EFFECT OF NI CONTENT ON CRACKING SUSCEPTIBILITY AND MICROSTRUCTURE OFLASER-CLAD FE-CR-NI-B-SI ALLOY

An investigation is reported of the laser surface cladding of self-flu xing Fe-Cr-Ni-B-Si alloys on a medium carbon steel substrate using the preplaced powder method. The cracking susceptibility and microstructu re of the laser-cladding layer have been studied in terms of its Ni co ntent, thermal expansion coefficient and wettability on the substrate. With increasing Ni content the cracking susceptibility of the claddin g layer decreases and its microstructure changes from a ''bamboo leaf' ' structure to a typical dendritic one.