Laser melting deposition of a porosity-free alloy steel by application of high oxygen-containing powders mixed with Cr particles

Abstract Laser melting deposition (LMD) of an alloy steel by application of commercial 12CrNi2 powder with O content as high as 0.53 wt% has been investigated. It shows that the LMD alloy steel contains micron-sized pores. The pore formation, which is assumed to result from gas bubbles due to the reaction of carbon and oxygen in the laser molten pool, can be prevented by mixing the alloy steel powder with an appropriate amount of Cr particles. The result is interpreted based on reaction thermodynamics in the molten pool in combination with TEM observation of the microstructure of the LMDed alloy steel.