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Heat Treatments and Surface Hardening of Small Weapon Components
Published in Jose Martin Herrera Ramirez, Luis Adrian Zuñiga Aviles, Designing Small Weapons, 2022
Jose Martin Herrera Ramirez, Luis Adrian Zuñiga Aviles
Carbonitriding is a process in which carbon and nitrogen are supplied to the surface of a steel workpiece to form a hard case. The process is a modified form of gas carburizing, in which ammonia is introduced into the gas-carburizing atmosphere. As in gas nitriding, elemental nitrogen forms at the workpiece surface and diffuses along with carbon into the steel. Carbonitriding takes place at a lower temperature and a shorter time than in gas carburizing, producing a lower case depth. The process consists of heating the workpiece above the A1 temperature (Figure 8.1), except in the case of ferritic nitrocarburizing, which is carried out below A1. After a sufficient soaking time, a quenching is performed, which is typically made in oil for minimizing distortion.
Microstructural Characteristics of Metals
Published in Vladimir B. Ginzburg, Metallurgical Design of Flat Rolled Steels, 2020
Case hardening - This is the process that involves a change in the chemical composition of the surface portion of a workpiece. Variations of this process such as carburizing, nitriding, and carbonitriding can be utilized as follows: Carburizing produces a high-carbon layer at the surface of low-carbon steel by heating it in contact with either carbonaceous solid material or in a carbon-rich liquid (liquid carburizing) with subsequent quenching. Depending on the process, the heating temperature varies from 870°C to 1050°C (1600°F to 1920°F).Nitriding introduces nitrogen into the surface layer of a solid ferrous alloy by holding it in contact with nitrogen material. For ferritic steel, the holding temperature is below the Ac1 temperature and quenching is not usually required. The gas-phase nitronization treatment is known as bright annealing.Carbonitriding combines both carburizing and nitriding processes.
The surface hardening of steels
Published in William Bolton, R.A. Higgins, Materials for Engineers and Technicians, 2020
Carbonitriding is a surface-hardening process which makes use of a mixture of hydrocarbons and ammonia. It is therefore a gas treatment and is sometimes known as dry-cyaniding – a reference to the fact that a mixed carbide-nitride case is produced, as in ordinary liquid-bath cyanide processes (see Section 14.2.2).
High-cycle fatigue and surface layer stability of case-hardened PM-steels with graded porosity
Published in Powder Metallurgy, 2021
James M. Damon, Erik Jung, Michael Zürn, Stefan Dietrich, Volker Schulze
The main aspect of carbonitriding is the gradient in elemental composition and the resulting surface hardness and compressive residual stress after quenching. In the following Figure 4, the carbon and nitrogen depth profiles in dependence of density of Fe–0.85Mo are shown. In the following plots, labels are according to their density (6.9 g/cm3 7,2 and 7.35 g/cm3). There are identical element contents in the densified areas close to the surface, with deviations of core carbon contents in depths above 0.5 mm. While the carbon content in the core is levelling at 0.38 wt-% for the lowest density, the carbon content significantly reduces for the highest density down to 0.28 wt-%.