CHARACTERISTICS OF AISI 420 STAINLESS STEEL MODIFIED BY COMBINING GAS NITRIDING AND CrN COATING

Abstract

AISI 420 stainless steel is widely used in applications where wear and corrosion resistance are required. However, the heat treatment and nitriding process can drastically reduce the corrosion resistance of this stainless steel. This article focuses on investigating the influence of steel substrate and gas nitriding efficiency at two temperatures of 520 oC and 550 oC on some properties of CrN coating. The experiments were carried out to evaluate the surface hardness, microstructure and phase composition of nitrided layers. The coating adhesion and load capacity of the coating were performed according to VDI 3198 standard. Electrochemical testing was performed in a solution of 3.5% NaCl and then using the Tafel method to determine the corrosion current and corrosion potential. The thickness of CrN and CrN/CrN coating was 1.6 μm and 3 μm, respectively. The study showed that the corrosion resistance of coatings fabricated through duplex technology was affected not only by the normal defects but also by the porosity on the nitrided surface. The corrosion resistance of multilayer duplex coating was improved compare with mono-layer duplex coating due to its ability to cover and reduce pores and pitting defects.

Duplex Treatment of AISI 420 Steel by RF-ICP Nitriding and CrAlN Coating Deposition: The Role of Nitriding Duration

“…The duplex treatment of AISI 420 stainless steel using the RF-ICP source for plasma nitriding has higher nitriding rates in comparison with other nitriding methods [39][40][41]. A nitrided layer (CL + DZ) with a total thickness of 33.1 µm can be obtained for 40 min at a relatively low nitriding temperature of 470 • C (Figure 12).…”

Surface modification of AISI-420 steel by cathodic cage plasma niobium nitride deposition

“…1,2 Among these, martensitic SSs, including AISI-420 grade, are applied in glass moulding, moulds for plastic injection, structural parts, cutting tools, automatic components, and dental and surgical instruments. 3 The effective use of steel in these applications demands high strength and exceptional wear resistance, which can be obtained by surface processing. Several techniques can improve surface properties, such as thermochemical diffusion, hard coating deposition, or their combination.…”