Welding and forming of thick steel plates with a high power density diode laser

Diode lasers offer the advantage of higher conversion efficiency than conventional CO₂ and YAG lasers, but their beam properties are very poor. Nevertheless, they can be focused into a spot 0.96mm in diameter at a laser power of 2kW. The feasibility was thus examined of welding and forming thick steel plates using a diode laser with a high power of 2kW and a high power density of 236kW/cm². Steel plates ranging from 0.5mm to 10mm in thickness were successfully welded without porosities or cracks. The diode laser beam’s top hat shape was found to be suitable for welding. Laser forming of thick steel plates with a high power density diode laser was also investigated. A 5mm thick steel plate was bent at an angle of about 9.23° by scanning it 50 times with a 4mm diameter beam at a power of 1kW and a scanning speed of 1.5m/min. Even though the diode laser has a short focusing length, it was found to be suitable for laser forming because it does not require the melting of specimen’s surface.