Effects of pulse duration and overlapping factor on melting ratio in preplaced pulsed Nd:YAG laser cladding

Melting ratio is known as a suitable factor to illustrate the effects of process parameters on the clad profile in order to provide a proper process design. However, the definition of melting ratio based on continuous irradiation of energy does not accommodate for pulse parameters. Hence, in order to study the effects of pulse parameters, such as pulse duration and overlapping factor, the definition of melting ratio is restated for pulsed laser process based on energy density concept. Carbon steel was cladded with Stellite 6 by scanning a 400 W pulsed Nd:YAG laser over a preplaced layer of powder paste. The results show that the trends of clad profiles variations can be explained using the restated definition. The results also show two different ranges for the effects of pulse duration and overlapping factor on melting ratio.

► The melting ratio definition is restated for pulsed laser process.
► When overlap factor increases, melting ratio decreases first and then increases.
► When pulse duration increases, melting ratio increases first and then decreases.
► The trends of melting ratio variations and clad volume variations are in agreement.