I think I know the answer to this but just to be sure...  I'm making a knife (sushi) with a hidden tang and the top part where the tang begins to form developed a crack (visible on one side, not the other)  I'm still in the forging/shaping stage. Is this something I can continue to heat and hammer the crack out or do I need to cut it off and just switch to a smaller blade?

My experience is that cracks don't hammer out.  If it were mine I'd cut off the cracked end and try forging a different design.    I'd also ask my self " What did I do to create that crack?"

I'd try grinding the down crack, since you said it doesn't go all the way through, see how far it goes.

Well, I'd start over.  A crack is probably caused by improper forge procedures.  If there's one you can see clearly there's probably more you can't.  Those will rear their ugly head later on.  Your not to far into this project, it's a  to get as far as polishing out a blade only to find cracks you didn't know was there.

Fatal? Yep, pretty much so. I have a drawer full of pieces that I'd really not like to discuss, and worse, no longer care to deal with. Someday, I may stack and weld them just because I hate to throw them away. Weld, twist, weld, draw out. What will be will be. It's the last chance saloon when you can't find a date.

John

It's not worth your time to try to fix a crack, because short of cutting it off and forge welding on a new tang, or cutting it up, stacking it, and forge welding it together into a billet, there isn't a way to fix it that isn't prone to failure. It will be easier and quicker to just throw it in the box of broken projects that everyone has in the corner of the shop, and forge a new one  and make sure not to hammer below a red heat so that it does not harden and crack again Or, if you were using scrap steel like leaf springs, it might have had a pre existing crack. Also it is my opinion that If you have one crack, there is probably another hiding somewhere in the steel that you can't see yet.

Forging a knife (sushi knife) and when forming the tang I got a crack. Can something like this be hammered out or do I have to abandon that whole end and do something else with it? Still learning and not afraid to learn the hard way, I just don't want to waste time and coal if it is futile.

This is leaf spring material from a truck.

thank you!

 

Sorry for the double post. Unintended

Ah sorry for the double post. Posted this first one from work and it said it was blocked for being a hacker site when I hit "submit". Just posted again with pics. 

Thank you you for the comments all

It is very possible that crack was already there.  Old springs often have hidden fractures. 

It is very possible that crack was already there.  Old springs often have hidden fractures. 

Excellent point.  All the springs I have at the moment were broken when I got them

It's like cockroaches; you may only see one, but...

Looks like the consensus has been "final rites". 

any problems with overheating it?

well... right before I noticed the crack I heated it to the point where sparks were flying off of it. I was trying to draw out the tang.

since its just a leaf spring & not a piece of Damascus you could Cheat & repair weld it

if you have a Tig welder & the right rod - you may see the repair area later when the knife is done ? depending

not something I do but its doable

I thought it looked a tad "crunchy" and overheating to sparking will often cause such cracking; I generally tell my students to cut at least an inch back from where it was overheated and re work.  

In general if I have a lot of metal to move for a tang I will think of cutting some off first to lighten the workload.

I would either cut it off or just start with another piece, but if you do try weld it with GTAW then try cutting a piece off of the same material and using that as your filler metal. That way there is no issues with dissimilar metals or the filler being inferior.