Joint characteristics of dissimilar materials friction welds. 2: In the case of titanium/aluminium welds

Abstract

The dominant factors determining the joint characteristics (strength, ductility and so on) in titanium and aluminum friction welds were investigated variously from the mechanical and metallurgical points of view. The mechanical factors were not the main factors determining the characteristics of the joints, as residual stress and plastic strain generated by the friction welding were not so large. It was found that the main factors dominating the characteristics of the joint were the metallurgical, that is the thickness of the intermetallic compound layer produced at the interface. The critical thickness of the intermetallic compound layer was about 5 micrometers. When this kind of the joint is used in a high temperature environment, the working temperature and time should be sufficiently noted. When the working time became long the characteristics of the joints were largely decreased as the thickness of the intermetallic compound layer increased.

機械的および金属学的観点からチタンおよびアルミニウムの摩擦接合における接合特性(強度、延性およびその他)を決定づける支配的な要因について種々調査した。摩擦接合によって発生する残留応力および塑性歪みはあまり大きくないので、機械的要因は接合部の特性を決める主要な要因ではない。接合部の特性を決める主な要因は金属学的なもので、これは界面で生成される金属間化合物層の厚さである。金属間化合物層の臨界厚さは約5マイクロメートルである。この種の接合部が高温度の環境で使用されると、使用温度および時間を十分に注目すべきである。使用時間が長くなると、金属間化合物の厚さが増加するので接合部の特性が大きく低下する。