Preferred Orientation of Inconel 690 after Vibration Arc Oscillation Welding

Abstract

To evaluate the crystal growth characteristics of vibration welding, Inconel 690 alloy was welded when subjected to synchronous mechanical vibrations. This study employs arc oscillation welding along with vibrations to obtain structures with the preferred orientation. The results show that the surface normal orientation of grains in vibrationless weld was {420} preferentially, but they were {200}, {311} and {420} preferentially in vibration welding. The microstructure between the first and the second pass weldings illustrates that vibrations disconnect the dendrite growth from the first pass weld to the second. The most recent grains were formed without relating to the neighbouring grain. In the vibrationless weld, the grain orientation was either parallel or perpendicular to the orientation of the nearby grains. Hence, the grains subjected to vibration welding have three orientations, but only one when subjected to vibrationless welding. On the other hand, secondary dendrite arms were rarely observed during vibration welding, but dendrites with orientations parallel to the vibration could grow easily and strongly. This result illustrates that vertical vibration encourages vertical dendrite growth and restricts their horizontal growth.