My initial journey into crucible steels.

[Daniel Cauble]

Btw, my original assertion was that the steel was 1.7%. Which is reaaally close to the 1.64% C it tested as. This is vindicating.

 

Also i would love to share the results of the suspected cast pucks but will put that in hold until something is written up.

[Joshua States]

Rock on Brother. 

[Tim Mitchell]

On 11/4/2018 at 7:56 AM, Daniel Cauble said:

My most recent work. ~1.7% C

 

Thanks for the analysis of the steel Daniel, that makes things a bit clearer.  The low levels of Carbide Forming Elements in the steel can do some strange things with the patterning and copper can also change things in the ingot... Nickel and Copper are actually your greatest CFEs in the analysis by a long way... very curious.  It is possible that the two part patterning that you are getting is as a result of these two ingredients, at least in part.  I do have a question to you though before I talk more about the final blade pattern.  These pics that you shared about the 1.7% inogot... were they pics of the raw ingot surface or if not, what was your processing to get it to this stage?  I know what my eyes are telling me but knowing what you did to the metal to get to this stage would help to know for sure. 

Don't feel bad, you have produced some really nice looking steel here, and the fact that it is different means that there is something to learn from it.  learning is always good.

Edited April 6, 2019 by Tim Mitchell

[Jerrod Miller]

On 4/5/2019 at 9:34 PM, Tim Mitchell said:

Nickel and Copper are actually your greatest CFEs in the analysis by a long way

Well, let's not forget iron, which is definitely the most prevalent carbide former here.  Ni and Cu don't really like to form carbide all that much, and iron loves to.  

[Tim Mitchell]

HA HA... yes well the iron carbide goes without saying.  We don't normally talk about the Iron Carbide as a Carbide Forming Element because it is not an element that gets segregated in the Inter-dendritic regions.  Iron carbide doesn't cause the patterning that we see in Wootz, that is from the other carbide forming elements. 

Ni and Cu are not really good CFEs and that is why I thought it was interesting, also as far as I know they don't exactly mix very well with iron or eachother. They don't become homogeneous and that may be one reason for the dark shaddowy patterning in the background.

 

[Jerrod Miller]

20 minutes ago, Tim Mitchell said:

as far as I know they don't exactly mix very well with iron or eachother. They don't become homogeneous and that may be one reason for the dark shaddowy patterning in the background

They mix exceedingly well with each other (check out the NBi-Cu phase diagram), and they replace iron atoms well in the matrix.  They are both austenite stabilizers, too.  

[Tim Mitchell]

5 hours ago, Jerrod Miller said:

They mix exceedingly well with each other (check out the NBi-Cu phase diagram), and they replace iron atoms well in the matrix.  They are both austenite stabilizers, too.  

Well there we go... it just goes to show that I can't remember everything.    I do recall that copper can combine with iron up to around 4%, but has problems combining after that, but that it is hardened by the presence of carbon so can lead to brittleness if it is too high in a high carbon steel like this.  At 0.1% it would contribute to hardening of the steel for sure. The copper would still be segregated to a reasonable degree in the IDR though, am I correct? Seeing it is a low temp melting element.  Any copper alloy in the IDR I would expect to show up darker than the pure iron dendrites under an etch like we are seeing in this picture.  I did some heavy research on Copper some time ago but I can't remember all that I read.... would have to check my notes. Copper is an interesting element in Steel and Iron.  Nickel is one I haven't done much research on at all.

[Jerrod Miller]

16 hours ago, Tim Mitchell said:

The copper would still be segregated to a reasonable degree in the IDR though, am I correct?

Depends on how things cool/solidify (or in some situations, how they melt!).  Generally speaking, all elements besides iron get concentrated outside of the forming dendrites during solidification of cast steel.  But things start to get a little weird when you have more things going on, like during a smelt.  You can never look at just the melting point of a single element.  You have to take into account the eutectic point of the given elements, which is hard enough to do with 2 elements, let alone several at the same time.  

[Joshua States]

Oh Boy. As if I weren't confused enough as it is. 

Does it matter if the "smelt" is in a closed system like a crucible rather than an open one, like a furnace? 

