Analysis of Nitride Layers on ARMCO Pure Iron: The Powder-Pack Nitriding Process

Abstract

The nitriding of iron and steel is of considerable technological importance, because it can make a pronounced improvement in the fatigue, the wear, and the corrosion resistance of these materials. Nitriding on the surface of ferrous alloys results in the formation of a compound layer of γ´-Fe4N1-x and ɛ-Fe3N nitrides or a mixture of γ´ and ɛ with a nitrogen diffusion zone beneath the nitride layer. The broad range of nitride layer properties needed for different applications requires good control of nitriding process [1-3]. In the powder-pack nitriding process, which is similar to the powder-pack carburizing process, samples are placed in an annealing box with a powder mixture that consists of nitrogen-rich material and an activator. The nitriding temperatures are between 723 K and 823 K, a range in which the nitriding potential is a function of the mount of activator used in the powder mixture. The powder-pack method is a low-cost process particularly suited for the formation of uniform nitride layers on structural alloy components with complex shapes and of various sizes [4-5]. In this study, the microstructure of the γ´-Fe4N1-x and ɛ-Fe3N layers formed on an ARMCO pure iron surface have been investigated at different temperatures by the powder-pack process.

Effect of thermochemical treatments on the surface hardening of a circular saw blade: A microstructure comparison of nitride layers, boride layers and TiN coating formed on ASTM A1011 steel

“…Cost of tool is also not negligible. A proposed solution consist of developing a hard, dense, wear-and corrosion-resistant coating formed on a surface with certain affinity in fracture toughness, as well as the creation of a dislocation interface that prevents the propagation of the corrosive medium to the substrate and the propagation of micro-cracks [1][2][3][4][5][6][7][8][9][10][11][12]. In particular, nitriding of tool surfaces is one of the most commonly used types of heat treatment of tool steels.…”

Recycling of the Powder-pack Boriding Mixture: Microstructural Characterization of Fe2B Layers on ASTM A36 Steel

“…These phases consist of orthorhombic and tetragonal lattices (body-centered) respectively. One basic advantage of boride layers is that they can reach high hardness values (between 1800-2000 HV), kept at high temperatures [1][2][3][4][5][6][7][8]. In the present study, the microstructure of the single phase layer (Fe2B) and the recycling of the powder-pack boriding mixture until it is no longer possible to form any layers on the surface of the ASTM A36 borided steel have been investigated at 1173 K with exposure time of 2 h by dehydrated paste-pack method.…”

Wear Properties of TiN Coating on AISI M2

“…Application of hard coatings to improve the resistance of tooling to withstand adhesive and abrasive wear underwent a significant development program within the past decades. Surface hardening treatments used in the metal-mechanic industry generally fall into two categories, diffusion (carburizing, nitriding, boriding, and carbo-boro-nitriding) and overlay coating (TiN) [1][2][3][4][5][6]. A hard layer on a soft surface can reduce friction and wear by preventing fissuring at both the macro and the micro-level.…”