Evaluation of Fatigue Properties in Future Aircraft Material, Aluminum-Lithium Alloy

未来飞机材料铝锂合金的疲劳性能评价

基本信息

批准号：
01550057
负责人：
OGAWA Takeshi
金额：
$ 1.28万
依托单位：
Gifu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1991
项目状态：
已结题

项目摘要

Wide range of fatigue properties under rotating bending were investigated in two kinds of aluminum Lithium (Al-Li) alloys, 2090 and 8090, which are predicted to be used for the future aircraft. The results were compared with the conventional aluminum alloys, 2024 and 7075. The results obtained are summarized as follows ;1. Tensile strength of the AI-LI alloys were approximately the same as those of 2024 alloy, but were lower than those of 7075 alloy. On the other hand, the elongation and reduction of area were extremely small compared to conventional aluminum alloys. The fatigue strength of Al-Li-alloys was superior to that of conventional Al, alloys in the region of long fatiaue life (more than 10^5 cycles). It is suggested that the excellent fatigue strength of AI-LI alloys is mainly due to their high resistance to crack initiation.2. The fatigue strength was decreased by the underaging and overaging process. This was due to the decrease in both crack initiation and growth resistances. The crack initiation and growth were controlled by the precipitation of delta '-Phase during aging.3. Fatigue strength in 3%NaCl solution is much lower than that in air for both Al-Li alloys and conventional AI alloys. The corrosion fatigue strength of AI-LI alloys is not influenced by aging condition, and it is better than that of AI alloys.4. The notch sensitivity of AI-LI alloys is less than that of conventional AI alloys, especially in 8090 alloy. Non-propagating crack was observed only in 8090 alloy with the highest stress concentrator, whose stress concentration factor is 8.18.

研究了两种铝锂 (Al-Li) 合金 2090 和 8090 在旋转弯曲下的广泛疲劳性能，预计将用于未来的飞机。结果与传统铝合金2024和7075进行了比较。得到的结果总结如下： 1． AI-LI合金的拉伸强度与2024合金大致相同，但低于7075合金。另一方面，与传统铝合金相比，伸长率和断面收缩率极小。在长疲劳寿命（超过 10^5 个循环）方面，铝锂合金的疲劳强度优于传统铝合金。结果表明，AI-LI合金优异的疲劳强度主要归因于其较高的抗裂纹萌生能力。2．疲劳强度因欠时效和过时效过程而降低。这是由于裂纹萌生和生长阻力均下降。时效过程中δ'相的析出控制了裂纹的萌生和扩展。 3．铝锂合金和传统铝合金在3%NaCl溶液中的疲劳强度远低于空气中的疲劳强度。 AI-LI合金的腐蚀疲劳强度不受时效条件影响，优于AI合金。4． AI-LI合金的缺口敏感性低于传统AI合金，特别是8090合金。仅在应力集中最高的8090合金中观察到非扩展裂纹，其应力集中系数为8.18。