Last night I quenched my first tanto. It's made out of 80crv2, I coated it in rutland fireplace mortar, going all the way to the edge in thin strips in some places (the pattern kind of shows up in the oxidation) and quenched it in warm canola oil. After I scraped off the clay I ran a file down the spine and it bit in and it skated on the edge so I know that it differentially hardened to at least some extent. I have two questions: first, should I have quenched it in water? I didn't want to at first because I wasn't using a simple carbon steel. Second, I was wondering if there's any way to check if there is a hamon in a blade before the final polish. On pattern welded blades I usually do a few test etches after forging and hardening to get an idea of what the pattern is going to look like and to check fro any problems. Would the same work fro a hamon (as in being able to see it when etched at 80 or 120 grit)? (also I wasn't sure if this should go in the heat treating forum or here because it is a technique mostly used on knives).

 

Edited March 10, 201511 yr by AidenCC

I'm interested to see the response to this as well, I've been wondering about this! 

If i was hardening a steel I did not know too well and trying to get hamon to a specific depth  by oil quenching with clay on the blade I would do the following.

 Take best guess at oil temp and blade temp . Normalise the blade. Harden the blade. As soon as its cooled down and before temper I would run it over the grinder at 36 grit. You can often tell the depth of Hamon looking at the blade obliquely at 36 grit. If its where you want it . Then temper and clean up as usual. 

 The reason I would do this immediately is that I could then re heat treat the blade Try and move the Hamon up or down the blade by changing the blade temp , oil temp and clay thickness/ position, edge thickness.

Remember that if you multiple normalise and then multiple quench you will be reducing the hardenability of the blade each time you do this. This can be beneficial in a deep hardening steel as you can literaly chase the Hamon up the blade by multiple normalisations/quenches.

If you want to etch you will need to be up past 120/200 grit to see the Hamon again , any lower and the grit marks will show more obviously than the Hamon.

You may not see fine detail untill you are up in the 800 to 1000 grit range.

Hope that makes sence.

Was your blade straight backed when you hardened it?

It looks to have a little negative sori, but it's hard to tell without seeing the blade pre quench.

Was your blade straight backed when you hardened it?

It looks to have a little negative sori, but it's hard to tell without seeing the blade pre quench.

​

Not the best picture, but the only one I have pre-quench. The lack of any major curving was part of the reason I was wondering how well the differential hardening had worked. The blade is already tempered and because of a clearance problem the coarsest belt I can fit on my grinder is 80 grit (working on fixing that). If the belt is a little dull and 80 grit would I still be able to see a faint hamon?