Jump to content

heat treating bloomery steel....


Recommended Posts

I have been slipping a few bloomery blades in with my normal workload just to keep me feeling free.....

 

I am making san mai construction blades, seems safer that way , the iron at the sides and spine defiantly makes them a forgiving blade.

I am having good luck brine quenching them from 780C heat treating them at a low temper (190C).

I am sticking to a single normalisation as I have had problems with reduced hardness in the past, I will probably play around with this though.

 

I am still oil quenching bigger seax blades made from this material as I am a little unsure of a brine quench on a large chopping blade. The couple of bloom axes I have made seem to perform fine but need a slightly more obtuse edge angle than a modern steel in order to keep a good edge.

 

Over the last few years I have had a few knives doing their job in the kitchen and I have enjoyed getting to know them , the pil quenched blades are soft (by modern comparison ) but take a good edge and sharpen wonderfully off of a steel.

 

The brine quenched blades seem to work very well, take a good edge and keep it a lot better , my go to workshop knife is a brine quenched bloomery seax ....

 

All in all the material in nice to use but defiantly not a modern super steel.

I am interested in how any of you are heat treating your own bloomery steel.

All the best Owen

Link to post
Share on other sites

Talking only about long blades 2 foot long cutting edge or so...

I have had no luck using modern fast oils. I only get 1-3 mm of hardening using those.

So I go into warm water for 3-4 seconds then into oil. This produces enough hardening to create a nice hamon and it is more forgiving than leaving the blade in the water all the time. A little longer than 3 seconds in the water and the likelihood of cracks increases dramatically which makes me wonder about microfractures even in the ones that survive.

I have not tried brine but you have piqued my curiosity.

Link to post
Share on other sites

The first bloomery blades that i made were water quenched as ann interrupted quench into water and oil, and were clayed and of a japanese style.

it certainly works for that type of blade.

I am making wider and thinner blades now and brine seems to work well.

I have tried all sorts to get fast oil working but basically have the same results as Jesus, ie very shallow hardening. tried multiple oil temps and long low blade soaks . lucky to get a 2mm depth of hardening.

Link to post
Share on other sites

For the past year, I have been using warm brine, and then oil interrupted, or just the brine.

 

I do make quite a few iron age blades. Many without enough carbon to fully harden. I just run these through the brine quench for good measure, and hope the banding doesn't bend them up too much.

I've only had a couple crack.

 

Getting ready to quench a long sword made totally from High Carbon, hearth-refined bloom steel. A bit worried about how to quench that one. Likely just oil, or maybe even edge quenching??




Link to post
Share on other sites

I've only made a few small blades from "orishigane", hearth steel, whatever you call it.

I'm not sure how it compares to more strictly kosher bloom steel, but I have had good results with the strictly trad heat treat of heating to cherry red, quench in warm water, wipe with animal fat, heat till fat just begins to smoke. Basically a 1940's EN9 sort of heat treat, but perhaps less of a crap shoot than the material itself.

Link to post
Share on other sites

When you refer to brine, do you mean a saturated solution of water and sodium chloride or more like a seawater high concentration or some other salt apart from sodium chloride? Can someone explain to me what the mechanisms/benefits of brine over water are? Is it heat capacity/thermal conductivity?

 

While i am at it, what edge thickness would you gus recommend for a tanto style knive of .6 to 0.8/ carbon content. I was aiming for 1mm but am not sure if that might be too thin even with clay hardening.

Edited by Philippe Brasseur
Link to post
Share on other sites

I believe the going only with one or two normalizing cycles would be the most difficult thing to get used to at least for me. I believe the benefit of a brine quench is that the salt helps keep the vapor jacket from forming so easily and provides a more even quench than just water alone. How much hotter do you all go when quenching bloomery steel, versus a monosteel blade of the same carbon percentage?

Link to post
Share on other sites
  • 1 month later...

Going from working almost exclusively with L6, to working with bloom steel and blister steel has been one of the most rewarding changes that I have made. Working with getting the heat treat down and embracing the difference in hardness and toughness from what I have been familiar with achieving has been humbling. So far I have been quenching into warm water, 140F or so, little soak time at temperature. I am in the process of rebuilding my heat treat setup so I don't have an actual temp, but should be resolved in the next few days. I have had very good results with carburizing prior to heat treat, practiced on a seax with success, about to give a sword a go next week. I tried a variety of quench samples from the stock and couldn't get it harden much, even tried a super quench solution. Hoping gain a touch of hardness.

Link to post
Share on other sites

I am still keen on brine, however I have had a few tinks on wider blades. So my experimenting continues.

Edited by owen bush
Link to post
Share on other sites

I ran into this problem a few years back and was advised by fellow forum participants ( Niko and Greg ) to go to a higher temperature before quenching..I had normalized the steel ( iron?) and still had an extremely fine grain going into the quench.

 

Jan

Edited by Jan Ysselstein
Link to post
Share on other sites

With either oroshigane, or my experiments with ore, I found oil, and brine just weren't aggressive enough.

So I tend to use boiled water for clayed work, when I want to follow the hamon as designed, or without clay I use cold water, as it produces interesting auto hamon effects.

I don't have a set amount of time in the quench tank, I feel the reaction of the blade, and act accordingly.

Then back over the forge(without the blower on) slowly bring it up to straw, quench, repeat, clean with a stone, how she feels on the stone dictates if I need to take out anymore hardness.

I have never had a crack, but have had delamination twice.

Never tried through hardening bloomery steel.

Link to post
Share on other sites

My Problems with Brine seem to be thin blades 2 inches wide or over and I think interrupting the quench and immediate high thermal capacity temper into hot oil would be my best Bet.

I find brine much deeper hardening than plain water..

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...