What is Cryogenic Treatment (Ultra Sub-Zero Treatment)?
Cryogenic treatment—also referred to as ultra sub-zero treatment—is an advanced thermal process that involves cooling steel to extremely low temperatures, typically below -100°C, using materials such as carbon dioxide or liquid nitrogen. This technique is performed after the quenching phase of heat treatment and plays a crucial role in elevating the steel's structural stability and performance.
During standard quenching, steel undergoes a transformation from austenite, a soft, high-temperature phase, to martensite, a hard and brittle structure. However, a portion of austenite—ranging from 10% to 40%—often remains untransformed within the steel. This residual austenite can lead to dimensional distortion, decreased hardness, and long-term structural instability.
Cryogenic treatment accelerates the transformation of residual austenite into martensite by exposing the steel to ultra-low temperatures. This results in a finer, more uniform crystalline structure, improved hardness, enhanced wear resistance, and greater dimensional stability. For this reason, cryogenic treatment is widely used in the production of high-precision tools, molds, and cutting instruments.
In recent years, its application has expanded beyond industrial fields to include consumer goods such as high-end audio equipment, musical instruments, sports gear, and more—demonstrating its effectiveness in improving material performance across various industries.
At KAKINUMA, we incorporate ultra sub-zero treatment into our knife-making process to ensure each blade achieves the highest standards of precision, durability, and refinement—reflecting the uncompromising craftsmanship that defines our brand.