1. Swift Transfer & Controlled Pre-cooling

Moving thin blades from the heating furnace to the cooling tank too slowly will cause the workpiece temperature to drop below the Ar3 critical point before it enters the quenching pool. This leads to partial decomposition, resulting in an improper quenched microstructure that fails to meet hardness requirements.

Rule of Thumb: Thin, small-sized blades must be transferred into the cooling pool as fast as possible, while larger blades require precise timing when pre-cooling.

2. Rational Furnace Loading

The furnace loading volume must be reasonable. The ideal spacing between blades should match the thickness of the blade itself. Overlapping workpieces will cause uneven heating, which directly leads to inconsistent hardness.

3. Proper Quenching Pool Spacing

When submerging blades into the quenching liquid, maintain a distinct distance between each piece. Packing them too tightly obstructs the rupture of the vapor blanket (steam film) near the workpieces, resulting in lower hardness on the surfaces facing each other.

4. Intermittent Quenching for Temperature Stability

Do not rush to quench the entire batch in one continuous run. Monitor the drop in furnace temperature; you must close the furnace door midway to reheat the chamber when necessary. This ensures that the workpieces quenched first and last achieve identical hardness.

5. Strict Cooling Liquid Temperature Control

Pay close attention to the temperature of the cooling fluid. Quenching oil must be maintained strictly between 30°C and 80°C. Operating outside this range will result in insufficient or uneven hardness across the batch.