Abstract: The convection patterns were observed in laser cladding layer of FeCrSiB alloy.Laser beam symmetry, dilution of cladding layer from substrate,etc.With relation to con- vection patterns have been investigated.Macro-segregation and macroalloying in the cladding layer were found to be resulted from convection.The dilution rates of substrate materials into cladding layer are directly influential in microstructure and performace of the cladding.Ideal laser cladding conditions require that there is a minimum of dilution.

Key words: laser cladding, convection, mass transfer, Fe-Cr-Si-B, alloy