....ping..

M

Mike Arsenault

Joined
Dec 23, 2006
Messages
84
So I snapped my second attempt, no pics yet. Was wondering if you guys could point out my errors.

Blade: Hand filed nicholson bastard file Bowie.
11" BLADE OAL 17-18"

Quenched in water non-magnetic at 1450-1500 from oven.
Tempered to bronze, then again 1 hour later to medium straw. (380 and 325 degrees, respectively)
1st tempering left for 1 hour
2nd tempering left for approx 1 hour (perhaps slightly less)

We snapped the blade while trying to straighten it using a vise, propane torch and spay bottle. I was applying the torch and bending force, friend applying water spray.
The blade had a nasty curve from the HT. I had normalized the blade once, quenched it with minimal warping, but it was full of soft spots. Being impatient and out of time for the day, we threw it back in without normalizing and quenched again to full hardness, but got a pretty nasty bend.
I tempered the day after the quench. It seemed awfully hard still after the tempering. The blade snapped near the tip (lost about 2 inches) while under bending stress, but certainly not enough stress that it should have broken if it were a usable knife! (probably only a 5-10 degree bend, or less, just enough to straighten.)
My instructor, and many others, have lost thier faith in the file steel, and claim it is too brittle to make good knives. I'm not so sure, as I see file knives and W2 knives here all the time... I hate to give up.

Any thoughts?
 
Water quench = ping. Even if it does not show visible cracks it will have stress points that will weaken the final product. If the blade is small and or thin it must be oil quenched, if it is a larger blade I like to do a interuppted quench with anit freeze preheated to 180 deg, it is much slower than water but faster than oil. 2 sec in, 2 sec out, 2 sec in, 2 sec out, 3 sec in, 2 sec out, 3 sec in, 2 sec out, 3 sec in, straighten if needed, quench till under 350 deg, temper while still at 350. Do not edge quench this way unless you like that ping. I use a digital lazer pyrometor to check the temp when I think it is getting close to to 350-400 deg. Also when I interupt quench this way I use a long narrow pan that only holds about 1.5 qts of quench fld, when the hot metal hits it, it will increase the temp. of the quenchent providing for a slower & slower cooling as the blade drops down to tempering temp. I use this method for 1095 and W steels where the blade is .200 thick and wider than 1.250 only!

Leon
 
There are lots of Heat-Treatment Experts here on this forum who work with W2.
They may need to know what tools you have to use, and where you got your file to offer you the best advice on what to try next time.

I dont know a thing about W2, but I have been reading on this Forum a lot over the years and you are not the first guy to snap a file blade...

If this last failed blade attempt is too much, then my only suggestion is to pick out a steel that can be Heat-Treated in oil,(perhaps good old 5160 car/truck leaf spring?) and do a type of HT that the Experts can suggest to you that will give you a blade that will not snap should you bang on it later to straighten.
 
Yeah, we already ordered some o1 for the second attempt. The water we used was preheated to the point of almost boiling (could barely touch it without getting burned). It wasn't an edge quench, it was a full quench in a 5 gallon pail. I'm not giving up on this metal completely, but maybe try some smaller blades with it next time..
 
Water is a very harsh quenchant. Even for steels listed as water hardening it can prove to be more trouble than it is worth.
My first suggestion would be get your hands on a very fast oil, such as Parks 50(Darren Ellis can help you there).
My second suggestion, if you want to keep quenching with water... Make a brine solution instead. 5% by weight works well(1 lb salt for 20lb water, about 2 1/2 gal) The brine will cool the blade more evenly than water, so there is less of a chance of cracking. I would also suggest quenching until all of the color has left the blade plus 1 second and let it air cool to room temp. When you pull it out, it should still be about 400-500 deg. If there is any warping, you can straighten it out before it finishes cooling.
I would also suggest tempering to at least 400-425deg

Good luck
Ken
 
If you try to bend a file,or a knife made from file steel, it will break.
As mentioned, temper was WAY too low.
Stacy
 
bladsmth said:
If you try to bend a file,or a knife made from file steel, it will break.
As mentioned, temper was WAY too low.
Stacy
Click to expand...

:D Now really, there is this super secret technique to get a file to bend....heat to critical and cool reallllly slow :P (it wont cut worth a damn though)
 
So when folks are clay coating for hamon, are they queching in fast oils, or is it always water? I got a 16" tanto blade (same steel) almost ready to normalize, and a can of mortar ready to go... was thinking of maybe (hopefully not) breaking that one sometime this week!;) :p :D one of these days i'll make this work...

The really annoying part is that these blades are all filework, no belt grinder... no knife to sell to pay for the carpal tunnel surgery...
 
I do alot of clay coated blades in W2 and I use Brownells tough quench which is a fast oil quench.
 
fast oil.

My thoughts on file steel is that it makes great files to file knife steel with. Use a known steel with exact HT specs. If you want hard and a bit of flexibility (and you like to hear PING now and then), use 1095. If you want hamon, try everything from 1050 to 1095 , and see what works best for you. If you want tough, use L-6.

As far as quench speed goes:
Brine is the fastest quench,then water, fast oil, regular oil, air.

