Single crystalline-like crystallographic texture formation of pure tungsten through laser powder bed fusion
Tsubasa Todo, Takuya Ishimoto, Ozkan Gokcekaya, Jongyeong Oh, Takayoshi Nakano
Abstract
We successfully formed the first prominent crystallographic texture of tungsten using laser powder bed fusion (LPBF). It is difficult even to manufacture highly dense tungsten products using LPBF because of its extremely high melting point and high thermal conductivity. By tuning the laser process parameters, we succeeded in fabricating almost fully dense pure tungsten parts with a relative density of 99.1%, which is the highest value yet to be reported. More importantly, a single crystalline-like prominent crystallographic texture evolved, in which <011> preferentially oriented in the scanning direction. This texture was formed to reduce the crystal misorientation at the melt pool center, at which the solidification fronts from the right and left halves of the melt pool encounter. This texture formation mechanism is similar to that of conventional alloys with ordinary thermal properties; however, the crystal growth directionality that governs the crystallographic orientation differs according to the melt pool morphology.