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Will Urban

First crucible steel puck going for wootz.

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Hope you get some good results Will!

 

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Any results Will? Am just reading all I can at the moment would love to have a go at Wootz.

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As soon as I get the results I will definitely post them to the forum.

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So I have gotten the results. The bloom iron I've been using is the lower carbon and the crucible is obviously the other

20200306_065409.jpg

20200306_065347.jpg

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Phosphorous is wayyyyyy too high.

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Thanks daniel that was something that jumped out to me immediately as well the bloom iron itself isn't all that high so I need to dial back and figure out where I'm picking up almost a full tenth of a percent of phosphorus. I also noticed the copper and silicon numbers went up from bloom to crucible but I'm not sure how significant that is.

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If I'm assuming correct the phosphorus would make the dendritic pattern more visible but would lead to a lot of problems forging in terms of cracking and crumbling. Which would definitely explain most of my problems. What would a preferable phosphorous cutoff point be?

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Posted (edited)

Hey Will, as Daniel said, your Phosphrous level in the ingot is way too high (maximum is 0.05%), if you want to remove P from the ingot you can add Calcium Carbonate or shell to the melt and that will help to lower the level.  P in an ingot will make the lines more fuzzy and less defined, cold short and to a degree hot short.  The carbides increase in number but the contrast drops.

The main problem though is that you have too much Sulphur (over 0.02%) which will make your ingot crack when forging too hot or too fast. 

 

The other issue is your Silicon level is a bit high (should be below 0.1%) and it may be adding to your troubles but not as much as your Sulphur. Adding some Manganese will reduce the sulphur levels but don't add too much or you will have the pattern darken.  Calcium Oxide will react with Silicon to form the flux Calcium Silicate which will separate from the steel and float on top.  It seems that your steel would benefit from adding both Calcium and a bit of Manganese.

 

So your ingot is slightly cold short (cracks when forging too cold) and hot short (cracks when forging too hot) so you really need to remelt with some shell and a bit of manganese to get those two levels down.  You can reduce sulphur a bit through long high temp roasting in iron oxide but you will lose some carbon and you don't have much to lose in this ingot... so manganese is your friend at this stage.

 

I would avoid going above 0.5% Mn, you can go to 0.9%Mn but at those levels it darkens the steel background and masks the vanadium carbides. It makes the blades more hardenable but there is a pattern trade off.  Even with lower levels of manganese you will still get dark lines of manganese in the pattern being visible.  It doesn't take much, perhaps even 0.1% to be visible as dark shadow lines in the pattern going across the vanadium pattern.  But it is better to have some manganese lines than to have hot shortness.  As I said I would suggest that you need to deal with the Sulphur by adding up to 0.5%Mn. 

 

You can use the steel as it is with the additions and have success without diluting the steel, but you will need to remelt the steel. I would add just a smidgen of carbon back in just to make up for what you have lost in forging and oxidation in the forge.  Take the cracked ingot portions and remelt them with Calcium oxide and with Mn and I believe you will have success. The levels of Phosphorus are not disgustingly high, because even higher amounts were found in Ottoman blades of the same carbon content.  But you have to deal with the Sulphur and the Silicon which are both too high.  The benefit will be you will lose some Phosphorous at the same time.. Happy days :)  

 

Be aware with these analysis levels you will be getting an Ottoman kind of pattern. You can see now the benefit of getting a good analysis of your materials. With a bit of good advice you can get a good result without all the shooting in the dark that the ancients had to do.  All the best and please document what you do and continue to share it with us all.

 

 

 

Edited by Tim Mitchell

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I'll also throw out there that from the perspective of steels, not necessarily wootz, one of the biggest problems with S in steels is MnS.  I wouldn't worry about he Cu level you have.  

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Jerrod, adding Mn to steels is the old fashioned way of removing sulphur from the melt, and obviously it wasn't perfect or the Persians wouldn't have gone to the expense and bother of getting their ingots from India.  Can you shed some light on a better solution... other than don't have sulphur :D Also perhaps you could add some information from your expertise on the negative effects of MnS on steel.  

 

Ditto on the copper it isn't an issue and many blades had significant levels of copper, it acts as a hardener in small levels and adds toughness to a point.

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Sadly no, I do not know of a great way to remove S, unless we want to start getting into AOD/VOD territory.  Mg and Ca can both help.  Those sulfides will float well, and what doesn't float out is often a better shape (rounder) to be in the matrix.  This also brings up the question of how historically authentic one wants to be.  

 

I should have also mentioned that FeS is also very bad.  I guess I figured that was obvious, and just wanted to note that MnS is also bad.  MnS really starts to make things more brittle, so reduced ductility and impact toughness.  If you are lucky these sulfides will float out, or possibly forge out.  If unlucky, they will kill the mechanical properties of your steel.  FeS will be a problem no matter what.  If at all possible, sourcing materials that don't have any S in them is ideal.  If not, mitigating it may be your best bet.  

 

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There is "ideal" and then there is "adequate". Nothing matters till you reach a break point in use for the material. We all strive for the "best" and we tend to vilify the adequate.....all the steel has to do is get shaped into a blade and to blade things. You would be surprised at what that really requires. The MnS, Phos, carbide etc levels will only make brittleness noticed is the blade chips or breaks..........much like a crush panel in a car....only crumples when hit too hard, not in normal use. Ric

 

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