The effects of energizer and carburizing temperature and time on mechanical properties of hardened big knives in the pack carburizing process

Abstract

The purpose of this research is to study the effects of energizer and carburizing temperature and time on the mechanical properties of hardened big knives in the pack carburizing process. The mechanical properties of carburized and hardened big knives were compared to those of commercial hardened big knives made from leaf-spring steel that were forged, ground and quenched following the traditional forging processes. The experiment was conducted by forging big knives made of low carbon steel (grade AISI 1010). The first group of them was then pack-carburized using 10% by weight of calcium carbonate with 90% by weight of eucalyptus charcoal. The second group used 10% by weight of egg shell with 90% by weight of eucalyptus charcoal. The carburizing temperatures were 900, 950 and 1,000°C, with carburizing times of 30, 60 and 90 minutes followed by air cooling. The austenitizing temperature was 780°C with a holding time of 20 minutes, followed by quenching in water. Finally, the big knives were tempered at 180°C for 1 hour. Micro-Vickers hardness testing, impact testing and microstructure inspection were carried out. The results of this experiment show that the hardness of hardened big knives increased with an increase in the carburizing temperature and time. In contrast, the impact value of carburized steel decreased with an increase in the carburizing temperature and time. The hardness derived from using CaCO3 is slightly harder than that from using egg shell, however, the impact energy is higher when using egg shell, compared to using CaCO3.

Keywords

• Pack carburizing
• Calcium carbonate
• Egg shell
• Carburizing temperature
• Hardened big knives