hardening problem

J

JasonByers

Joined
Feb 10, 2010
Messages
106
A week or so ago there were a few questions about making knives from farrier rasps. Its been a while since I've made a file knife and I got a little hankering after hearing the comments. I used to use black diamond brand files and was being supplied by a farrier friend. I guess those got expensive so he switched brands to Bellota??. Well I annealed one and cut a few pieces off and heated to 1500 soaked for 5 min and quenched two in oil and two in brine. They all snapped in my vise with little effort. Also oil hardened them just fine with no noticeable difference in the brine. Well I thought good to go. I cut out a blade, ground, normalized three times, heated and soaked for 5min at 1500, quenched in oil and when I tried to skate a file for a quick check it was still soft so I tried again in the oil with no luck. Then went to the brine and still it was soft. My heat treat forge was still at temp so I cut a piece off and heat treated it the same way and it snapped right in two and skated a new file. I filed into the edge of the blade about a 1/32" and finally hit some hard steel. What did I do wrong? What ever I did wrong the same thing happens to me and cable damascus. I have to forge to shape, heat treat then grind to get a good blade out of it. Thanks ahead for the help.
 
Thanks for answering Mr. Hanson. I don't think my edges are too thin but I bet your right on the soak time. I also thought I might be bringing my blades up to temp too slow. I heat treat in a small propane forge with a thermocouple and if I run the forge at 1500 and introduce a cold blade it takes around 15min for the forge to equalize at 1500 again then I start my soak. Is this too long? I never have had a problem with 1084 and 5160 before which are my usual choice of blade steel but I don't soak 1084 and 5160 I edge quench with a short soak. Thanks again.
 
Thanks Mr. Jones I actually just finished doing that and it turned out just fine. On this particular knife its no big deal, its for my horse shoeing pal I was talking about and I gave him a good price on it since I feel all unknown steel knives such as files and cable should be treated as sort of a novelty knife. It turned out pretty dang usable though. I was just wanting to know why the thick layer of decarb is happening. I'm sure Mr. Hanson has it. Thanks again.
 
What Don is trying to tell you is that the edge is thin enough that it is loosing its carbon in the heat treat. It may very well have lost a good portion of it in the forging.

Leave it thicker, and finish grind after the heat treat. The Decarb is just that. Carbon loss to the surface of the steel. If you are going to leave it in the furnace that long, use foil wrap. It will help.
The heat combined with the oxygen, is destroying your efforts.

Mike
Maker
The Loveless Connection Knives.
 
Ok thanks Mike. I'm going to shorten my time in heat treat and I'm sure that will help. If not I think I will bite the bullet and buy a good heat treat oven. Its over due anyway. Thanks for the advise.
 
JasonByers said:
Ok thanks Mike. I'm going to shorten my time in heat treat and I'm sure that will help. If not I think I will bite the bullet and buy a good heat treat oven. Its over due anyway. Thanks for the advise.
Click to expand...

Jason, I've had a Paragon for over 20 years, and it is still going strong!

Mike
Maker
The Loveless Connection Knives
 
preheat your forge without the blade in it, once it has reached thermal equilibrium put your blade in. You will overheat your blade trying to heat the forge up to temp with the blade in it and the extended burn time will give you deep decarb

-Page
 
I have a few more blades to heat treat this evening and I just finished grinding another rasp blade to go with them. I will take in all the advise and try this again. Page although I don't put my blades in when I fire the forge up I think your right. Even though my thermocouple is reading 1500 I don't think the forge is fully heated. Tonight I'm going to heat the forge up and before I put any blade in I'm going to let it run another half hour or so to level out. Till now I didn't think it made any difference. My wife is always complaining how she never knows what to get me for Christmas so I think a paragon just went on the list. Thanks again for the help.
 
Ok I just heat treated another file knife. I brought the forge up to temp and left it alone for 30min, normalized, waited 15min on the forge again and heated with no soak and quenched in oil. The blade turned out great this time. Huge difference. This was the first time I've experienced such a thick layer of decarb but all together I think it turned out to be a good experience. I think I will do a little bend testing on the other blade just for curiosity's sake and scrap it. Dmitry.M I'm sorry I'm not too sure what your talking about? Thanks for the input though.

I'm looking into heat treat ovens now and I think after the initial excitement of wanting one I've decided the Paragons are out of my price range with a baby on the way so I'm just about to buy a cheap Sugar Creek from USAKnifemakers. The only steel I ever use is 10XX, 5160 and the occasional 52100 so I'm sure this oven will do just fine, much better than my setup now at least. Thanks again guys for the help.
 
