Thanks Scott. Here's another article from the same site that I thought was interesting for a couple of reasons.
http://www.industrialheating.com/ar...ogenic-treatment-on-properties-of-tool-steels
This second article as an almost "oh...by the way" states: " Tempering is a very important process in forming useful tool-steel properties because most have secondary-hardening capabilities. This is why all studies that deal with CT should also consider optimizing the tempering process." Which is what you have just suggested.(Less the "forget about Cryo" direction you are suggesting)
Okay, the first article addressed some of the questions that have been niggling at me. And exactly the direction that I have questioned. BUT....I'm not willing to throw out the baby with the bath water here (yet). So lets make a few observations on article 1.(which I also enjoyed) These are not necessarily good or bad or how I feel about what I read, just observations that could be pertinent to how I evaluate an article like that. I indulge myself in a combination of skepticism/sarcasm when re-reading something like this. Not as a means of being intentionally disrespectful, It's how I keep from letting myself get sucked into a frame of thought without challenging the assertions. (We all have some method of doing this or we'd buy everything every salesman ever tried to sell us.)
Author(s)/credentials/sources: One individual authored this. He is the president of a company that does Cryo treatments. Is he a scientist? Or a marketing genius that knows how to utilize his metallurgists to write cool articles? He listed a single source as support. Nothing too alarming here as this is more of an general article than a scientific brief. But the potential for bias is very high.
Ask why the article was written. Two things jump out to me there. First is, this article is damage control by a president of a cryo service company against some of the speculative claims made by industry peers/competetitors. Second is, there is very specific weight given to the importance of the one area the home guys cannot control...ramp time. Subtle message there is "don't waste your time" case for proof is wire treatment. Diagram makes special note of fact that many companies are now treating down to -450 degrees. more subtle message..."Not only can you not control the ever so important ramp time you also can't get it cold enough". Dispatching wild claims lends credence to the author's sense of only advancing truth, which would definitely make a person want to use that company to do their work.
Which statements seem top heavy or exaggerated?:
"Many researchers try to circumvent the timing of the process by immersing materials in liquid nitrogen or liquid helium. At best, there is no change in the performance of the material; at worst, there is catastrophic failure. Unfortunately, the results of these experiments are usually cited as proof that DCT does not work." If this statement were true darn near every blade that A knifemaker cryo'd on his own would fail. The thinness of the material we use coupled with the hardness we are attaining should almost always prove out on the "catastrophic failure" end of things. Yet this isn't so. Enough makers have gone through their own anecdotal testing observing favorable results to give credence to home treatments. If every time I eat bell peppers they disagree with me and my solution of not eating them makes my upset stomach go away. I don't need to find a more scientific reason why I shouldn't eat them. In a similar fashion, No knifemaker is going to routinely do home cryogenic treatments if he has a high degree of failure with no observable improvements "at best". Hopefully the cost, hassle, and lack of any discernible improvements would weed out the temptation to do this just to tell a customer, "Oh yes! It's been treated cryogenically!...."
In fact, rather than saying DCT doesn't work, most knifemakers say it does. This would lead me to question the importance of ramp time. ( I instinctively think that it matters, but, which of us are giving our knives 6-40 hours soak time in the furnace? Maybe heat and cold are apples and oranges when it comes to what matters) Since something is changing that is observable on the home shop front in direct opposition to the "
At best, there is no change in the performance of the material" portion of his statement, I have to wonder if the ramp time issue is being overstated. It is interesting that in the second article, written by four authors, supported by multiple citation of other experts, no mention of ramp time is mentioned in their testing.( I question these guys as to how scientific they were also, though)
Here's another claim that absolutely has my BS meter clanging like a fire alarm:
"Another item holding DCT back is that it is rarely taught in colleges and universities. It is not unusual for metallurgists to state that they have never heard of the process. And again, many are sure that it is just cold treating using colder temperatures and then try to explain it will do nothing." So let me get this straight....This "hidden" technique that I first heard about in trade school 38 years ago is still not being addressed at the university level. And, the droves of metallurgical engineers coming from these myopic universities, who generally are very fact/science driven, have collectively been able to turn a blind eye for the better part of their careers to one of the important exciting areas of advancement in their field. Thank goodness for knife makers as apparently they are carrying the torch of metallurgical discovery forward for the next generation.(actually, sarcasm aside, I think this is true in the area of forging...especially the Damascus stuff.) Then when I read a statement like the above one I ask, how many metallurgists did you survey? How many universities did you contact about course content? How many tried to explain to you that DCT will do nothing?
I did like the article. He went after the key point that I have been puzzling over but that only means I need to be cautious to not internally think, "Yep, an expert agreed with my guess. Must all be smoke and mirrors....".
I would like to hear what Kevin C. thought about that article.
Sorry for the philibuster....coffee and keyboards don't mix....:biggrin:
