On the interweb....

[Brice Rogers]

I just did a google search to find out the hardness of Kasenit case hardening compound. I found that when applied to 1018 (a very common low carbon steel) that it results in a Rockwell hardness of 60. A little lower than I expected. So when I read about a 75 Rockwell hardness, I guess that there truly is some "secret soup".

[Bill Boehme]

I don't know enough to question any claims, but it seems like the hardness numbers of 1880 Vickers and Rockwell C 75 must be an extrapolation because the information that I could find led me to think that the actual limit on either of these scales doesn't go that high.

[John Keeton]

I have a friend that manages a heat treat facility and we discussed how this might be accomplished. He described various various surface hardening gas treatments that might be used, but apparently their customers simply specify a need for hardness exceeding Rc 65 and so their plant had no way to test beyond that. Nonetheless, he felt it possible to achieve an Rc 75 with the right application. There are also 2-3 branded gas case hardening methods used in the heat industry. He mentioned the names, but I don’t recall them.

Here is a link I found to a place that has a table showing their method will produce as high as Rc 72 on M2. https://www.metlabheattreat.com/nitriding.html

From the conversation I had some of the methods used are at temperatures exceeding the 925* mentioned in the above link. Also, the length of time in the furnace determines the depth of the compound surface - sometimes as much as 36 hours. Heat treat facilities typically charge a per hour rate that could be as much as $125. The pieces cannot touch each other and the maximum load capacity may be limited.

[john taliaferro]

On the rode again , so where does the 6040 come in ?

[Kyle Iwamoto]

Anyone actually have one of these or the Sorby TiN coated gouges? This is very interesting. I would be interested in your $0.02.