Laser-aided direct metal deposition of CO-285

Abstract

In this work, Co-285 superalloy coatings on 1018 mild steel substrates were fabricated by laser-aided-direct-metal-deposition (LADMD) process. The microstructure, elements distribution, microhardness distribution and the phases of the coatings were investigated using optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS), microhardness testing and X-ray diffraction (XRD). Results indicate that the coatings had dense, pore-free and homogeneous structures, as well as a metallurgical combination with the steel substrates. The best combination of parameters was: laser power 800W, powder flow rate 8.6g/min and scanning speed 37.5cm/min. The microhardness of the coating was 420HV0.5, which was almost 1.93 times of that of the 1018 mild steel (218 HV0.5). The XRD analysis indicates the existence of α-Co (Co-rich matrix phase), Cr23C6 and Co3W in the coating. Sliding wear tests showed that the seizure and oxidation tendencies, and abrasive wear of the large-area crack-free Co-285 coating were much more suppressed, resulting in the improvement of wear properties.In this work, Co-285 superalloy coatings on 1018 mild steel substrates were fabricated by laser-aided-direct-metal-deposition (LADMD) process. The microstructure, elements distribution, microhardness distribution and the phases of the coatings were investigated using optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS), microhardness testing and X-ray diffraction (XRD). Results indicate that the coatings had dense, pore-free and homogeneous structures, as well as a metallurgical combination with the steel substrates. The best combination of parameters was: laser power 800W, powder flow rate 8.6g/min and scanning speed 37.5cm/min. The microhardness of the coating was 420HV0.5, which was almost 1.93 times of that of the 1018 mild steel (218 HV0.5). The XRD analysis indicates the existence of α-Co (Co-rich matrix phase), Cr23C6 and Co3W in the coating. Sliding wear tests showed that the seizure and oxidation tendencies, and abrasive wear of the large-are...