Charpy impact toughness and prior ß-grain size in TI6AL4V manufactured by high speed, high-power (3KW) laser powder bed fusion

Abstract

The build rate of a laser powder bed fusion machine can be increased by increasing the laser power. The current paper shows that the use of higher laser power results in a positive change in impact toughness of Ti6Al4V. Laser powder bed fusion is an additive manufacturing technique that can produce functional metal components. The use of higher laser power is accompanied by an increase in scan speed. Furthermore, a higher scan speed results in a faster solidification rate. During processing of Ti6Al4V prior ß-grain size is proportional to solidification rate. In this study prior ß-grain size of Ti6Al4V produced by high power laser powder bed fusion is compared to Ti6Al4V processed by conventional low power machines. The sub-size (55x10x2.5mm) Charpy impact toughness of Ti6Al4V produced in this study was measured to be 8-10J which is higher than the 6J measured for Ti6Al4V produced by low power laser powder bed fusion. This difference is discussed by comparing prior ß-grain size of the two materials.