They acquired different cooling
parameters changing the water flow and cooling time in cooling
media. While a hardness of 53 HRC (Rockwell C Hardness) was observed
on the surface as a result of quenching for 2 min 15 s in
pressure water, the air–water mixture used for quenching for 10
and 20 min caused respectively 55 and 57 HRC hardness on the
surface of the sample.