Details

Autor(en) / Beteiligte

• Cunningham, Ross
• Zhao, Cang
• Parab, Niranjan
• Kantzos, Christopher
• Pauza, Joseph
• Fezzaa, Kamel
• Sun, Tao
• Rollett, Anthony D

Titel

Keyhole threshold and morphology in laser melting revealed by ultrahigh-speed x-ray imaging

Ist Teil von

• Science (American Association for the Advancement of Science), 2019-02, Vol.363 (6429), p.849-852

Ort / Verlag

United States: The American Association for the Advancement of Science

Erscheinungsjahr

2019

Quelle

American Association for the Advancement of Science

Beschreibungen/Notizen

• We used ultrahigh-speed synchrotron x-ray imaging to quantify the phenomenon of vapor depressions (also known as keyholes) during laser melting of metals as practiced in additive manufacturing. Although expected from welding and inferred from postmortem cross sections of fusion zones, the direct visualization of the keyhole morphology and dynamics with high-energy x-rays shows that (i) keyholes are present across the range of power and scanning velocity used in laser powder bed fusion; (ii) there is a well-defined threshold from conduction mode to keyhole based on laser power density; and (iii) the transition follows the sequence of vaporization, depression of the liquid surface, instability, and then deep keyhole formation. These and other aspects provide a physical basis for three-dimensional printing in laser powder bed machines.