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I guess I have a new learning curve to climb. The added stand created a cold area at the very tip of the crucible the cotton pad I placed on the bottom, before dropping metal into the crucible, did not incorporate into the melt. I may have also place the crucible a little low in the furnace and may have been too frugal with the propane as not all my anchor chain got incorporated...so it will be cut in half and remelted at 50% at a time  I will post some pics later. melting 1636 grams must take a little longer than 600 grams of metal.

Jan

Edited by Jan Ysselstein
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In planning the next melt(s) I have some serious problems to consider, the crucible showed a lot of tearing cracks indicating a great degree of shrinkage  ( I could see the height of the crucible getting smaller during the melt) . To assure a greater degree of melting I will boost the carbon content to 2.0% carbon by adding 800 grams of cast iron to the ingot. I am stuck with this particular crucible for about 8 more melts and will have to shift to a higher carbon content. now I should get a  2000 gram or a 2400 gram ingot ( that is good ). I will need to make a new furnace having the air/gas inlet closer to the bottom.

Jan

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OK that was 0/4 and I am taking some steps back to rethink this baby..I know what I want but am not sure how to get it. Si se puede.

 

Edited by Jan Ysselstein

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Steeping back was a good idea.

I am not sure what I am doing is realistic. The crucibles are holding up as I just melted an 1800 gram ingot. I took an optical pyrometer to my furnace and found I am running over 3000 F  at  way below my normal V setting...I was burning up crucibles for no reason (ouch).  I should be able to go over 2000 grams but not much more. Have encountered some beautiful microstructures and will post pictures after I write it up.

 

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So here is a picture of the 1800 gram ingot ( the goal is a large ingot to allow for a large forging, at least 2000 grams ). Also shown is a picture of a couple of 1600 gram ingots. One of the ingots did not complete the diffusion of carbon process.  Next step is to cut the  1800gram ingot to make sure the ingot is as sound as the other two. The microstructure image is of the large ingot. Very exiting stuff going on  .......... furnace , crucible handling and the microstructures seem to be falling in place.  I think I have to redefine the definition of "at heat " ...the four ingot halves were all put into one crucible and the crucible failed 15 minutes before the furnace was to be turned off.

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Edited by Jan Ysselstein

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he 1800 gram ingot looks very good . The mix was half homemade cast iron and half anchor chain. When cast iron was incidental to the bloomery process the carbon  content of that cast iron was  about 3.2% carbon....now I am targeting cast iron only as a product in the stack furnace and It looks like the carbon content is moving up and I will have to adjust for it. Now that I am getting more confident with the new crucibles I will not need to split the ingots anymore. All low carbon iron was properly incorporated by extending the "at temp" time. So 2000 grams plus ingot  is on the horizonzon. We will melt a few more ingots then move the crucible furnace to make room for the forge.

 

 

 

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Edited by Jan Ysselstein

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Dug up some cast iron and melted an ingot today ...looks really good ...;about 1450 grams .......the crucible was cracked but not all the way to the metal ( luck ). Here are some pics and I will be cutting it in half tomorrow. The crack was created by the  shrinkage of the low bisque fired crucible shrinking agains the high fired lid.

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Edited by Jan Ysselstein

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Today I did another run of the same material shooting for a lower carbon content ( which I may regret ) . I am on a mission to destroy my crucible furnace so I can switch back to placing a forge furnace in its place ( either one or the other not both )...it just will not die. The ingot is 1500 grams and should be 1.5 to 1.4 % C. I will be cutting both of these in half before forging.

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Edited by Jan Ysselstein
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Nice dendrites, Jan!  I hope they forge out well for you.  

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They should, though they look alike,  their chemistry is quite different. I seem to have run into a couple of forgiving crucibles. I did do a 2000 gram tall narrow ingot but did not hold it long enough at high temperature. I will run a few of those again this week. Now back to the Oct 4 post of last year looking for a way to make that pattern. That is not my ideal  pattern, I am hoping to finish up with a pattern showing at least some very recognizable dendrites ( or dendrite fragments 0.

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Posted (edited)

The little furnace is still going ...though the bore is getting too small due to frequent applications of kiln wash. Here is todays ingot 1.9 % carbon because I did not add all the ingredients ....but it looks good. All I have left now is a really low carbon run about 1.4% C . I think I have the melting process down .  Here are a couple of pics.  The 3 ingots are very different and should provide a mix of patterns.

 

Crucibles (2 of these) are ready to go ..after that I will take the furnace down after Cecil von Schwartz gets a chance...I have done some preliminary testing on that subject.

 

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Edited by Jan Ysselstein
addition of image

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Posted (edited)

I will not bother to post the ingot of the day..a few pits but all in all it went very well. Tomorrow is my last run and the forge will be back in place. All ingots will be cut in half , only one section of each will be forged. The ingots all have a different life history/chemistry and should provide some insight into the historical methods. The virus has me in the shop more than normal. Each melt requires 3 hrs of furnace time plus material prep. I am using my  homemade cast iron about 3.2--3.5% carbon. and a material called Norway iron ( an early steel from Sweden very clean just like wrought iron but no  slag and low P  ).  There is enough material on hand to do about a dozen more ingots. I am including some pictures from the early days when my crucibles were a bit thicker in the walls...( I will be going back to this type before leaving the subject altogether) . These pics are from 2006 or 2007.

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Edited by Jan Ysselstein
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The furnace died today...I will take a poker to the cast iron bottom on the inside ...if it comes loose, I try that last one again ( it is a valuable point for the data).  If that does not work, a forging we will go, lots of material to forge.

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Here are a couple of pics of the durable furnace which finally gave it up.  Looking back at why the crucible failed ...I would say it was too big for the furnace and heated very unevenly....when some of the surface got hot the stresses were just too much. I had never encountered that type of problem before so live and learn.

 

I have used that furnace shell to make a new one ( 2 hrs time including the demolition of the old one). This furnace will not last as long but I just have to get at least 1 more melt to complete my experiment with various carbon concentrations. I will post a picture of the new furnace when I get a camera in the shop. 

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