Process characterisation of pulsed Nd:YAG laser seam welding

Nd:YAG laser seam welding is a new joining technology which is of much interest to the automotive industry, and the electric, and electronic industries. A simple but useful mechanism for the Nd:YAG laser seam welding process is developed. Laser seam welds were produced in 0.7 mm thick bare steel sheet in the lap-joint configuration. A wide range of pulsed laser welding parameters was identified. These include average peak power density (APPD), peak power, mean laser power, traverse speed pulse repetition rate, duty cycle, pulse energy, spot size, and pulse duration. The type of laser beam temporal pulse shape studied was a rectangular power pulse. The effects of pulsed laser welding parameters on heat flow, weld dimension, and weldability are investigated. The study shows that weld quality is principally affected by APPD, mean power, and traverse speed, of which APPD is the most critical process parameter. A processing map containing the APPD effects is constructed as a guide Sot producing good welds.