First San mai attempt

[J. Piontek]

This was my first attempt at forging san mai. As you can see it didnt go so well but thats ok it helps me learn. It was fine until i heat treated it, the steel is 15n20 on the outside with 1095 as a core. I think i may have just ground it to thin before heat treat the edge was .030. I know you guys have a lot more experience as I am still soaking up knowledge, what did I do wrong?

Thanks,

Jared

 

[Karl B. Andersen]

The pitting on that blade is extraordinary!!
Looks to be way over heated to me.
Other than that, I'd say the 15N20 is delaminating from a bad weld.

Hard to say by just looking at pictures and knowing nothing else of your process.

 

[J. Piontek]

The pitting on that blade is extraordinary!!
Looks to be way over heated to me.
Other than that, I'd say the 15N20 is delaminating from a bad weld.

Hard to say by just looking at pictures and knowing nothing else of your process.

I never ground the scale off the blade after forging so that could be why it looks pitted. Or maybe I did overheat it. I just ground in the bevels to see how it would turn out. then heat treated it to see if my welds would hold. Im kind of just experimenting still. After I heat treated it the 15n20 was peeling off so I ground it a bit to see what it looked like underneath.

The 3 pieces were ground to to 120 grit and tac welded together. I then heated them to cherry red in the forge and used borax as a flux. Then heated the billet to just under yellow, then slightly tapped with a 2lb hammer to set the welds. Then continued heating and fluxing until I felt it was welded. The I forged the knife to shape.

 

[Stacy E. Apelt - Bladesmith]

The welds didn't set in the middle of the billet.

This is a common first billet error. You need the whole billet at welding heat and allow it to soak a bit so the center gets to the same temperature as the outside. When you set the welds with gentle blows,start at the center and then the outside. This expels any trapped flux as well as sets the center first. After setting the welds, work it at welding heat from end to end several times, working from the middle to the outside as you go. Once the bullet is solid it will feel and sound like a plain bar of steel under the hammer. At this point you can drop the temps to around 1900-2000 and draw out and shape the billet into a blade.

 

[J. Piontek]

The welds didn't set in the middle of the billet.

This is a common first billet error. You need the whole billet at welding heat and allow it to soak a bit so the center gets to the same temperature as the outside. When you set the welds with gentle blows,start at the center and then the outside. This expels any trapped flux as well as sets the center first. After setting the welds, work it at welding heat from end to end several times, working from the middle to the outside as you go. Once the bullet is solid it will feel and sound like a plain bar of steel under the hammer. At this point you can drop the temps to around 1900-2000 and draw out and shape the billet into a blade.

Wow that explains why the welds in the middle didnt set and the outside ones did. I was starting more towards the ends on the outside and working my way in. Thank you so much such a simple answer and now it all makes sense. Thanks alot.

 

[dperk]

"This is a common first billet error."

This has to be true. I just made the same error out of the same materials and have a very similar test blade (last weekend).

I was using coal forge and was afraid to burn the billet, so I know I didn't soak it much. I'm going to try to re-weld the remaining 2/3 billet.

 

[Stacy E. Apelt - Bladesmith]

Go ahead amd try ... but once the first weld has failed, the chances of getting it to weld up is unlikely. This is due to oxides and other things that will prevent bonding.

 

[JMJones]

if you are using propane and the flux is smoking you are definitely at enough heat for the initial weld. Use lower heats after that but smoking flux on plain carbon steel indicates you are definitely hot enough. If using coal, charcoal or coke, it is easier to burn and I would try to weld before the flux is actually smoking because it means you are pretty close to the danger zone and these fuels can easily go past safe heat easily, propane is more forgiving.