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another cracked blade

rocketmann

rocketmann

Joined
Dec 24, 2005
Messages
1,254
Well I cracked another one !!:mad: :mad: This one was forged from 1/4 x 1in 1084 that I got from Mace. I normalized it once..then heated to non-magnetic and then quenched in 125 degree oil. tempered at 375 for 1 1/2 hour.. The thing that gets me is that it didn't crack untill I had the handle almost finished (stabilized burl from grasshopper)!! :grumpy: I guess that I need to do several normalizing cycles and 2-3 temper cycles..:confused: I need to learn to not rush things so much..
 
How many times did you normalize while forging? Aside from only one normalizing it looks like you did everything right. 1084 is a very forgiving steel.
 
Your problem may be in the forgeing, although I would highly recommend the extra steps you mentioned in heat treat. It is just too easy to forge too cool for the steel. I don't forge, and in 35 years of knifemaking, I have had only one blade crack, and that was 16 years ago, with the second blade that I heat treated myself. It was a blade from a Toyota truck spring. You may also want to consider the quench oil that you are using, whatever it may be.
 
Rocketman,

It sounds more like stress risers from the forging than quench cycles. It's something to consider anyway.

Cracks from quenching usually show up immediatly.

Deforming from stress can come much later.

How thin are you grinding before you quench?

Grinding hardened and tempered steel is prefered by many makers.

Good luck, Fred
 
Louis, is the crack right in front of the ricasso at the edge? I can't see it, otherwise.....
 
A little better picture.. one crack is just infront of the ricasso, and another crack (with smaller cracks coming out of it) is in the center of the blade..The larger crack is hard to pick up on the photo..
 
If it had only been the "ricasso" crack, I'd have said maybe a stress riser from too deep a cross-scratch on the edge at quench. It is always a good thing to have the grinding scratches running lengthwise down the edge, and finer grit, at HT.

Seeing the ones in the middle, though, suggest to me the possibility it may be stress cracking from hammering too cold.

Don't know, but that's what comes to mind, Louis.
 
Thanks for the thoughts, The problem is that I have another blade that I forged the same day waiting to be ground out and heat treated..:grumpy: I don't know if I should bother with it or not...Mike I think that you may be correct about the cold working..Now that I think about it I did try to adjust it a little after it had lost some heat...stupid stupid stupid (I wish I was smarter).:o
 
Heat treat the other blade, Louis. Grind it and set it aside for a couple weeks after it's tempered. If it cracks, well, it's something to throw at the wall. :o

It won't be the last one, I promise. This is forever an imperfect endeavor and doodoo happens. :grumpy:

Save the failures...they make nice little "Post It" notes as a diary of what not to do again.
 
I concur with folks here. If you work it too cold, it'll crack every time. The tricky thing about those cracks is that they can be really small and hide until you're grinding down. I tend to work at a yellow for heavy steel movement (~2250-2300F according to my pyrometer) and then run a little cooler each heat once I've gotten the heavy work done. I'll NEVER work tool steel at less than an orange color until I'm just doing finishing heats to smooth out hammer marks.

I always normalize 3 times, and temper at least twice. I've only ever had one blade crack on me (it was the best for shape I've done to date too, and I didn't find the crack until I was buffing the blade....I keep it around to look at and try to duplicate). If you're using 10XX steels I believe you should also temper immediately after quenching.

Keep at it, and just make sure you pay attention to anything you do differently each time you're working on stuff. That way, once you get that "perfect blade: you'll be able to duplicate it. :)

Good luck!

-d
 
Did it really crack later or did you see it later ?? Tempering should relieve the stresses. Is the tempering temperature acccurate ?You could increase tempering time and do it twice. You might anneal, then normalize .
 
Those cracks are from cold forging I think. I am confident that they are not from heat treating.
Leon Pugh
 
Even the most "forgiving" steels will crack if hit too cold. I have created nasty cracks in both 1075 and 5160. I have a new forge and a pyrometer now so i can set the heat in the proper forging range (my slight red-green color blindness and changing lighting conditions where i currently forge makes it so i can't really trust my eyes to judge the color). That 1084 is Unobtainium alloy just like the W2 I got from Don. You want to minimize your chance of screwing it up............at least until you get to the grinder......lol
 
Is there any way to 'save' a blade you realize you worked too cold? Can you lessen the possibility of cracking by thermocycling the way you can if you overheat a blade?

I think i might have been working a couple blades from a coil spring too cold.
 
I have read stuff by both Kevin Cashen and Ed Fowler, who, as the Brits would say, are as disimilar as chalk and cheese on many topics, where they say that occasionally quenching while you are forging in addition to normalizing will atone for numerous sins. Unfortunately, the big cracks that appear during forging are there to stay. I am doing that now, but i am using W2 mostly, which has enough carbon that it can afford to lose a little from decarb from these additional heats and i forge pretty thick like Ed and J.D. Smith recommend. I don't know if the 1084 that has been for sale on here runs a bit thin in the 1/4 size like the Admiral 1075 does, so I'm not sure how thick you will be able to leave it. i'm starting with 5/16's to 3/8's on big blades that end up 1/4 on the nose or a little better when finished and hammering Ray Kirk's 3/4 inch round bar 5160, which spec'd out as having as much carbon as a lot of 1080, out to around a true 1/4 rough billet for starters for smaller blades. Even som, i still had a bad crack in the ricasso area of an itergral i was attempting to make from some of the 5160. Hit it a LOT when it was too cool for sure. When i noticed the crack, just for fun, i quenched it and then hit it on the anvil.......guess what? the blade snapped totally off right at the crack.....no surprise there. The entire areas that ihad abused has been stressed out.
 
Cracks that "appear" when polishing almost always were there all along. With the coarser grits they were burnished over. As you get a smoother finish the suddenly show up.As everyone has said, cold forging is a blade killer.With rare exception....Forge to black heat (when the dull red disappears) and put back in the fire.With some steels even black heat is too cold.
 
There is a big eifference between 'cold forging' and low temp forging.
Cold forging is a cool blade that you can hond in your hands.
Low temp is 1400 to 1625f.
 
Ed Fowler said:
There is a big eifference between 'cold forging' and low temp forging.
Cold forging is a cool blade that you can hond in your hands.
Low temp is 1400 to 1625f.
Click to expand...
at 1400+, the steel is still glowing rather red, isn't it?
 
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