Cryogenic heat treatment

In case of steels, the benefits are usually attributed to the reduction or elimination of retained austenite from hardened steel and accompanied by the precipitation of small finely dispersed carbides (η-carbides) in the martensite. Figure 1 shows a typical cryogenic treatment temperature sequence for tool steels.

PRESENCE OF RETAINED AUSTENITE IN TOOL STEELS

Through hardening of steel involves heating the steel to a temperature at which it becomes austenite and then cooling rapidly enough to produce martensite, a hard and strong, but brittle structure. Tempering at moderately elevated temperatures reduces this brittleness. Generally austenite phase may be retained in small amounts in low-alloy steels and in appreciable amounts in high-alloy steels, because of the austenite stabilizing effect of various alloying elements. 

Performance of D2 & D3 and M2 & M6 grades cutting tools and metal forming tools were improved to 3 times to that of hardened and tempered.

 

 

 

During heat treating, steel’s microstructure transforms from austenite to martensite, which makes the steel much more wear resistant. However, some small pockets of austenite may not transform and this does not allow the knives to perform as well as they can. DEEP CRYOGENIC processing helps change retained austenite to martensite, completing the transformation process.

DEEP CRYOGENIC processing is different from conventional cryogenic processing and requires cooling the parts to more than 300° below zero compared to about 120° for conventional cryogenic processing. DEEP CRYOGENIC processing is a microprocessor controlled dry process, which includes cooling the parts at a programmed rate. Soaking the parts for up to thirty-six hours, and then an additional tempering operation to relieve any stress that may remain.

Our services are able to combine DEEP CRYOGENIC processing with state of the art VACUUM HEAT TREATING capability to offer unmatched metal treating and the best performance possible from your knives and tools.

Deep Cryogenic Processing offers the following benefits:

• ncreases abrasive wear resistance.
• Changes the knife’s entire structure, not just the surface. Subsequent refinishing operations or re-grinds do not affect the permanent improvements.
• Increases durability and wear life.
• Decreases brittleness.
• Increases tensile strength, toughness and stability coupled with the release of internal stresses.