Solidification behaviour in plasma are welding

Melting and solidification behaviour in the deep penetration welding proces s is different from that in conventional welding processes. In deep penetra tion processes, there is keyhole formation and the full thickness of the pl ate receives the are heat input unlike in conventional processes in which t he heat input is received only by the surface nodes. In the present study, the thermal analysis of molten pool formation and solidification for keyhol e welding using plasma are welding has been done using the finite element m ethod. The model accounts for the several phenomena associated with welding , like the distributed are hear input over the top surface and along the th ickness, the temperature-dependent material properties, convection and radi ation heat losses etc. The analysis is performed for different combinations of parameters, viz. welding current and welding speed, which have the maxi mum influence on molten pool shape and solidification behaviour. The model has also been validated by conducting experimental measurement of thermal c ycles experienced by the plate for different welding parameters. The weld p ool dimensions, viz. the length and width are found to increase with increa sing current and decreasing welding speed. Thermal cycles at locations clos e to the weld reach a higher value of temperature and the time for peak tem perature is also less but at farther locations, the peak temperature reache d is lower and the time for peak temperature is higher. Details of the mode l, the experimental results obtained and the solidification characteristics of the pool are discussed in this paper.