What are the white lines on this blade?

[Lee Sauder]

I wasn't sure where to put this, so I just put it here at home.

I made a little all steel knife, and I see something I don't recognize. This is all steel, it's the leftover from the bit of this axe . It's several miscellaneous bits of hearth steel from bloom iron, mostly I think from magnetite. Also a little bit of steel I made by cementation in the forge. When I etched it, there were these whitish lines. They're not really bright, but white, almost a little dusty looking. I don't know if the photo shows it very well, but i wonder if you guys have any hypotheses? Oh yeah, etched in Ferric.

Edited April 1, 2013 by Lee Sauder

[Jesus Hernandez]

Lee, those are areas of decarburization on the surface of welds.

[Darrell @ warehamforge.ca]

Lee

(Where ARE you? I thought you were off to New Zeland??)

 

Like you, I have been trying to avoid turning directly to knives with my blooms. Not that I would have been influenced by your work or anything (!!).

 

I have made only a couple of blades out of the bloom material, those primarily smaller and simpler pieces more for the historical accuracy than anything else. However, I did notice the same effect on one that I had test etched in - Ferric Chloride. I also had a very subtle light grey shading in thinner lines. That piece was from a very clean and smaller pieces of one bloom, which I had to only draw and weld a couple of times to get solid compact metal.

I know that is a horrible image - and you can see that primarily there are the darker lines in the solid surface - which I took to be a carbon movement to the weld boarders (??)

The full image is reduced to black and white - but you can see the same (??) in a whitish set of lines over the surface.

 

As if I *understood* this - but certainly have seen the effect you describe

Darrell

[Lee Sauder]

Lee, those are areas of decarburization on the surface of welds.

It doesn't seem like that. It's almost chalky looking. I could almost buy borax coming out, but I repolished and etched it 3 times.You can sorta see it darkened a little near the edge where there was lots of oil from sharpening, though the whole blade got oiled.

 

As i sit here and look at it, it's hazy character almost reminds me of a hamon.

 

I'm smelting tomorrow if you just wanna come look at it and hang out.

[Lee Sauder]

Somehow I couldn't get my camera to take a real close-up earlier, but it changed it's mind. This is from the other side of the blade, where the effect is spottier. You still think decarb?

 

[John Page]

Sorry I don't have any insight, Lee, but that is a fascinating phenomena. It looks almost like stone with veins running through it. Very interesting!

 

John

[ZebDeming]

I wonder if it may be something similar to a hamon, following slag inclusions that may act as an insulator during the quench, like a clay coating would.

[joe pierre]

funny... i got the same "candy cane" effect on a tanto i made in michael bell's class some years ago. we weren't really sure what it was, but like yours, it follows the weld lines at what seems like regular intervals.

 

look up on the shinogi:

 

 

 

[Jesus Hernandez]

I can't make it, Lee. My in-laws are here.

I am positive those are areas of decarb. Remember that ferric etches carbon-high areas dark. Those milky lines more or less follow the areas were the your weld was set. During the welding heat if the fire is too hot or if its kept in the fire for too long the two surfaces to be welded will experience some decarb. Heck, it even happens when the fire is not hot in a gas forge and might have to do more with time at that temp. If you look closely you will notice a dark line running down the middle which is the actual weld with some slag inclusions.

[Lee Sauder]

I can't make it, Lee. My in-laws are here.

I am positive those are areas of decarb. Remember that ferric etches carbon-high areas dark. Those milky lines more or less follow the areas were the your weld was set. During the welding heat if the fire is too hot or if its kept in the fire for too long the two surfaces to be welded will experience some decarb. Heck, it even happens when the fire is not hot in a gas forge and might have to do more with time at that temp. If you look closely you will notice a dark line running down the middle which is the actual weld with some slag inclusions.

 

Change of plans anyway- smelting tomorrow (slap out of firewood and it's still cold!)

 

OK, I'll accept decarb. I realize this probably follows a line where my weld split a little on the twist, so I fluxed it and had to work at it a bit to get it closed back up., which would also explain why ir comes and goes, in places where it didn't split, or where it welded back up on the first heat. I guess I haven't seen this before because all the other knives had phosphoric components blocking carbon migration, and hiding it in it's own bright lines when it did decarb.

 

Which brings another question- does borax have a tendency to decarburize more than other fluxes? Kinda seems that way to me, but I don't understand the chemistry of borax.

[Mark Green]

Lee, I have had those lines in most everything I have made with home-made steel/iron. Straight from bloom, or hearth, or folded up from bloom/hearth.
Seems to just be the nature of the beast. With carbon content being all over, and moving around, and added heat.

 

Here is one I made direct from the hearth smelt. No extra processing. It has lighter, and darker streaks running all through it.

 

 

Both made the same way.

 

 

Can't get my pics to post????

 

 

 

 

Edited April 2, 2013 by Mark Green

[Lee Sauder]

Skip and I polished up the remnants of this billet, did several etches, hillbilly hardness tests, microscopy, etc. Jesus is right- It is indeed decarburization.

 

Notice that this is not along folds, per se, as Darrell noted, or intrinsic in the piece, as in Mark's example. It happened on the last heats, on the corners of the twists.

 

What's is especially interesting to me is that I've made a couple of dozen blades like this, and haven't seen this before. I don't know if I've just been lucky, or that the previous blades in this series had phosphoric iron layers, which blocked the carbon migration and prevented the decarb. I certainly feel like I've lost less carbon in PW materials that had phosphoric layers than in the few I've made that didn't include phosphoric layers.

 

I think it's very lovely though, I wonder if I can do it on purpose?

[strix]

looks like a marble knife, kinda cool