[Tim Mitchell]

I think that Jerrod was meaning "Melt", not "Smelt" which implies a direct ore reduction.  Making crucible steel in a crucible in a furnace is usually referred to as a "Melt" whereas making Iron in a Bloom Furnace is called a "Smelt".  There was a kind of wootz that was made in an open bloom furnace by remelting cast iron prills from the bloom process into an ingot in a quartz grit lined furnace floor.  This was done in Salem and possibly elsewhere in India by a specific caste.  When the iron had cooked off enough carbon it would solidify in the bottom of the furnace and then be removed and cooled. It is unknown if this produced a significant pattern or not. 

These ingots fit the description of ingots that were seen by Abbott and also the ingots that were sent to Faraday and Mushet.  Abbott's account seems to indicate that they are the same ingots made from the same process as described in Salem and they did produce a pattern. It was not uncommon to have quartz grit in the underside and a more ductile region on the top as described by Mushet.

[Jerrod Miller]

No, I meant smelt.  I don't really consider things happening just in a standard melt to be too weird.  During a smelt there is much more weird chemistry and other interactions going on.  I wanted to include that as this is the Bloomers and Buttons forum.  While there are certainly interesting and complicated things going on during a crucible melt, there are fewer things happening than during a smelt.  

[Tim Mitchell]

Right you are Jerrod! Thanks for clarifying.  I agree that smelts are very complex with more variables and unpredictability than a crucible steel melt. 

[Daniel Cauble]

Same blades, no change in finish. Just got an inverted metallurgical scope an testing it out. The 800x objective is being funny so not using it yet.

Remember, Ferric etch.

Still waiting on SEM results of this steel.

[Daniel Cauble]

800x.

[Charles dP]

Cool Daniel. Would you mind explaining what it is that I can see?

[Daniel Cauble]

Finally proper etchant this time, with other regeants on the horizon for different structures. I'm taking pics through the eye piece so they arent perfect or particularly crystal clear but you get the idea.

50, 100, 200, 400, 800, 800+optical zoom

 

[Conner Michaux]

What exactly is crucible steel?   I’m guessing something to do with melting, and foundry’s. 

[Jerrod Miller]

15 hours ago, Daniel Cauble said:

Finally proper etchant this time, with other regeants on the horizon for different structures.

Oh come on, you can't leave it at that!  My default would be nital, what do you have here and in mind for future use?  

Edited May 15, 2019 by Jerrod Miller

[Alan Longmire]

15 hours ago, Conner Michaux said:

What exactly is crucible steel?   I’m guessing something to do with melting, and foundry’s. 

Look at the pinned topics.  

 

There may be no dumb questions, but there are lazy ones. 

[Daniel Cauble]

50 minutes ago, Jerrod Miller said:

Oh come on, you can't leave it at that!  My default would be nital, what do you have here and in mind for future use?  

Picral, and then another that I dont have a name for that is a mixture of ethenol, picral, nitric and HCL.

 

The picral will help bring out cementite and leave ferrite alone. The other mixture should show grain boundaries.

[Jerrod Miller]

That is ... aggressive.  I look forward to your results.  

[Alan Longmire]

Be careful with that picral, that's some nasty stuff!

 

[Daniel Cauble]

9 minutes ago, Alan Longmire said:

Be careful with that picral, that's some nasty stuff!

 

I just made my own Nital with 68% Nitric and Methanol. yikes!

 

Will do.

[Jerrod Miller]

2 hours ago, Daniel Cauble said:

I just made my own Nital with 68% Nitric and Methanol. yikes!

My best results are typically with about 8-10%, when generally looking at steel microstructures for phase determination (pearlite, martensite, etc.).  

[Daniel Cauble]

1 hour ago, Jerrod Miller said:

My best results are typically with about 8-10%, when generally looking at steel microstructures for phase determination (pearlite, martensite, etc.).  

WOW! 10%?? Does this enhance grain boundaries? I cannot get them to show in this folded orishigane for me. My Nital is more like 3.5%. This time I lightly knocked off the oxides with 12k grit paper, etched for 25 seconds, knocked off oxides, reached for 25, etc for about 4 goes. Enhances the sharpness a little bit, but no hope of etching deeper into the boundaries. Sigh

 

400x

Edited May 15, 2019 by Daniel Cauble