first attempt at forging part 2

[Scott Fulford]

ARGGGGGGGHHH!!!!IT CRACKED
I cleaned up the hammer marks,profiled the blade,swiss cheesed the handle to make it blade heavy,applied funace cement for a wavy temperline.
I heated my quenching oil(vegetable) to 120 degrees,heated the blade to non-magnetic,then quenched it.It came out of the quench fine,I took the blade into the shop and with a 320 grit belt I began to knock off the last bit of clay and make a shiny spot to judge the surface color when it`s in the oven being tempered.Suddenly,over the whir of the grinder,I heard it,..."TINK!" It cracked right in front of me,from the edge halfway up to the spine,right in the middle of the blade.
What happened????????
The only thing I can figure is that instead of monkeying with it in it`s fully hardened state,I should have taken it directly to the kitchen oven,tempered it and then started to clean it up.
Any idea`s as to how I can avoid this in the future??
P.S. I had previously posted on this forum under the name "XxBossmanxX" from now on I will use my real name,
Thanx in advance for any help you can give me,
Scott Fulford

 

[Dementia]

there could be a few different reasons that come to my mind.

what metal were you using?

either way it is easy to say that the internal stress was just too much for the blade to handle and bing .. it went.
it could be that the blade had too much stress left over from forging the blade and couldnt handle it. did you normalize the blade? and if so .. how many times?

vege oil shouldnt have been a problem for the blade to be quenched in.. but maybe it wasnt at the temp. that you thought it was ?

just my thoughts for now.

D.

 

[Scott Fulford]

D.
Thanks for the help,I normalized the blade twice,and I had a candy thermometer in the quench tank...oh,yes and it was 1095
I really think I should have tempered it before I monkeyed around with it in my shop,as a side note,the yakiba temperline stopped the crack right at the point where the hardness changes.
Methinks I should try again.

My "Bubba" forge showing the $14.99 roofers torch burner

seems to work well enough

the camp knife before disaster struck,...it coulda been a contenda

The ill fated blade,and the next attempt on my ammo box quench tank
Anyone else care to take a stab as to what went wrong??
Scott

 

[ragnoor]

When I HT 1095, I triple edge quench after normalizing twice. I do not add the furnace cement or clay to the backbone of the blade. I proceed to the drawing oven immediately after the 3rd quench. I have had consistant results with this method, 58-60 RC.
KEN (WWJD)

 

[Epsilon]

A few likely possibilities (in importance first):

#1 - You did not immediately temper.
#2 - You overheated some section of the blade.
#3 - The oil viscosity was too thin.

I'm betting on #1.

Next time, just quickly remove the clay as much as possible and put it straight into the oven. Have the oven preheated first. Then after you put the knife in, allow ten to fifteen minutes for the oven to get back to temp. Start timing now. Do AT LEAST an hour. With 1095 I would do no less than 300°F (generally speaking). But play with the temper to suit your methods more importantly. A second temper is a good idea after it has cooled to room temp. It may require more tempers, but you'll just have to see how it does.

You could have simply overheated it. Break the knife in half. Check the grain. If it looks spotty or crystal-like, you did. If satin like, you were good on the heat. You might break it in a few places to be sure of your skill.

Lastly, the most remote possibility in your error. The oil temp may have been too great and caused the viscosity to be too thin, thus a faster than desired cool. I doubt it though. Try the temper, I'd put money on that one.

My thoughts.