Simulation and validation of the laser cladding process with aid of embedded thermocouples

Single and multi track laser cladding thermal field associated to holes presence in the base material geometry, strongly influences temperature distribution. Starting from the single clad description, comparison of a 3-D finite element thermal model with and without holes have been compared to identify which are they main differences that distinguish them. Holes have been done in order to locate thermocouples as close as possible to the cladding. This strategy allows to acquire temperature information aimed to validate the numerical model. According with the state of the art, when same strategy is applied, no information of articles that take into account their presence has been found, consequently effects that they have on the thermal field has to be investigated in order to see whether they can be neglected in the geometry representation or not. in order to characterize temperature dependent thermo physics proprieties of both base and cladding material (respectively h13 and stellite 21) including also latent heat of fusion and phase transformation, data collecting has been done and described. This step has been requested because few information about thermo physics proprieties of these materials are available. As far as laser simulation is concerned, 3-d goldak heat source is used. Heat source dimensions have to match with molten pool ones. Width and depth are easily identifiable cutting the sample perpendicularly to laser direction and looking at its cross section whilst, length of the molten pool, is estimated combining pyrometer and thermographic camera information in an innovative way. Customized boundary conditions are studied specifically for convective and radiative losses, contact among surfaces. The model has been thus validated comparing temperatures results obtained through the simulation with information provided by thermocouples placed in analog points. The best set up of boundary condition and heat source which guarantee optimal match among simulation and experimental results in the single pass model has been applied to a multi track cladding. Also with this model, temperatures obtained from the simulation have been compared with real data provided by thermocouples.