Laser melting of alumina-coated steel

Laser melting of alumina-coated steel surface is considered. Temperature field and phase change in the alumina coating and steel are predicted numerically using the control volume approach. The repetitive laser pulses with 60% duty cycle are incorporated in the analysis. The porosity-enthalpy method is adapted to account for the phase change. It is found that steel at alumina coating interface undergoes a melting before alumina after the end of heating of the 2nd pulse. The melt pool size of alumina is smaller than that corresponding to steel. The resolidification of the melt pool takes place in the alumina coating, whereas the melt pool remains in steel beneath the alumina coating during the cooling cycle.