Does Cryogenic Treatment Work on Stainless Steel? It Depends on the Grade
Most plants asking this question did not choose stainless. It was chosen for them — by a wash-down regime, a food-safety standard, or a corrosion problem that ruled everything else out. The question is not whether stainless is the right material. It is whether anything can be done about the material you are stuck with.
Cryogenic treatment can, for some grades. The difference between them is large enough that a blanket answer is useless, so here is what the published research shows, grade by grade — including the grade where it did nothing at all.
Why You Are Running Stainless in the First Place
In a meat plant, a dairy, a bakery or a pharmaceutical line, stainless is a requirement before it is an engineering decision. You cannot swap a blade to D2 because it holds an edge longer, and you cannot plate your way out of daily caustic wash-down. So you run a material chosen for corrosion resistance and cleanability, and you accept what comes with it: it dulls sooner than the tool steel you would rather use, and it galls — welds to itself under pressure — where parts rub.
That is the trade. The useful question is which part of it can be improved without changing the material, and the answer turns entirely on what kind of stainless you have.
Why the Grade Decides Everything
Deep cryogenic treatment takes hardened steel down near the boiling point of liquid nitrogen, holds it there, and brings it back on a controlled ramp. Two things happen in the metal, and only the first is widely understood.
Retained austenite — soft structure left over from quenching that never finished transforming — converts to martensite. And fine carbides precipitate through the structure, which is what most of the measured wear improvement is attributed to.
That first mechanism is why grade matters so much. A steel can only benefit from retained austenite conversion if it has retained austenite to convert. Martensitic stainless does, because hardening it is what leaves the austenite behind. Austenitic stainless is austenitic by design — there is nothing there to transform. Cryogenic treatment explains the process from the beginning if you want the longer version.
440C — Where the Evidence Is Strongest
A 2020 PhD thesis at the University of Sheffield put 440C through a conventional heat treatment, gave half the samples a deep cryogenic treatment, and measured both with Vickers hardness testing and an abrasive wear rig built to the ASTM G65 standard.
Hardness rose by at least 16.9%. The author attributes it directly to retained austenite transforming into martensite — the mechanism above, measured.
That is a laboratory result on test coupons, not a promise about your blades. But 440C is the grade where mechanism, measurement and application line up. It is the high-carbon martensitic stainless used for blades, knives, grinder plates and bearings precisely because it can be hardened — and hardening it is exactly what leaves retained austenite behind.
440C is the bulk of the stainless we treat, and 420 — the softer, tougher martensitic grade used in food-processing blades, moulds and surgical instruments — goes through the same process.
420 — The Other Blade Grade
A 2017 study in the Beilstein Journal of Nanotechnology treated AISI 420 at −196 °C for two hours and examined the surface at the nanoscale. Alongside its own findings it reports the group's earlier macroscale work: a 35% improvement in wear under lubricated conditions, and 90% under dry sliding, with a 2–5% reduction in friction.
The gap between those two numbers is worth sitting with. Dry sliding is the harsher test, and it is where the treatment helped most — which is what the mechanism predicts, because that is where surface wear dominates and there is no lubricant film carrying part of the load.
304 and 316 — One Surprise, One Null Result
This is where a blanket claim about “stainless” falls apart, and where the honest answer is more interesting than the marketing one. The same Sheffield study tested two austenitic grades under identical conditions.
AISI 304L improved, substantially. Hardness barely moved — up 1.8% — but wear volume fell by 31.8%. The mechanism is not retained austenite conversion, because there is none to convert. The author attributes it to nano-martensite particles nucleating at the intersections of dislocations, and calls it the novel finding of the work: the treatment is viable for 304L under abrasive wear even though the classic mechanism does not apply.
AISI 316L showed nothing. No measurable difference in hardness. No measurable difference in wear volume. Same treatment, same rig, same laboratory, same thesis.
Two austenitic stainless steels, a molybdenum addition apart, and one responded while the other did not. Anyone who tells you cryogenic treatment “works on stainless steel” has not read the comparison.
The Same Alloy, Printed, Is Not the Same Material
The 316L null result above was measured on conventional wrought bar. That matters more than it sounds, because 316L is now one of the most commonly 3D-printed metals there is — and printed 316L is not the same material as rolled 316L. It comes out of the machine with residual porosity, a melt-pool grain structure and locked-in stresses that wrought bar simply does not have.
Two separate studies have run cryogenic treatment on additively manufactured 316L. Both found that it responds.
The first, published in Tribology in Industry in 2019, treated 316L made by direct metal laser sintering at −196 °C for 24 hours. The porosity in the printed material was greatly reduced, the coefficient of friction fell considerably, and hardness rose — which the authors attribute to a strain-induced phase change. Their wear-track images show abrasive particles bedding into the pores of the untreated samples, which is a failure mode wrought bar does not have to begin with.
The second, published in High Temperature Corrosion of Materials in 2024, treated selective-laser-melted 316L at −196 °C for 120 hours and measured it more closely. Average grain size fell from 1.01 µm to 0.78 µm. Microhardness rose from 193.16 HV to 222.6 HV, an increase of 15.24%. Surface roughness dropped 3.23%. And the corrosion rate fell from 0.004695 to 0.003965 mm/year.
The two papers do not agree on why. The 2019 authors credit a strain-induced phase change; the 2024 authors ran X-ray diffraction, found no change in crystal structure at all — both samples plain FCC austenite — and credit grain refinement instead. So the effect has now turned up twice in printed 316L, and the explanation for it is still open. We would rather tell you that than pick whichever mechanism sounds more convincing.
The practical point is the one this whole page keeps arriving at: the grade on the certificate is not the whole description of the material. How it was made is part of the description too. If you are running printed stainless parts, the wrought 316L null result does not describe them.
One Study Is One Set of Parameters
Before those numbers get treated as settled, it is worth saying what they actually are: results from specific cycles, run once, in two laboratories. Cryogenic treatment is not one process. It is a family of them, and the settings move the outcome.
The Sheffield work cooled its samples at about 2 K per minute to 93 K — roughly −292 °F — held them there for 14 hours, and warmed them back at the same rate. The Beilstein study used a different cycle entirely: −196 °C (about 77 K) for two hours. Same broad technique, a hundred degrees Fahrenheit and twelve hours apart.
That matters because the Sheffield thesis names soaking temperature as the dominant parameter of the treatment, and closes by recommending exactly the experiment nobody has run: take one alloy and put it through a range of different cryogenic cycles. Until someone does that, a null result tells you that one cycle did not move that property in that test — not that the alloy cannot respond.
For comparison, our production cycles hold between −308 °F and −312 °F — about 82 to 84 K, some 10 K colder than the cycle that produced the 316L null result above. We are not claiming that closes the gap; we have not run that comparison in a laboratory and we will not pretend otherwise. We are saying the published figures describe the cycles the authors chose, and there is a great deal of room either side of them.
This is why we would rather measure your parts than argue from a paper. Where a customer is willing to count parts between changes, we do — and when a first set of parameters produces a modest gain, changing them is often what produces a larger one. Those are the numbers worth having, and they are the ones we are accumulating.
Why We Publish Someone Else’s Numbers and Not Our Own
A fair question to ask at this point: if this is our trade, why is every figure on this page from a university?
Because those are the ones you can check. A published paper names its alloy, its cycle, its test method and its sample count, and you can read it without taking our word for anything. That is the honest way to state what is established, so it is what we put in writing.
It is not the limit of what we see. We have been refining our own cycles since 1980, and on customer parts we regularly see results beyond what the published cycles produced — sometimes considerably beyond, and sometimes only after we change the parameters and run it again. The gains are real and they are measured, on the customer’s own line, counting their own parts.
What we usually cannot do is show them to you. The customers with the best data tend to be the largest companies, and a request to publish a tooling result travels through a legal department whose job is to say no to things that carry no upside for them. Confidentiality agreements sweep in process data by default. None of that means the results are weak — it means the people who own them have nothing to gain by letting us print them.
So this page holds the line at what is verifiable, and we would rather say plainly that the rest exists than dress up a number we cannot source. Two things follow from that, and both are practical:
- We ask for permission before a trial starts now, not after the numbers are good. Asking afterwards sounds self-interested and the answer hardens.
- The result that matters to you is yours. Run treated and untreated parts side by side on your own line and count. That number owes nothing to a paper or to us.
What That Means on a Plant Floor
| Grade | What the research measured | Typical parts |
|---|---|---|
| 440C martensitic | Hardness +16.9% | Blades, knives, grinder plates, bearings |
| 420 martensitic | Wear −35% lubricated, −90% dry sliding | Blades, moulds, instruments |
| 304L austenitic | Wear volume −31.8%, hardness +1.8% | Tanks, guides, wear plates, conveyors |
| 316L austenitic, wrought | No measurable change | Wash-down surfaces, piping, vessels |
| 316L austenitic, 3D-printed | Hardness +15.24%, corrosion rate −15.5%, friction and porosity down | Printed brackets, manifolds, one-off fittings |
Each figure above comes from one published cycle, not from a survey of cycles. See the section above on why that matters.
The pattern is more useful than the individual numbers: the parts worth treating are the ones you replace most often. Blades and grinder plates are consumables bought on a schedule. Tanks and piping are not.
If your line runs 440C or 420 blades, that is where to start — and the number to hold on to is your current change interval, not hardness, which nobody on a plant floor measures. What a real cycle includes covers how to cost that out.
Where It Does Not Help
- Do not buy it for corrosion resistance. The one study that measured corrosion on treated stainless found a real improvement and called it marginal in the same breath: on printed 316L the corrosion rate fell from 0.004695 to 0.003965 mm/year, about 15.5%, which the authors themselves describe as marginal. Elsewhere the literature is inconsistent. If corrosion is your failure mode, treat that as a footnote rather than a solution.
