimensional simulation was numerically carried out and the validity of model was examined by comparisons with experimental observation.

1.用机械合金化制备的氧化物（Y_2O_3）弥散强化的镍基高温合金InconelMA754缺口板试样，在900 ℃和1000 ℃空气中进行了蠕变疲劳裂纹扩展试验。在退火过程中，晶粒被定向再结晶拉长。当裂纹尖端接近与试样表面上的扩展方向垂直的晶界时，裂纹扩展急剧减速并暂时停止。这意味着晶界是传播的障碍。尽管显微组织的不均匀性，裂纹的总面积平稳增加，因为随机性是平均沿着裂纹前沿通过试样厚度为5 mm（10个晶粒直径）。平均裂纹扩展速率与非线性断裂力学参量蠕变J积分幅值有很好的相关性，它代表裂纹尖端附近蠕变应变的强度.在空气中，使用无定向再结晶的Inconel MA 754和无氧化物颗粒分散的基础合金Nimonic 75的缺口板试样，在800 ° C和900 ° C的蠕变疲劳中进行裂纹扩展试验。裂纹扩展平稳，扩展速率与蠕变J积分范围有很好的相关性。这与定向再结晶Inconel MA754合金的高温强度关系相上级.建立了考虑微结构效应的小裂纹随机萌生和扩展的随机模型。通过与实验观测结果的比较，验证了模型的有效性。