Melt pool temperature and its effect on clad formation in pulsed Nd:yttrium-aluminum-garnet laser cladding of Stellite 6

The effective melt pool temperature in pulsed Nd:yttrium-aluminum-garnet laser cladding of Stellite 6 was measured with a two-color pyrometer. The pulse peak temperature (Tp) and durations when the melt pool temperature is above the melting point of Stellite 6 powder (t1) and substrate (t2) in each pulse have been calculated and averaged. The effects of laser operating parameters (pulse energy, pulse frequency, spot overlap, powder mass flow rate, and pulse length) on these values have been investigated. It is found that Tp depends on the peak laser power, pulse length and determines the maximum size of melt pool (DM), whereas both t1 and t2 increase with peak power, pulse frequency (f), pulse length, and spot overlap. The prediction of the clad area, the total area of a single-track clad layer, based on Tp, t1, and t2 is given for pulsed laser cladding of Stellite 6. Comparison between the experimental data and prediction has been made with a correlation coefficient of 0.99. In order to produce a larger single-track clad area, the higher value of the product of f·t1 and longer beam interaction time (tau) are required