0-1 HT trouble???

My ht always skates before the oven and when my "gut" says that was a good hardning. Are you saying that the file would hit the breaks before the 400 temper...or after

I was talking about after the temper. That's when you were getting the blue, wasn't it ?

Skate is a relative word. After temper it will cut the entire blade, but as suggested earlier, Use fairly light pressure and you will feel the drag on the soft spots.
 
blgoode said:
I also have 4 test pieces to get the RC tested on...hopefully tomorrow.
My mom works at a motor building plant and they have a RC tester :D
Click to expand...
One of them "Government Jobs" Eh?

Wondering, what sort of file would be best to have as a dedicated hardness tester. I imagine a single cut file between 6 to 10 inches.
 
these damn blades still came out on the questionable side for me...the RC test should say something to clear things up.

The same test blade did not chip out on the 2x's. I got it shaving but not hair popping and it shaved so so after a hard 2x4. What do you think....58 to 57 Rc? We'll see......that is if I didnt soften it up at the grinder :D :D
 
http://www.knives.com/heatreat.html

what do you think of the charts in the link?? Seems pretty good....

If I go by my color and use the thermometer as a reference this may be a better way to judge? I think 0-1 may do better with 1 -2 hr temper and one 1 hr temper
 
Gib,

From what I have read in my early HT research on tempering some say start @ x degree then in the next temper drop the temperature by 25 degrees.....

from what I have learned with trial and error it may be best to start out at a lower temperature and in the 2nd and 3rd temper increase to the desired color. Sort of ease into the right temper coloring. Does that make since or me just trying to trouble shoot as I GO?
 
Blues indicate you are way high in temperature. You are above about 500 F and you have tempered into 'blue brittle'. Your oven and/or the thermometer you use can not be trusted. It is simple: if you get blues/purples you are way above the 400 F temperature. You will now need to repeat the heat treat of this blade. Replace the thermometer and test both thermometer and oven using a sample piece of tool steel. Of course you know to keep the steel close to the position of the thermometer within the oven cavity.

Off the point but relative to the subject: have the tempering oven preheated and ready for the blade after quenching and when the blade reaches hand warm. Another way is to hold the blade in boiling water until the oven preheats to the desired tempering temperature. If not cryogenically treating I would temper at 400(+) F / 1 hour and second temper approx. 25 degrees below the first. If cryo treating I snap temper tool steels before cryo.

RL
 
Thanks RLinger. I got a second thermometer and they both showed the same temp by about 5 to 10 degrees. Do the HArbor Freight thermometers work well?
 
Another possibilty is that the colors are those remaining from quench. I sometimes have beautiful blues and purples even after tempering that were not caused by tempering.

HT a sample and place it close as reasonbly possible to the thermomter. Place the other thermometer at a remote location within the oven to check cavity consistancy.

RL
 
What type of affordable oven do you recomend AND where can I get a good thermometer? Target?
 
For carbon steels I use a simple toaster oven. They are small by design but I got the largest they had in the store. I bought a $3.50 thermometer and luckely they seem to work fine together. The steel will tell you and if your mom's place of work will Rockwell some samples you'll get a good idea where your temperatures are.

RL
 
right now I have a makshift sheild over my elements in the toaster....I'll hols it at 375 and see what color I get.

Thanks guys, I feel like I am getting to know the steel!! :D
 
the 2 thermometers i use in my big toaster oven i got from walmart in the cooking section, they are round metal ones and seem to work pretty well.
i put one next to the blade and on at the front so i can see it throught the glass door. they usually read the same, i did not put any shields around, i made a stand for my knives from a cut off coke can with a slot on each side so the blade is sharp edge down and spine up.
 
colors are those remaining from quench.

I hadn't even thought of that Rodger....Good thinking. It's second nature to polish it with an old stone before tempering.

If he didn't go in with a clean section of steel, It would be almost impossible to see true colors.
 
I have one more test blade going....

I polished part of the tang to measure the color by. Should I be polishing one part of the blade? I normally do both areas a little but if polishing a portion of the tang is pointless I'll just turn my attention to the blade. (I polished the tang because it was more soft)
 
I can't help on using different temperatures for the drawing back part of heat treating as I don't use that method. Almost all my knives are Bowie's with 8" to 12" blades and use a different temper. I heat treat after forging and before grinding. I use a electric cook stove with a oven thermometer and a piece of 5160 blade steel for a check of the temperature reached. This piece is ground clean for each session and is as thick as a bowie blade to give a similar response. Gib
 
Okay....test time.

The way I heat treated this blade was with an O/A torch. being careful not to over heat the tip making it brittle(right?)....

I was focused more on the choil area as its a little tougher to heat up so that area may have had more soak time.

the tip has a RC of 52.5
mid area is 55 to 56
and the choil area is 57.5.

IS the softer area of the blade where I babied the tip and tried not to over heat it? If so I learned a great deal from this test.

I did not baby the test samples and there pretty good....I wasnt woried about overheating them and just went by color of the steel to judge critical and then added about 5 sec, then quench.

There is one small one thats 53 rc ?? but here is the exciting part...

the other 3 pieces I did are
piece 1...57 -58
piece 2...57.5 - 58
piece 3...59.7

remember that I am judging this all by color ....I am just glad it is consistant for the most part.


As for the purples I was seeing.....I did not clean off the oxides from the quenching process so all color judgement goes out the window.(hey I had to learn the hard way :D )

The good news is that I did this small test blade and cleaned off all oxides. Its hard to see but I think it came out a nice yellow/straw coloring. What can you tell from it? With a file ,and my sample pieces at hand, I can tell it is in the good knife blade range.

Thanks for any input from everyone.
 
On your test blade: I presume the tests were after temper (how you can Rockwell the blade geometry at those areas escapes me unless you are using hardness testing files, but okay). Get the entire blade equalized in temperature. Your babying the tip prevented that. the mid section suffered as well. Concentrating more heavily on the thicker parts may be necessary to an extent. (O1, I think you are doing) Try to do it in the dark. Get consistant color from heat and, in the dark, you should eventually see shadows come and go. They will appear and look like cold spots to you. When all dissapear completely quench immediately within seconds after they dissapear. After tempering you should expect a hardness within the area of 58 to 59+.

RL
 
YEs RL its 0-1.

Sounds like im going in the right direction and not far off course.

Thanks for ALL the help RL....
 
You may best us propane. Strive to equally bring the steel to austenitizing slowly. Do not just blast the steel. Get it up moderately and equally.

RL
 
you got it. I went more slowly on my test pieces than I did the blade I think....I may have the hang of this soon :D
 
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