Larger-area alloying of CSiB+NiMoCo on carbon steel by a 45-kW CO2 laser: effect of protection gas on process and microstructure

摘要

Abstract: Laser alloying of CSiB$PLU@NiMoCo by a 45kW CO$-2$/ laser was investigated to achieve sound large functional layer with smooth surface, little oxidation and free of cracks on cheap and broadly used common carbon steel XC38. The protection gas has obvious influence on the alloying results. Compared with Ar and N$-2$/, He results in the best surface smooth, finest microstructure (second dendrite arm Ar:N$-2$/:He equals 1:1:0.6), highest cooling rate (Ar:N$-2$/:He equals 1:1.1:4),highest average hardness HV0.2(Ar:N$-2$/:He equals 1:1.14:1.15), most resolvability of alloying elements (about Ar:N$-2$/:He equals 1:1.1:1.5). These results can be properly explained by mainly the difference in physical properties of these three gases. !8