ULTRA-LOW CARBON (ULC) STEEL MODIFIED BY TRIODE PLASMA NITRIDING AND PVD COATING - EFFECTS ON MICRO-STRUCTURE AND PROPERTIES

摘要

Ultra-low carbon (ULC) steels exhibit low yield strength and excellent formability. Plasma Assisted Physical Vapor Deposition (PAPVD) is a potential coating method for enhancing the strength at the surface of these steels. However, when deposited onto low strength alloys PAPVD coatings may undergo premature failure if the substrate plastically deforms under heavy load. Extra load support is usually required for hard coatings to perform satisfactorily. This work describes the characterization of Ti-stabilized ULC steels after surface modification by D.C Triode Plasma Nitriding (DC-TPN) and sequential coating with CrAIN by Electron Beam Plasma Assisted Physical Vapor Deposition (EB-PAPVD). Nitrided steel and duplex System were, respectively, 2.6 times and 3.5 times harder than the untreated Ti-ULC steel. Results indicate that it is feasible to manufacture duplex Ti-ULC steel via PAPVD, as significant improvements in mechanical properties were recorded for both nitrided and duplex-treated steels.