Surface characteristics analysis of nitrocarburized (Tenifer) and carbonitrided industrial steel AISI 02 types

Abstract

Generally, tool steels for cold work are obtained by rolling and forging processes. They are treated to have a structure conferring to the material a high toughness limit in terms of wear resistance and endurance. The objective of this study is the thermochemical heat treatment of industrial steel blades made of AISI 02 types, intended for polymer crushing. The effects of nitrocarburizing (Tenifer) and gaseous carbonitriding processes on surface characteristics are considered. These surface treatments increase the usefulness of properties, that is, fatigue strength, wear and corrosion resistance of this microalloyed steel. The influence of treatment duration and the thickness of the layers on surface properties are investigated. The analysis and characterization are carried out using physical analysis [optical microscopy, scanning electron microscopy, X-ray diffraction and glow discharge optical emission spectroscopy (GDOES) techniques] and mechanical measurements (microhardness, weight loss and residual stresses) of treated material. The results are intended to contribute in defining and optimizing the adequate choice of treatments for this type of steel in industrial conditions.

Post‐oxidizing effects on surface characteristics of salt bath nitrocarburized AISI 02 tool steel type

“…For the effect of nitrocarburizing time, the N8 sample presents a Fe 3 N peak smaller than that of N6. [18] It is the same for sample N6O90 when compared to N8O90. The consideration of the combination of oxidation and nitrocarburizing times applies for the N8 sample which presents a Fe 3 N peak almost the same as that of N8O30 but larger than that of N8O90.…”

“…Abrasive wear tests were conducted by means of a pin-ondisc setup [18,21] and the pin-shaped specimens were forced to slide on fresh 800-mesh abrasive paper with an applied normal load of 2 N. The paper was fitted on a steel disc rotating at a speed of 14 cycles/min. This low angular speed is adjusted in order to establish the relative wear behaviour of the different phases at the immediate surface layers.…”

“…[17] Additionally, thermochemical treatments such as nitrocarburizing in salt bath for 6 h have been successfully introduced to improve the surface characteristics. [18] In the present research, an investigation is carried out in order to provide improvements of corrosion, wear and strength resistance. Results of surface modifications after using salt bath nitrocarburizing for 6 h and 8 h at 570…”

Effects of gas carbonitriding process on surface characteristics of new hot working tool steel

“…When processing times are very long, high levels of retained austenite and case porosity may occur. 6 Formed cases can be harder than carburised cases, and they allow maintaining an appreciable hardness at higher service temperatures. Usually, quenching conditions will determine final characteristics, such as surface hardness, the type and properties of induced internal stresses and mechanical properties, such as torsional and tensile strengths.…”

Carbonitrieren von Warmarbeitsstählen*

“…Da diese Stähle einen hohen Anteil an Nitrid bildenden Legierungselementen aufweisen, findet zusätzlich zur martensitischen Härtung beim Abkühlen eine Ausscheidungshärtung statt, da sich beim Carbonitrieren durch die zusätzliche Diffusion von Stickstoff in die Randschicht bei Überschreitung der Löslich-keit Legierungselement-Ausscheidungen, wie Nitride und Carbonitride, ausbilden können. Untersuchungen von Fares belegen, dass durch Carbonitrieren die Verschleißbeständigkeit des Kaltarbeitstahls 1.2842 verbessert werden kann [4]. Für Warmarbeitsstähle liegen bisher nur wenige Untersuchungen zum Carbonitrieren vor, z.…”