SurfacemodificationofAISI316stainlesssteelbylasermeltingwasinvestigatedexperimentallyusing
2 and4kWlaserpoweremittedfromacontinuouswaveCO2 laser atdifferentspecimenscanningspeeds
ranged from300to1500mm/min.Also,aninvestigationisreportedoftheintroductionofcarbonintothe
same materialbymeansoflasersurfacealloying,whichinvolvespre-coatingthespecimensurfaceswith
graphitepowderfollowedbylasermelting.Theaimofthesetreatmentsistoenhancecorrosionresistance
by therapidsolidificationassociatedwithlasermeltingandalsotoincreasesurfacehardnesswithout
affectingthebulkpropertiesbyincreasingthecarbonconcentrationnearthesurface.Different
metallurgicaltechniquessuchasopticalmicroscopy,scanningelectronmicroscopy(SEM),andX-ray
diffraction(XRD)wereusedtocharacterizethemicrostructureofthetreatedzone.Themicrostructuresof
the lasermeltedzonesexhibitedadendriticmorphologywithaveryfinescalewithaslightincreasein
hardnessfrom200to230Hv.However,thelaseralloyedsampleswithcarbonshowedmicrostructure
consistingof g dendritesurroundedbyanetworkofeutecticstructures(g+carbide).Asignificantincrease
in hardnessfrom200to500Hvisobtained.Corrosionresistancewasimprovedafterlasermelting,
especiallyinthesamplesprocessedathighlaserpower