Abstract:
SUS 630 Steel hardness is 30.9 HRC and Chromium content is 12%, based on its
use at PT. Pupuk Kalimantan Timur recommended a hardness of 55 HRC, to
increase material hardness can be done by means of material engineering, namely
Hardening. The aim of the study was to determine the effect of variations in
holding time and cooling media on the hardness and microstructure of steel sus
630. The hardening process was carried out to reach 1020
0
C then holding time
with variations of 10, 20, 30, 40, and 50 minutes then dipped into water , salt
water, and oil to room temperature. Microstructure was tested using an optical
microscope with 400x magnification and hardness using Rockwell C hardness
with a load of 150 kg. The observation of the microstructure after hardening of the
structure formed is the martenstie lath, residual austenite, and metal carbide. The
hardness test results were highest in water cooling media (34.2 HRC), salt water
(34.2 HRC), and oil (34.1 HRC) and raw material (30.9 HRC). From this study it
can be concluded that the hardening process can increase the value of violence.
