Try having a few samples Rockwell tested for hardness. You'll probably be surprised.
I think this is one of those debates where different people are satisfied with different levels of performance. Kevin is trying to tell us how to get the best possible performance out of a given steel--namely, follow the instructions of the scientists who have spent years and millions of dollars in perfecting the process for handling their steel.
The "it seems to hold an edge pretty good" crowd is sorta right, too. I've made some straight razors in the 52-54 Rockwell C range, and they shaved pretty nicely.
However, let's not pretend that we're getting the maximum performance out of a given steel if we're not using the proper austenizing temperatures, suitable quenching oils, and appropriate tempering temperatures.
It's kind of a shame to pay for a Corvette and be satisfied when it performs like a Chevette, but hey, some people just need to get to the grocery store.
Josh
Josh I agree 100% with your statement, however I cringe at the use of the "sci.." word in the second paragraph. I have no problem with it but it opens your excellent argument up to that same tired, old knee-jerk reaction, as if you have said that priests had spent years developing something.
So I would like to verify things by saying that I am
not a scientist, I am just a bladesmith, however I have looked into this subject for years, using Rockwell testing and micro-imaging, I even have some of those images, which I have shared in the past. With a steel like 1095, with a window of success at 1000F of around one half of a second, quench speed is extremely critical and the consequences of ignoring that can be summed up in two words- fine pearlite.
Although the file as a definitive test is easily blown completely out of the water, it is still worth reiterating that a file can not detect fine pearlite intermingled with martensite, it can only indicate it when there is a majority of pearlite. On the flip side, when quench speed is too fast, such as using the fast oil with O-1, you
do get micro cracking (something else I have plenty of first hand images of), which will not be at all evident and the knife may take abuse for years only to catastrophically fail when you least expect it.
Qualifying a heat treatment on an immediate pass fail basis doesn't work so well. It is like the habitual deep fried Twinkie eater saying that healthy foods are a gimmick since they have not dropped dead yet. On the short term a full medical examination would indeed show more immediate consequences of spurning real food, but if one really looked at the performance of the Twinkie eater compared to a health conscious individual, the signs would be there.
The truth be told from what I have seen described as a fine performing knife in my career, I would say that one could quench 1095 in warm mud and still have it come out as acceptable for many users (i.e. our Twinkie eaters only have to get their fat asses from the couch to the kitchen to be considered fit, a marathon would be another story). We simply do not use our knives to the level all the marketing has us believing we do, and let's face it all a knife has to do to work is cut objects softer than itself, something that even paper can do if we grab it wrong.
I have yet to meet anybody who intentionally sets out to do something half-assed even on a one time or hobbyist basis. It is human nature to say that if this is worth the time doing it is worth doing the best you can. In the making of the knife the three most important things for performance are- 1. The heat treatment, 2. The heat treatment and 3. The heat treatment. So just as I doubt anybody sets out to make the worst looking knife they can, I also assume they want advice on how to achieve the very best heat treatment they can. I assume that I am doing the greatest favor by suggesting proven products developed by and for industries that are a whole lot more serious and critical on results than knifemakers. Oil companies or scientists are not responsible for heat treating products, industries that have to have the heat treatment dead on, every time, developed these oils! We have the luxury of pooh poohing them because we simply do not have to meet the same high standards.
Putting any effects on the steel aside, we can now talk about consistency and long term value. Heat treating oils are designed to take 1500F parts plunged into them day in and day out with still providing the same results in the 10th batch as they did the first. Let’s say something off the super market shelf does indeed nail it dead on the first time, where will it be ten blades later? Oxidation, natural decomposition (something more familiar to organic oils than mineral based products*) thermal breakdown, sludging etc... When factoring in predictability over time the fancy oils start to look a little cheaper, and then when you bring performance back into the picture, they start to look like the most value for your buck.
* edited to add that although this could leave an opening for the “just plain mineral oil is cheaper for the same thing” crowd, it should be pointed out that quench oil in not just mineral oil. 0.39% is a very small amount of anything yet that is all it takes to make the huge difference between the behavior 1045 and 1084. It is called chemistry. (why only have half of the folks mad at me when I can have them all
)
Fitzo hand me another Dixie cup, it looks like I just used another whole pack