- It will not replace heat treatment. It is an addition to a proper hardening cycle, not a substitute for one. A badly hardened blade comes back a badly hardened blade.
- It will not fix a design or geometry problem. If a blade is failing because the clearance is wrong or the edge geometry is unsuited to the product, a colder blade fails the same way.
- Wrought 316L did not respond to the one published cycle it has been tested under. That is a reason to treat it as unproven rather than promising — not a reason to conclude it can never respond to any cycle. Printed 316L, as above, is a different case.
It also cannot be undone — which is the other half of the same coin. It is a through-treatment rather than a coating, so it survives resharpening instead of disappearing at the first grind.
How We Run It
Our production cycles hold between −308 °F and −312 °F. The processors are vacuum-insulated tightly enough to sit that close to liquid nitrogen's own boiling point of −320.4 °F, and the closer a cycle runs to that point, the better the effect on the alloy. Parts go down on a controlled ramp, soak, and come back slowly. CTP has been doing this in Torrance, California since 1980.
For stainless parts that gall rather than simply wear, the surface is the other half of the problem. WPC Treatment® — micro-dimpling — textures the finished surface so it holds lubricant and carries compressive stress, which reaches failure modes cryogenic treatment alone cannot.
Frequently Asked Questions
Does cryogenic treatment make stainless steel harder?
For martensitic grades, yes. A University of Sheffield study measured a 16.9% hardness increase in 440C, caused by retained austenite transforming to martensite. For austenitic grades the hardness change is small: 1.8% in 304L, and nothing measurable in 316L.
Does it work on 304 stainless?
For wear, yes, though not by the usual mechanism. The same study measured a 31.8% reduction in wear volume in 304L, attributed to nano-martensite forming at dislocation intersections rather than to retained austenite conversion.
Does it work on 316 stainless?
Wrought 316L did not, under the one cycle it has been published against. In the Sheffield study it showed no measurable change in hardness or wear volume — but that was a single set of parameters (93 K, 14-hour soak), and the same thesis names soak temperature as the dominant variable and calls for the multi-parameter study nobody has run. Additively manufactured 316L is a different story: two studies found it does respond, with hardness up 15.24% in the more recent one. We would call wrought 316L unproven rather than ruled out, and printed 316L worth a trial.
Will it affect corrosion resistance?
Do not buy the treatment for corrosion. One 2024 study measured it directly on printed 316L and found the corrosion rate fell from 0.004695 to 0.003965 mm/year — a real reduction of about 15.5%, which the authors themselves call marginal. Elsewhere the literature is inconsistent. Corrosion performance is the one property a food plant cannot afford to gamble with, so we would rather you took that as a footnote than as a reason to treat.
Can you treat finished, sharpened blades?
Yes. It is a through-treatment at low temperature, so there is no scaling, no distortion from heat and no coating to wear through. Parts come back dimensionally as they went in.
How much longer will a treated blade last?
That depends on your product, your line speed and what is actually wearing the blade. The honest way to find out is to run treated and untreated blades side by side on the same machine and count parts between changes. We would rather you measured it than took our word for it.
Sources
- Herrera, P. (2020). Effect of Cryogenic Treatment on the Abrasive Wear Resistance of Engineering Alloys. PhD thesis, University of Sheffield, Department of Mechanical Engineering. Full text. Source of the 440C, 304L and 316L figures.
- Prieto, G., Bakoglidis, K.D., Tuckart, W.R., Broitman, E. (2017). Nanotribological behavior of deep cryogenically treated martensitic stainless steel. Beilstein Journal of Nanotechnology. Full text. Source of the AISI 420 figures.
- Sugavaneswaran, M., Kulkarni, A. (2019). Effect of Cryogenic Treatment on the Wear Behavior of Additive Manufactured 316L Stainless Steel. Tribology in Industry, 41(1), 33–42. DOI 10.24874/ti.2019.41.01.04. Source of the porosity, friction and hardness findings on DMLS 316L.
- Sreejith, N.K., Satheeshkumar, V., Anaz Khan, M., Ram Prabhu, T. (2024). Experimental Investigation on the Influence of Deep Cryogenic Soaking of Additive Manufactured SS 316L on Hardness and Corrosion Resistance. High Temperature Corrosion of Materials, 101, 369–388. DOI 10.1007/s11085-024-10235-0. Source of the grain size, microhardness, surface roughness and corrosion rate figures on SLM 316L.
All four are published and peer-reviewed; the first two are open access in full and the others publish their figures in the abstract, so you can check the numbers rather than take them from us. Laboratory results on test coupons are not a prediction for your parts — they are the reason to run a trial, not a substitute for one.
Send One Blade
If you run 440C or 420 blades, the way to find out what it does on your line is to treat a few and count parts between changes against your current ones.