Heat Quenching Fluids are the emulsion used as a refrigerant for the required physical properties, deformation, brightness, cleaning, and workability during heat quenching to give a robustness to a steel through a tempering. According to the purposes and characteristics, there are 3 types. The characteristics depend on the type of mineral oil(main element), viscosity, boiling point range, site stirring condition, oil temperature, and stability of functional additive.

Water Soluble Quenching Fluids prevent a tempering crack and equally cool down the tempered part. It is important to keep equal temperature distribution of surface and to cool down smoothly in a low temperature. They are mainly used for a steel material with low risk of fire and low cost.

RT Quenching Fluids are the type 1 heat quenching fluids providing the best cooling at 60-80℃, It is desirable to set the use temperature of 40-80℃. Hot material goes into the fluid so the top layer of fluid is locally heated and sometimes ignited so stirring will level the temperature providing equal quenching and preventing a local heating so that the fluid life cycle will not be reduced.

High Temp. Quenching Fluids are type 2 and 3 quenching fluids requiring the care conforming to the type 1. However, the type 2 is a hot bath quenching fluid with the use temperature of 100-160℃ while type 3 is used in 150-200℃ so the degradation, oxidation, and thermal polymerization are more serious than the type 1. So the use limit is reached due to the increased viscosity or remaining carbon instead of reduced cooling performance.

When the viscosity and remaining carbon are increased, the sticking is increased and cooling performance is decreased resulting in reduced quenching effect and risky local heating. Especially when the viscosity is over 30-40cSt at 150℃, it gets easily overheated requiring high attention.