Stacy
 
Anytime you try straightening a hardened blade you're playing the tough one.
Very difficult to do without compromise but can be done and if it snaps or cracks it is because there was a deficiency in heat treat or you stressed it beyond limit while attempting to straighten. Water quenching can be done without causing warp but water quenching is unforgiving - I should rather say too selective quenching whether water or otherwise can be the same. Tangs are easy. We don't care but blade edges must be protected from excessive temper during straightening. From the few but too many instances I have had to straighten blades I have learned to keep plenty of warm wet rags at hand and heat sink all of the blade except that very portion to be heated for straightening. I embed the blade edge heavily in clay and keep it moist to help prevent temper as best as possible. All this ugly concoction except for the clay encased edge is clamped in a vise. Wet rags and propane torch at hand and lights out so I can see the color of steel.

One nice thing about quenching, water or otherwise, it never hurts to do the heat treat over if the blade warped. Just heat the blade to about 1200 F for a few and good solid color and plate quench to straight and repeat HT. If doing a edge quench in water and the edge warps its back to the grinder or worse.

rlinger
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I have been thinking about this topic/problem with the way the steel snapped, and to tell the truth I have to call into question something.

There is something wrong with something here.
, if a blade snaps like this so easy.
It could be the steel?, the HT? the tempering??I dont know what it is.

But in the life of a blade there are going to come moments where a little bang from a hammer now and then is going to happen.
The idea that your knife snaps in two like this right at the start of it's life seems to me to be telling us that something very basic to the design or HT is going in the wrong direction.

I still use 52100 or 5160 steel and only harden the cutting edge.
I have had a bend out of the tempering that I noticed on a few knives about a year ago, but I just banged them back straight no harm done.

I dont see how I could ever trust a knife if just a little banging with the hammer to make it straight is so dangerious.
I could see it being a danger to a little blade, like a pocket folder, but when you got a big blade you should be able to treat it like it can take a good beating...

Part of the reason to make a nice big knife is the chopping power they have over smaller knives.
But thats a moot point if you dont dare chop with them knowing that they might snap on you.
 
Allan, the heat treat and the tempering are NOT two separate things. Tempering is part of the heat treat. It is true tempering is an item of its own but the heat treat is a complex which includes tempering, if tempering is incorporated. Heat treating encloses all aspects from such things as pre-heat to even cryogenics. It most certainly includes the tempering sessions as well. The heat treat is the entire window of temperature whether it be temperatures that burn us or temperatures that freeze us. It, the heat treat, is the complex of all involved.

rlinger
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rlinger said:
Allan, the heat treat and the tempering are NOT two separate things. ------
Click to expand...
a moot point,,,LOL
I believe that the HT and the tempering should allow the knife maker to end up with a blade that he can trust can take a bit of a beating.

This is, er, was a big whopper of a knife, and is something that has to be made with the idea that someplace down the line this blade is going to receive a few good hammer wacks from time to time.

The design has to be such that you can use the blade as you wanted when you made it.
Thus this is clearly a big chopper, so whatever else, we need to design into it an ability to take a hit.
And take it with no danger of snapping.
Im not sure what needs to be changed...
But clearly a knife such as this has to be able to be smacked straight without it snapping right?
 
Your base point well taken but don't you see that you are once again separating the two when in fact heat treat includes the tempering if tempering is performed. In this instance the tempering is a component of the heat treatment. It is not separate from the heat treatment. The foundation of this thread, as I saw it, is directed towards a heat treating problem. I could be wrong, again. How can you say "the heat treating and the tempering" like they were two individual components. They are not. Heat treatment is a complex of all temperatures used, high and low.

rlinger
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Mike Arsenault said:
So when folks are clay coating for hamon, are they queching in fast oils, or is it always water? I got a 16" tanto blade (same steel) almost ready to normalize, and a can of mortar ready to go....
Click to expand...

A clay coated blade can be quenched in water, BUT two things will help. first, try 1050, 1060, or 1075, the higher carbon content in a file steel may continue to give you problems if it is in direct contact with the water. The other: when you clay coat the blade, start by putting a thin layer (less than 1/16" ) over the entire blade, and then build up the clay over the spine and back half of the blade. the clay layer will act as a buffer, allowing a more even transfer of heat to the water, reducing warping and cracking.

One other note, as Stacy mentioned, using a known steel will help out tremendously, While some files are W2, others are 1095, W1, 1.22C steel, or a handful of other tool steels. Most are similar in heat treating, but different enough that one blade may work great, the next may crack.

Ken Nelson
 
Mike, good file steels (mostly 1095) and W2 are not too brittle when HTed properly. Use real quench oil and a fast one at that. Darren Ellis now sells them.
 
I quench my W2 in used ATF preheated to about 160 degrees F., and I've never had a problem bumping them back to straight on the ones that were slightly bent. I've yet to break a blade whether it is small or large with this method.

W2 is water quenched when made into a file for the speed of the quenching. It allows for very little retained austinite, which means that the vast majority of the steel will be extremely hard. It then gets a light temper to turn it into a file of about 70 Rc, which is way too hard for a knife. W2 can make a very serviceable knife, but must be heat treated properly with temperatures and quenchants that won't make it as hard as a file! I prefer to use oil, so that my W2 knife is between about 61 to 65 Rc before tempering. With a water quench I've found that the Rc is as high as 70, which is a very hard, brittle state, which requires a prolonged temper at about 425 degrees F. to get it down to a suitable using knife hardness. Just my thoughts...
 
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