Order yourself some of the stainless heat treating foil. It will do away with "ALL of the decarb!

Even heat makes a nice oven at a much lesser cost of a paragon. Not as heavily built, but very accurate!

I've had my paragon so long that it cost me 475.00 New!:eek: Man, I'm getting Old!:rolleyes:


Mike
Maker
The Loveless Connection Knives
 
Try lowering the temp to 1475 as well. 1095 grade steels like in files need to be at a little lower temp than 1084 and 5160. It's the temperature I use with the edge about 1/16" thick and it works great.
 
Before he starts wrapping blades in foil I'd like a good explanation on getting 1095 out of the foil and quenched before he misses the nose of the curve. 1095 isn't real forgiving on 5-10 seconds before quenching.

You might consider a light refractory cement wash, Turco, ATP-641 or some other blade coating. Foil takes way too much time.

Gene
 
Well I already have my order in for the Sugar Creek. Thanks for the recommendation of the Evenheat though. I looked at those pretty heavy but decided to go with the small S.C. that wasn't programmable, only $388. Again I did not think I really needed a programmable model with the steel I use. I might regret my decision but my wife and I are about to have our first child so its got me a little shy about spending a lot of money. I did not get any foil because I a little scared of it but I will get some to try when I get my next order of belts. I have 5 blades ready for handles anyway so that most likely will last me till after Christmas. I will try 1475 on the next knife which will be from 1095. thanks.
 
Gene what about satanite? And how do you do this? I have tried a very light watery coating to help with clean up after the quench which did not work well for me but will this light of a coat reduce decarb?
 
I've used AP Green 37 as a watery mix but haven't been really satisfied. Turco can work fairly well for one blade. When I open the furnace door the influx of fresh oxygen seems to consume the Turco on any other blades, so I leave them thick and grind off the decarb.

I have to get some ATP641. I didn't know what it was until yesterday. Mike Turner came over a while back and used my Paragon furnace to treat some blades. He had a powdered version from Brownells and while application was a pain, the stuff worked like a charm. The blade came out clean, most of the stuff washed off in the oil quench, and what didn't washed off with water.

I do batches of blades at a time, mostly D2, ARS34, 440C or A2. That I can foil wrap. The 10xx series, O-1 and 8670 drive me nuts with grinding off scale. Turco hasn't been that great. Doing Japanese blades with a clay coat has worked some with a good light wash of cement, since I'll be grinding some of the clay off anyway.

When I saw that ATP641 comes in a liquid I was just overjoyed. Sprinkling powder on 500 degree blades didn't do a lot for me since the coat needed to be thin but uniform. It takes time and the blade is cooling, so it's just another challenge. Yes, it's clean, but doing several blades would be a study in frustration.

Brownells sells it, as does Knives Plus, according to Blade mag. I checked out the Knives Plus website and their search engine didn't show it. I'll give them a call next week and see what happens.

I've resisted salt pots because So Oregon is not known for its dry climate. From now until May it can be pretty damp and I'd just as soon not have a salt pot explode in the shop. My smithy is not fully enclosed and probably won't be as long as it's in the barn. I'll have four sides on by next summer, rather than two, but there is too much open space up high. When it isn't raining we can get a lot of fog. Salt loves water and would just suck up the fog or other moisture.

I'm going for it on the ATP goo. After the Rocky Mountain Knife Show in 3 weeks I'll have about 30 8670 blades to do. That will be the proving ground for the new stuff.

I'll keep you posted. I was grinding scale off 3 8670 blades today and it just gets old.

Gene
 
Thanks Gene, I'd appreciate it if you could keep me posted on the liquid ATP. Yep stories I've heard about salt pots scare me and I wouldn't consider them at all. Besides I have a basement shop and my smithy is just wheeling my equipment outside under the deck. Far from ideal but it will do till I get my shop built next year. Thanks again Gene. Good luck at the show and have a good weekend.
 
I don't like using mixtures and coatings. The fumes can in time, ruin your coils.

I have been using foil for over 30 years. I see no problem with using it with oil quenching steels. I simply remove the blade from the oven, snip the foil, remove the blade and quench.
The foil insulates the blade, and keeps it hot until I quench.
Easy really.

Mike
Maker
The Loveless Connection Knives
 
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