Heat Treatment Metallurgy: The Science Behind Blade Hardness

Heat treatment is the critical process that determines a blade's performance characteristics. Through controlled heating and cooling, we manipulate steel's crystalline structure to achieve the ideal balance of hardness and toughness.

Austenitization occurs at 1050-1095°C, depending on steel composition. At this temperature, carbon dissolves into the iron matrix, creating a uniform structure. Precise temperature control is essential—even 10°C variation affects final properties. We use computer-controlled furnaces with ±2°C accuracy.

Quenching rapidly cools the blade, trapping carbon in a supersaturated solution that creates martensite—the hardest steel structure. Quench medium selection affects cooling rate: oil provides moderate cooling suitable for high-carbon steels, while water or brine creates faster cooling for lower-carbon alloys.

Tempering reduces brittleness while maintaining hardness. Heating to 175-205°C allows controlled stress relief without sacrificing edge retention. Multiple tempering cycles—typically three—ensure uniform properties throughout the blade.

Cryogenic treatment at -196°C (liquid nitrogen temperature) converts retained austenite to martensite, increasing hardness by 1-2 HRC points while improving wear resistance. This additional step distinguishes premium blades from standard production.