Deep Cyro Processing of 52100 Test Results

Thanks. There will be more and hopefully improved tests into the future.

My process will be changing to high pressure gas quenching in an industrial vacuum furnace. The oil quenching is aviation certified. BTW, I learnt the quenchant the shop used is a fast speed oil quenchant. This is not by design just standard but again, the shop will do any specification.

The new high pressure gas quenching setup in the shop is also certified to various standards and industries including aviation. Trying to get through the sales speak I think there is two immediate benefits to me:

1. Its cleaner on parts
2. I have more variables to fiddle around with. Examples: Amount of pressure (it will do up to 10bar), type of gas quenchant, combining gas quenchants into mixtures etcetc.

I figured I needed an objective and I've settled on producing a hard use survival knife regardless of cost or process complexity or anything else. I want to make myself the very best possible survival knife I can. Im sure there will be allot of failures and learning on the path :thumbup:

I decided I needed to rethink all decisions with my new objective. I've ruled out stainless steel because it comes at too much of a cost to toughness in particular. I will deal with corrosion by other methods. I will continue my 52100 study, but I am also becoming fond of A8 modified the more I learn of its mechanical properties on paper. Please note, I am not saying that such and such is the best knife steel ever, Im just saying I want to explore different materials for my specific needs.
 
Gday KnifeMakers,

Hope everyone had a good holiday over XMAS.

Now that Im back from the break an update. A gent who I respect and has considerable experience indicated to me that his tests showed benefits in cryo processing in cases where previous processing failed to meet the quality marks needed. I am therefore doing further tests to better understand this and he is sending me some further info so I can replicate his results.

I will be reserving the full lab tests until I have made additional test samples with his methods.
 
Cryo should never be used to make up for failed previous treatment !! The whole HT process should be done properly for best results! Steels will have high amounts of retained austenite if overheated .
 
The HT process uses standard temps in a certified shop for aircraft and military work items. It did not fail in that sense I probably worded it poorly.

Basically the gent uses additional processing steps he's sending me info on and he's found with these steps that cyro does not take a knife further with performance. If it gives a benefit thats a sign to him of a quality problem back in the processing.

Im keen to see his info and get more samples made for experiments.
 
nullack said:
Thanks. There will be more and hopefully improved tests into the future.

My process will be changing to high pressure gas quenching in an industrial vacuum furnace. The oil quenching is aviation certified. BTW, I learnt the quenchant the shop used is a fast speed oil quenchant. This is not by design just standard but again, the shop will do any specification.

The new high pressure gas quenching setup in the shop is also certified to various standards and industries including aviation. Trying to get through the sales speak I think there is two immediate benefits to me:

1. Its cleaner on parts
2. I have more variables to fiddle around with. Examples: Amount of pressure (it will do up to 10bar), type of gas quenchant, combining gas quenchants into mixtures etcetc.

I figured I needed an objective and I've settled on producing a hard use survival knife regardless of cost or process complexity or anything else. I want to make myself the very best possible survival knife I can. Im sure there will be allot of failures and learning on the path :thumbup:

I decided I needed to rethink all decisions with my new objective. I've ruled out stainless steel because it comes at too much of a cost to toughness in particular. I will deal with corrosion by other methods. I will continue my 52100 study, but I am also becoming fond of A8 modified the more I learn of its mechanical properties on paper. Please note, I am not saying that such and such is the best knife steel ever, Im just saying I want to explore different materials for my specific needs.
Click to expand...


Any update on this thread?
 
Ed Fowler helped me understand the benefits I was getting was due to lack of quality in processes before the deep cryo processing. I was not converting all the austenite to martensite.

Once I have achieved perfection in my other aspects of heat treating then I will go and explore the claims of better wear resistance from deep cryo processing of tool steels. Until then Im not satisfied the tests are rigorous enough to have meraningful results.
 
nullack said:
Ed Fowler helped me understand the benefits I was getting was due to lack of quality in processes before the deep cryo processing. I was not converting all the austenite to martensite.

Once I have achieved perfection in my other aspects of heat treating then I will go and explore the claims of better wear resistance from deep cryo processing of tool steels. Until then Im not satisfied the tests are rigorous enough to have meraningful results.
Click to expand...

Would it be possible then to have Mr Fowler offer up one of his 52100 blades to be tested against your factory HT'd deep cryo'ed blades? If not perhaps you could send yours to him? I'm really not trying to start a fight here I promise. Everything I've read agrees with what Mr Fowler told you. But, if his methods are indeed superior I'm sure we could all benefit from them, and testing against yours in an objective manner would sure be interesting.....
Matt
 
nullack said:
I was not converting all the austenite to martensite.

Once I have achieved perfection in my other aspects of heat treating then I will go and explore the claims of better wear resistance from deep cryo processing of tool steels. Until then Im not satisfied the tests are rigorous enough to have meraningful results.
Click to expand...

Interesting... I thought you already had all of this accomplished when you offered your previous threads. Would it help you to have a piece of 52100 treated to it's industry standards sent to you for testing? I could see if I could get some metallographic work done on it, too, then send it your way for the next stage!
 
Gday guys.

I should explain what I mean better I think :) All of my old heat treating was done to industry standards. Its just some knifemakers that do non standard things like triple normalising / triple quenching / triple tempering in different combinations to try and get 110% out of the material. To them, industry standard is a lack of quality.

What I know for sure is that cryo does have a positive impact on wear resistance - for example the case studies with tooling dies where the life and costs of the dies are very well understood by a manufacturer and being able to increase it has saved them downtime and money. Thats with industry standard HT profiles.

But, where Im not sure folks is if the same can more easily be achieved by a rigorous heat treatment profile without having to pay someone else with specialised equipment for deep cryo treatment.

I have been working on trying to get my standard heat treat process to 110% so that I can then fairly assess if deep cryo does anything ontop of it. My current experiments involve:

Triple salt batch normalising to reduce grain size and increase toughness
Single salt bath quenching
Triple salt bath tempering

When my tests have shown me I have an optimised HT profile then I will re-explore deep cryo to see if there is anything extra to achieve. I am no longer using 52100 as with the intended use for my specific knives there is better materials than can be used. Please note Im not saying 52100 isnt good for some applications its just for my specific use I have been trialling other materials which have performed better.

Ed has spent many years on his specific 52100 material and HT profile and it would be very interesting to augment that with deep cryo temper processing (being particular about deep cryo -300F not just a home freezer) and then test to see if the grain size, toughness, strength and abrasive wear resistance are in anyway different. These things can be measured objectively and the results would be clear.

Folks Im in Australia. Since most of you are in the USA you have the benefit of more shops doing deep cryo and having easier access to these things.
 
I have found that when cryo makes a big difference, you have not matched the development of your blades to their maximum potential before the cryo treatment. I have only used cryo on 52100, 5160 and what could have been L6.

My method was simple - liquid nitrogen felled Dewar, submerge the blade slowly, let it sit for anywhere from a couple of hours to a week and then warm up slowly in vermiculite or simply set it on a block of wood to warm up. I did not notice any significant difference in the blades other than they felt different when sharpening. Cut was not significantly different when I tempered to the degree where the blades quit chipping with the edge flex and then tested for cut.

Destructive tests indicated the blades were not as tough as non-cryo blades. The repeated 90 degree flexes were done before we started using a torque wrench to measure the force applied. I only used various lengths of pipe on the tangs and evaluation of required force was inaccurate.

I appreciate your sharing what you are learning and will answer any questions you have.

One thought, salts may be influencing your results
 
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