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Tomislav Sokac

San mai headache

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Hello everybody! My name is Tomo and I'm from Croatia. I've got a problem with san mai (and my english but that's something you cannot help me). I've welded some billets using mild steel for cladding with 1.2519 core. I draw out the billet and hit it on sides and everything seems to be solid. Then I started forging a knife. Everything goes well with forging in the point, bevels and tang. When I finish straightening on lower temps I go to normalization temp and when it cools down the parts of blade starts to delaminate. This happened on 4 of 5 blades (one was successful and I don't know why). I'm using my power hammer (gently) for drawing out the billet and 80% of forging process. The steel was clean when stacked, welding temp in my gas forge was between 2200-2300 °F. Is it a problem with lower temperature (1650 °F) when I'm straightening everything or something else. I hope someone can help me. 

Thank you!

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Hi Tomislav,

Just had a look at the composition of 1.2519. Looks like it has 0.3%M and 1.2% Cr! Likely your mild doesn't like that a lot and also likely means that the mild is moving significantly more during heating and cooling cycles than the core, causing it to tear itself apart. I don't know what other carbon steels are available to you where you are but I would try another lower M and Cr steel. 

James

 

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Hi James! Thanks for the quick response. Yeah I know its a tricky composition (simmilar to blue #2 steel)for welding with mild, but people are doing it with success, so I gave it a go. I will not give up. We will see if the one that stayed welded will survive the quench. In my country there is apsolutly no steel selection to buy in small quantity for knife making, but luckily we are in EU so I order steel from Germany.

Thanks,

Tomo

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Approximately what temperature are you forging at? You said what you were welding at and then a lower heat for the finish forging, but are you doing the primary forging at welding heat or the lower one? My guess, and it is only a guess, is that you want to do most of the forging at welding heat and almost no forging at the lower heat.

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Hi Joshua,

 

 

I do the primary forging at around 2000 °F and don't go lower than that till the finish. I think that you may be right, because the one that didn't delaminate I kept at high heat, few strikes and back to the forge. I've read in some older posts that there is benefit in cold forging and that the nickel layer helps to keep everything together. I water quenched one of the blades that had minor delamination and it didn't open up, that is another thing that I've read in older posts, that fast quench is better for san mai. I've got some billet left, one with mild steel cladding and one with mild steel and band saw blade damascus, I will try to forge it at higher heats and see what happens, but after the new year. I'm a capricorn and they say that 2019 is our year, so I will take some help from the stars.

Thanks for the advice.

 

 

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