AISI 4140 steel is steel containing 0.98% chromium, 0.42% carbon,
this shows that AISI 4140 steel is a low alloy steel. This steel is also suitable
for the heat treatment process which can increase the hardness of the steel.
This study aims to determine the effect of the heat treatment process media
on changes in microstructure and thermal conductivity of AISI 4140 steel.
The process of making specimens, steel cut 4mm thick and 2mm with
a diameter of 40 mm by 4 pieces then treated with a temperature of 850 ° C
for 30 minutes and cooled using air, water and oil cooling media. After the
heat treatment process the steel is then tested for microstructure and thermal
conductivity test.
The results of the study show that changes in the microstructure affect
the thermal conductivity value of AISI 4140 steel. AISI 4140 steel which is
heat treated using oil coolers has large granules and has good conductivity
values. whereas steel which is cooled by using air has small granules and low
conductivity.
Keywords: "AISI 4140, heat treatment,micro structure, thermal conductivity
