Lately a good friend of mine has been tutoring me on top end steel.   My blacksmithing experience is mostly limited to mystery metal,  OFS and O1.    He has widened my eyes to the amazing world of technologically advanced steels.   There are stainless steels out there, that hold fine edges with a tenacity that is fairly amazing.  To sharpen them, I really can’t imagine using anything but diamond.

At the same time I am trying to increase my knowledge with older tool methods.   Lately I have been playing around with case hardening.  When you case harden, generally you are looking for a somewhat softer steel center, that will retain it’s fracture resistance.  The outside however you want to be really hard and durable.  This sounds to me like the description of a Japanese Tool Blade.

I decided to try some simple case hardening along with peen hardening on some O1 tool steel.


The process left some fairly bad pitting, on the smaller blade the pitting is  a bunch of tiny pits.


The result of this experiment is some very hard to work steel.    I have not put a proper edge on them, I am still working on it.   I don’t know yet how good an edge I can put on it, but I am pretty sure that the edge I can get on it will hold up.  This steel has become really tough.

The method I used is  to heat the blades to a cherry red heat, and then dip coat the blades in Kasenit.  Then I heat soaked the blades for about an hour to properly bring in the case hardening properties.   I then cleaned them up, coated the bottoms again and treated for about five minutes.   Then I cleaned them up, heated them and quenched them in peanut oil.  After that, I cleaned them up again and then heated them up until I got a straw yellow shade (440F)  on the surface of the steel on the small one.  The larger one, I heat treated to a brownish orange (500F.)

Simple enough metallurgy and not the most careful tempering methods.   While I need to work on my methods and perhaps even grind the Kasenit a bit finer,  this method may end up giving me a fairly nice tool edge,  if I can ever manage the pitting problem.


1 comment to Steel

  • eli griggs

    I’m fairly sure case hardening will not give a good edge tool.

    Japanese tools, for example the woodcut tools, knives, gouges and chisels I use for printmaking on Cherry, Maple and Plywoods, are made with an lamination of wrought iron or mild steel body and a high carbon steel which does the edge work.

    I don’t think I’ve ever seen a Japanese cutting tool made by case hardening.

    Likewise, to the best of my knowledge, old American smiths used laminates, not hardening for edge tool making.

    I most often see case-harden steels used in older firearms, for trigger groups or bolt-release mechanisms on old Mausers for example, parts that need a durable wear surface that are not subjected to the impacts and stresses a tool would need endure.

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