What Is Deep Cryogenic Treatment?

How is deep cryogenic treatment different from "cryogenic treatment" or sub-zero treatment?

Depth of cold. Conventional sub-zero (or "shallow cryogenic") treatment in heat-treat shops reaches roughly −120 °F, cold enough to convert much of the retained austenite. Deep cryogenic treatment goes to −300 °F and holds there — driving that conversion further and adding a second effect, lower residual stress and fine carbide precipitation.

What actually changes inside the metal?

It depends on the alloy class, and an honest answer says so. In hardened, carburized, and tool steels: retained austenite converts to martensite, fine η-carbides precipitate, grain size reduces and the temper relieves the transformation stresses in the fresh martensite. In austenitic manganese steel — most mining crusher and GET castings — the retained austenite mechanism does not apply but TRIP/TWIP enhance the work hardening characteristics and residual stress is reduced.

None of this is a coating. The change happens through the entire cross-section, which is why the effect survives regrinds and resharpening, and why a treated crusher liner is still a treated liner at the end of its service life.

For the metallurgist. In martensitic steel, the martensite-finish temperature sits below room temperature, so a fraction of austenite survives oil or water quenching; holding at −300 °F drives that transformation further — a well-established beneficial effect, measurable as lower retained-austenite percent by X-ray diffraction before and after. Fine η-carbide precipitation during the subsequent temper is clearly seen in microscopy though DCI's co-authored 2026 study in Scientific Reports shows compressive-stress-enhanced carbide precipitation in deep cryogenically treated martensitic steel for shovel teeth; the literature is equally candid that magnitude depends on chemistry, prior heat treatment, soak temperature, and hold time, which is why DCI runs a recipe per alloy rather than one cycle for everything. Hadfield 13–22% Mn steel is engineered to stay austenitic and to work-harden under impact (TRIP/TWIP); DCI's program there is field tested and empirical — treated and untreated castings compared under an NRC-IRAP project with Innotech Alberta, TRIP/TWIP work-hardening studied with the University of Alberta, with SEM/EBSD analysis under an NSBI grant, improved wear resistance measured in treated castings by mining companies, and a co-authored 2026 paper in Metallurgical and Materials Transactions A on twinning-assisted toughening of high-manganese steels after deep cryogenic treatment — with the mining results as the operating evidence. High-chrome white iron sits between the two: an austenitic or martensitic matrix, depending on heat treatment, around a hard chromium-carbide network. There, DCT works largely through precipitation of chromium carbides in the matrix, a reduction in retained austenite, and suppressed micro-crack nucleation at carbide boundaries.

What does the treatment cycle look like?

One continuous, computer-controlled run of about 72 hours end to end: a slow descent in dry nitrogen vapor (parts never touch liquid nitrogen), an extended soak near −300 °F, and an in-chamber tempering up to +200 °F — recorded throughout, so every job has its unbroken temperature log.

The nitrogen itself is the process's only consumable — nitrogen is 78% of air, and after the cycle it simply returns to the atmosphere, which is why DCI trademarked the phrase infinitely renewable and infinitely recyclable™.

Which metals respond best?

Hardened, high-carbon tool steels, white iron and manganese steels respond most strongly — the alloys used in mining wear castings (13–22% manganese, high-chrome white iron, high-carbon alloy), dies and tooling, gears, and bearings. Soft, low-carbon, or pearlitic parts generally see little benefit, and an honest provider will tell you so before treating them.

The practical screen is the failure mode as much as the alloy. Parts that fail from high-stress or gouging abrasion, impact, adhesive wear, or contact fatigue are candidates; parts that fail from overload, poor fit-up, or corrosion-driven mechanisms are not, whatever their chemistry.

How is a result measured?

Two ways, and both matter. In the metal: retained-austenite percent by X-ray diffraction, residual stress by XRD (ASTM E2860), hardness (HRC / HBW), and ASTM G81 gouging-abrasion mass loss — all repeatable by any third-party lab. In service: the operation's own metric — hours or tons to changeout, wear rate at each inspection — against a control set. The trial protocol →

Does it change the part's dimensions or hardness spec?

No. Treated parts keep their dimensions, their fit, and their installation — nothing is added to the surface and nothing is machined away. Bulk hardness typically changes little; what changes is wear behavior, driven by the converted microstructure and carbide population, which is why verification uses wear data and XRD rather than a hardness number alone.

Is the effect permanent?

Yes. The microstructural changes are permanent and extend through the entire cross-section. One treatment, before the part enters service, lasts the life of the part.

Where did deep cryogenic treatment come from?

Cold treatments have been used in metallurgy for decades, but industrial-scale deep cryogenic treatment is recent. DCI's chief technologist Jack Cahn has applied DCT since 1999 — first on machine-shop tooling for aerospace work, later developing test procedures used on JPL's Mars Exploration Rover program, and working with NIST's cryogenic processing lab. DCI has since built the validation layer the field lacked: an issued patent on validating treated articles (U.S. 9,721,258), draft engineering standards, and a USPTO-registered certification mark. The full history →

Related: Does cryogenic treatment actually work? The evidence and the limits
Related: What does treatment cost? · FAQ · How we verify results

What is deep cryogenic treatment?