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Heat Treat Tips: Aqueous Quenchant Selection Tips

Determine your quench: Induction or Immersion? Different aqueous quenchants will provide either faster or slower cooling depending upon induction or immersion quenching applications. It is important to select the proper quenchant to meet required metallurgical properties for the application.


1. Part material: Chemistry and hardenability are important for the critical cooling rate for the application.

2. Part material: Minimum and maximum section thickness is required to select the proper aqueous quenchant and concentration.

3. Select the correct aqueous quenchant for the application as there are different chemistries. Choosing the correct aqueous quenchant will provide the required metallurgical properties.

4. Review selected aqueous quenchant for physical characteristics and cooling curve data at respective concentrations.

5. Filtration is important for aqueous quenchants to keep the solution as clean as possible.

6. Check concentration of aqueous quenchant via kinematic viscosity, refractometer, or Greenlight Unit. Concentration should be monitored on a regular basis to ensure the quenchant’s heat extraction capabilities.

7. Check for contamination (hydraulic oil, etc.) which can have an adverse effect on the products cooling curves and possibly affect metallurgical properties.

8. Check pH to ensure proper corrosion protection on parts and equipment.

9. Check microbiologicals which can foul the aqueous quenchant causing unpleasant odors in the quench tank and working environment. If necessary utilize a biostable aqueous quenchant.

10. Implement a proactive maintenance program from your supplier.