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Micro word of Wootz


Niko Hynninen
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More wootz...another bar starts to flow

..about micro structure...it shows spheroidized Cm / pearlite + free Cm in it

Ztoow i.jpg

Niko

 

Niko,

I do not remember ever etching this bar ( I do not even know what ingot it came from or why I did not ponder it at the time) , but here are some pics of an as forged and rusted..The pattern seems to be formed by slow corrosion rather than etching...this bar is about 17" long and has been on the shop floor under the forge for quite a while.....there should be another 1 or 2 in a bunch of coupons I have rounded up. The digital microscope was held by hand, so I took a pic of a cm ruler as well. It looks like fairly fine spheroidal cementite but I cannot resolve it....there is a crude thin, grain boundary cementite superimposed on the material...there seems to be only a little correlation between the pattern and the cementite in the grain boundaries.

 

 

 

 

Jan

 

Edit,

Played with the bar a bit, I do not think P is a big player in this bar ( it looks like it was easy to forge)..the other half still has to be heat treated. I am not sure the pattern is in exactly the same scale but it looks very similar

 

Jan

Edited by Jan Ysselstein
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Niko,

I do not remember ever etching this bar ( I do not even know what ingot it came from or why I did not ponder it at the time) , but here are some pics of an as forged and rusted..The pattern seems to be formed by slow corrosion rather than etching...this bar is about 17" long and has been on the shop floor under the forge for quite a while.....there should be another 1 or 2 in a bunch of coupons I have rounded up. The digital microscope was held by hand, so I took a pic of a cm ruler as well. It looks like fairly fine spheroidal cementite but I cannot resolve it....there is a crude thin, grain boundary cementite superimposed on the material...there seems to be only a little correlation between the pattern and the cementite in the grain boundaries.

 

 

 

 

Jan

 

 

 

Hi Jan.

 

 

I think its bit difficult to say much about stucture by looking at these pics, in some pics there might be GB Cm

 

Magnification if bit too low and grid too hard..Stucture looks more like segregation than actual Cm spheroids...

but to get more info about matrix, magnification should be higher + polishing about 1000..Nital whil show matrix quite nice, but looks like zag works even better.

 

 

BR

Niko

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Hi Jan

 

interesting... i've seen that rust n non/rust pattern aswell.. i think its more than just carbide resisting rust.. if there is abit of P, that may also resist the rust ... maybe

- so P areas and carbide will be brighter..

 

sometimes if you belt grind across the pattern, you should be able to see the carbide pattern in the bare steel..... often this is easily seen with no etch at all

 

Greg

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Hi Jan

 

interesting... i've seen that rust n non/rust pattern aswell.. i think its more than just carbide resisting rust.. if there is abit of P, that may also resist the rust ... maybe

- so P areas and carbide will be brighter..

 

sometimes if you belt grind across the pattern, you should be able to see the carbide pattern in the bare steel..... often this is easily seen with no etch at all

 

Greg

 

Greg,Niko

I do see the pattern at 1500 grit ( in general). Today I was playing with some coupons to get the maximum "look" for the particular bar. I will heat treat the above sample tomorrow..I think it will look quite different than the pics. ..this will be a radical change as I think I will be working with a low carbon steel.

 

Jan

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Jan.

 

Interesting images.

 

It might look like spheroids ( glusters more likely ) of Cm are sort of lined up to IDR and there is "impuritys" ( dark mater) in those regions too

long silver lines look like iron dentrites...but they should be pearlite matrix IF C level is as Wootz has 1,5 % ´is +/- 0,x %c..

 

But this could also be low C wootz...lower than 0,7%...so there then cold be ferrite and pearlite ( and pearlite has spheroidizied at those IDR...?? Hard to say from this magnification.

 

Whats the next plan for this steel?

 

Niko

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Jan.

 

Interesting images.

 

It might look like spheroids ( glusters more likely ) of Cm are sort of lined up to IDR and there is "impuritys" ( dark mater) in those regions too

long silver lines look like iron dentrites...but they should be pearlite matrix IF C level is as Wootz has 1,5 % ´is +/- 0,x %c..

 

But this could also be low C wootz...lower than 0,7%...so there then cold be ferrite and pearlite ( and pearlite has spheroidizied at those IDR...?? Hard to say from this magnification.

 

Whats the next plan for this steel?

 

Niko

 

Niko,

I assume there is more carbon in the bright areas maybe as spheroidal cementite and maybe a mix....I will try to bring more of it to the current large cementite lines and then try to break up the large cementite a little( maybe) .Now I know why it was under the forge as it is very coarse "net" wootz.

 

Jan

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Flow continues... :lol:

 

DSCN9589i I.jpg

 

DSCN9587i I.jpg

 

second sword blank out of 3 bars..next the 3 one

 

Niko

 

Niko,

That is a very pretty pattern...do you have a calculated Cr number for this steel?

 

Jan

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looks very stunning, Niko,

fine work :excl:

 

would have loved to see your work personally,

maybe next time

 

pysy terävänä!

Jokke

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Even I'am sober, nearly shi* my pants when look those watery patterns.

 

 

NHDaemon.jpg

 

Niko how did you make those own images with dendrites :lol: .

 

Absolutely nice work again, very encouraging for me, Thanks.

Do not try to forcibly, take willingly a bigger hammer.

Janne Kruunari
aka
B.Sofa


Also known as Jandaus Rahnasto
https://www.facebook.com/borderlandsofimagination

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  • 8 months later...

Niko,

 

I thought I would post this picture(s) under this heading. As I begin remelting ingots and trash, I take a last peek to see "what is what"...here is what I found in an old ingot

 

.

 

Jan

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Greg,

Good as remelt material...many of my "successful" melts have problems ..one of my last cakes is 50% voids. The use of ceramic crucibles is loaded with problems, the main problem is porosity, the other is you are working with two difficult processes ( firing a crucible and melting steel in it) and one has to finish before the other can really ramp up. I have a free weekend coming up and metal will be melted ( not 35 Kgs however).

 

 

It, the "what" is very good, I realize that .

 

 

Jan

Edited by Jan Ysselstein
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Hi Jan.

 

I think re melting is really good thing to do.

Its recycling and if steel had some impuritys in it...remelting makes it´s cleaner

...impuritys like slag, S and bad elements like gas....

 

About stucture.

 

If that is GB I thought it could be equiaxed dendritic stucture (Cm) or

Widmanstätten Cm. Was is like this all trough?

 

Niko

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Niko

This structure keeps coming up when the crucibles are porous and do not glaze so it is due to decarburization at a very high temperature, I assume it to be (Widmanstätten Cm) and that line to be a GB, though most in the area are much thinner and tend to straighter segments of GB forming a grain. I think somehow I am catching an unusual moment in the decarburization process of liquid or semi liquid metal....it does seem to be an efficient way to store carbon.

 

 

Niko,

The photo above is a look parallel to the plane of decarburization the photo here is perpendicular to that plane.You can see the proeutectoid Cm forming ( this was done at a much lower temperature however). Here we have a clear gradient in carbon concentration....... in a hot crucible with liquid metal sinking or rising who knows.

 

 

 

Jan

Edited by Jan Ysselstein
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Jan.

 

 

That looks interesting.

 

 

Can you polish this section more and re etch and re shoot it`?

Or have you all ready remelted this`?

 

Darker are sure is Widmanstätten Cm..but above that its just bit fussy to say.

It might be molten/semimolten hi consentration C are in you ingot...

There is slight dentritic stucture.

 

Niko

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