Structural Changes of Nitrogen Ferrite After Aging in Temperature Interval up to 100 °С

Abstract

This paper aims to determine the extent of aging of nitrogen ferrite at temperatures below 100 °C and the structural and strength changes that occur in the process. The tests are carried out on samples of technically pure iron (Armco). The specimens are pre-deformed by tension and re-crystallisation heating to achieve a large-grain ferrite structure. A large-grained structure has been chosen to more accurately track the change in micro-hardness of the individual grains during the aging process. Nitric ferrite results from gas carbonitriding and subsequent hardening. Upon hardening, the samples are stored in a refrigerator, and then the surface layer formed is removed through electrochemical corrosion. Afterwards, aging heat treatment at temperatures below 100 °C is undertaken. After the aging process, micro-hardness of the individual grains is examined and X-ray structural analysis is performed.

Keywords

• nitric ferrite
• aging
• gas carbonitriding
• micro-hardness
• X-ray structural analysis