??? for the more knowledgable than me??

C

crank78

Joined
Dec 21, 2013
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and that almost includes everyone on this forum. what is the cause of this. it broke during some testing. glad I decided to test after ht instead of after completed fully. notice the two different colors in the break.
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Not everyone on the forum :p Wish I could help man but all I can do is give it a view and a comment. Coloration interesting.
 
im guessing that part did not get hot enough during ht. I tempered it for 4hours in 2 sessions at 425. this was the largest blade I had tried to date. kinda sad it failed but that's part of it I guess.
 
That's the only thing I could think of is the heat wasn't right at that part of the blade one way or another. That being said I haven't even started my first blade yet so I can't help much. I know I will be pretty upset if my blade turns out like this too, but like you said its part of the experience. All part of learning.
 
That dark spot is rust.

It means that there was a crack started there much earlier and it just kept going all the way.


What kind of steel did you start with, new known steel, or an old file ?
 
Quench crack....either too hot before quench, or quenched in too fast a medium.
 
Yep, quench crack. I had the exact same thing happen once. Why is this little section darker than the rest? Oh yeah, that's right where it cracked!!!!
 
Yes is was cracked before HT. Or it may have cracked during the quench and you missed it. Then broke when you were working it. Definitely cracked though.
 
It broke getting stabbed through 3/4 plywood. It made it through ok but when I twisted on it while in the plywood it snapped. I guess it cracked during the Quench. I guess I could have gotten it to hot.
 
Is that a hole that was drilled through right on the line of the break? If so, could it have caused some stress in that very same area?
 
From what I was told about 1095 and specifically water as a quench medium is that the water should be 150-175 degrees. Waters also not the best medium since 1095 needs a super fast quench, but I will be using water most likely myself.
 
1095 and W1/W2 are called water quench steel in the industry, but for the thickness of a knife blade, fast oil is more than fast enough. Cracking is a common problem with these steels without very good temperature control and quenching experience.

To avoid cracks, a thin wash of satanite will help.

Water is also only a term...brine is the actual quenchant.

Here is a past post of mine on the subject:
Brine quenching works very well.....about half the time. The other half ends up in two pieces of steel.

Brine quench is made up with 3 to 4 pounds of salt to five gallons of water. What you want is about an 8-10% solution. The old adage was, "enough salt to make the solution float a hard boiled egg." The blades are quenched in the warm brine, and if all goes well the steel converts into a rock hard martensite blade.....if it survives the quench and does not have the dreaded "PING", which is the sound of the blade tearing itself in half.

Parks #50 will get a good martensite blade with virtually no chance of the blade cracking or breaking in the quench. The final blade after tempering will be the same.

The only realm of brine quench is attaining the most active hamons, and getting sori on Japanese long blades. The steels used for this are very low in any alloy ingredients, and will survive the brine quench most of the time. 1095 has too much manganese and other alloys to brine quench safely.

With practice ( hundreds or thousands of quenches), a person will gain the ability to brine quench W-2 or 1095 with good results, but even a master will still break a fairly good number of blades. Most people are not willing to leave all those broken blades in the scrap can just to say, "I quenched this knife in brine."
 
I really wish I had the money for parks, but I know I am struggling just to get a two brick forge together to get started. After I have some money from selling some stuff, I plan on getting the materials to make a heat treating oven and some parks. Until then I am going to take the risk and get the experience. If I break some blades I wont be ashamed to say I quenched this in brine.
 
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