Rancang Bangung Sistem Refrigerasi pada Media Supercooling untuk Surface Hardening

Abstract

In modern industry, metal heat treatment technology is increasingly in demand because it is more economical than changing chemical composition to obtain certain mechanical properties. This study conducted heat treatment on cigarette machine cutting knives made from AISI 4140 alloy steel by surface hardening method using supercooling cooling media. Surface hardening is done by heating the steel to 650°C, then rapidly cooled (quenching) in a salt solution or brine cooled by a refrigeration system to -15°C. The research method includes the design of a refrigeration system and experimental studies related to the heat treatment process. The test results show that heat treatment with 650°C heating and quenching at -15°C produces a hardness of 758 HV or equivalent to 62 HRC from normal hardness 36 HRC, the hardness standards for industrial knives. From the test results and analysis, it can be concluded that the designed refrigeration system is able to produce an effective supercooling cooling medium to assist the surface hardening process. This allows the use of cheaper alloy steel while still achieving high hardness, making it more economical without reducing material performance.