San-mai Hunter - delamination and weird metal?

[Alveprins]

Ok, so I wanted to make something a little special...

I decided to combine modern #20 steel for the edge, and some - I presumed iron - I'd dug out of the ground on my property which I bought last year. (The oldest part of my house is dated to around 1820)

So.. I found this round iron wedge under my old storehouse, along with some chains and farm equipment for digging in the earth and whatnot... So I decided to use the wedge for the san-mai lamination.

I drew it out into two flat bars, cleaned them up, and added the modern steel.

 

While working on the forge weld, I noticed the mystery-metal was extremely soft, and it felt as if it would not "take" very well... And by "take", I mean stick to the steel. I found it to be somewhat difficult to get it laminated. The "iron" would simply be squeezed around the carbon steel in the middle - as a result of their quite different levels of hardness obviously.

 

Anyhow, I could see the blade starting to de-laminate even at normalization, so I dropped the differential hardening and just went for a straight quench instead. I got two normalization cycles in before quencing. I let the blade air-cool all the way down to +23C before re-heating.

 

Anyhow, here are some pics:

 

BEFORE QUENCH:

 

AFTER QUENCH:

 

Notice the extreme difference in color between the edge and the jacket?

 

AFTER #120 SANDPAPER:

 

I have no previous experience with iron - so I am asking... Is this how iron looks in contrast to steel in a lamination like this?

I thought it looked so special, I could not bring myself to discart the blade. I feel the historical significance of the iron or whatever it is - is too valuable to me to simply discart this otherwise fine blade.

The mystery-metal does not even seem to have taken the quench... Hardness is like - less than 40HRC. But the edge on the other hand is as expected 63HRC - which is as high as this particular steel goes. It current rests in my oven at 200C...

 

Oh, and that delamination near the handle area? - I cheated and welded that bastard shut with my arch welder!

 

I'll hapilly take any input and thoughts on that "iron" or whatnot though... I havent seen coloration like that before...

 

Sincerely, Alveprins.

[Alan Longmire]

That is not unusual for old wrought iron. The color and softness and spreading over the steel during forging is normal and to be expected. As for not wanting to stick, wrought iron welds at a much higher temperature than high carbon steel. Of course you don't want to burn the steel, but take it as hot as it can go next time and I suspect your welds will be happier. In general when forging wrought, work it from welding heat down into bright yellow, don't try to work it colder than that or it tends to fray or crumble, especially if it has an amount of phosphorus in it.

 

I do like to play with it, and I suspect you will as well. It's a different material than modern steel and no two pieces work just the same.

[Alveprins]

That is not unusual for old wrought iron. The color and softness and spreading over the steel during forging is normal and to be expected. As for not wanting to stick, wrought iron welds at a much higher temperature than high carbon steel. Of course you don't want to burn the steel, but take it as hot as it can go next time and I suspect your welds will be happier. In general when forging wrought, work it from welding heat down into bright yellow, don't try to work it colder than that or it tends to fray or crumble, especially if it has an amount of phosphorus in it.

 

I do like to play with it, and I suspect you will as well. It's a different material than modern steel and no two pieces work just the same.

Excellent Mr. Longmire!

 

Thank you very much for that answer.

 

I've wanted to work with wrought iron for a while now, but havent known where to get it... I suppose digging around in the dirt around my house might be a good source.

 

Well, at least my weld was around 90% successfull though.... haha

 

I think this knife will become a special little piece none the less.

[Lars Holen]

See what turns up after an etch!