Heat Treat Soak options with propane forge question

Willie71

Willie71

Warren J. Krywko
Joined
Feb 23, 2013
Messages
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I have been working with O1 and W2 steel, and haven't had the time to build my electric kiln yet. I have used a muffle pipe with apparent success. I ordered a rockwell tester, but the deal fell through due to excessive shipping charges and hassles. I can't test myself because of this. Two nights ago, I was doing the HT on a piece of W2, and tried to use a flux rather than the muffle pipe. I used a water based brazing flux, thinned (in the unthinned state is has a thick syrup like consistency, and would likely block quenching like clay) with borax mixed in. I was able to get 12 minutes of soak before the flux started turning black (meaning its exhausted its capacity) and I quenched in Maxim DP48, heated to 120f. There was very little decarb, except the two spots I saw turning black, and the blade sanded out nicely. Does anyone have feedback on this type of procedure, pro or con? I felt I was better able to keep the blade evenly heated this way compared to the muffle pipe.
 
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You don't really want to shield the blade. A thin wash with clay would help prevent decarb, as will a coating of TurcoII.

I have no idea if your borax flux mix helped or hurt the hardening. It doesn't sound good to me, though.

The best methods for soaking are ways to provide even heat. Electric ovens are obviously the best. Gas HT ovens with muffles are the next. Forges of sufficient size and having a muffle pipe are good.

A PID controlled forge can be set to run at a very precise temperature and the blade can be soaked for 10-15 minutes without overheating or excessive decarb. Such a forge can do anything from HT to forge welding. There is a whole sticky on these devices.
 
Ive had pretty good luck with doing my 1095/1075/w2 and w1 with my forge. Oh and 52100 from aldo, ofcourse that stuff has such a fine grain already it almost makes it seem easy. Using a muffler has worked pretty good. If I am doing a hamon which I generally always will with the aforementioned steels except 52100 I will wash the entire blade with satanite (a watery mix just to make it grey). Then I layer on a thicker stuff for the hamon.

So I have a PID but not set up for a controller but I can still watch temps. I keep an eye on temps and check often with the magnet. I keep a close eye on the color of the steel. Once its nonmagnetic I watch that color closely. Just a tad brighter then do my soak. I keep a very close eye popping in every minute or so to check the color. A nice even color thru out the whole blade and as long as I didnt miss anything and let it get to hot it goes into the quenchant.

Ive had good luck with this and although I dont have a hardness tester my blades have performed well. I normalize before all this and temper afterwards according to the blade use. I have broke several blades after the quench and they have been very brittle, nice powdery grain structure.
 
OK, no more screwing around. I'll assemble the electric HT kiln before I do anymore hypereuctoid steels. For clarification, the flux mix was about the same consistency as the watered down clay, which I have used before. As I sanded and polished the blade, It appears I under-heated the tip a bit or the flux ran there and shielded it a bit, as the hardening line is closer to the edge than the clay was. The activity in the Hamon is quite nice. Its no where near what the pros are doing, but as a learning experience, I am happy with it. Its better than I hoped a first attempt would be.
 
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Hey Don was wondering do you think W1 can get by with a shorter soak also.
 
Quint, I haven't worked as much with W1, so I hate to say. But it is similar to W2, so I'd give it a shot.
 
Would it kind of depend on how your forge was set, if you had a O2 rich mix would decarb be more of an issue than if you had a bit of yellow flame coming out the door of the forge?
 
Yes, I have the yellow flame coming out the door :). Good to know on the soak. I can easily see W2 becoming my favorite steel. I did the last one at 1465-1470. I'll drop the temp a few degrees and see how it works. Are you guys using brine or fast oil for the quench?
 
I couldn't get the parks here, but got the Maxim oil, which is nearly equivalent from the threads I have read on it. I'm searching for a tester. Shipping to Canada is nearly $300.00 for a used tester. The portable ones may be an option if I can't find a bench model more locally.
 
If possible, make frends at a machine shop with a tester. They can check a blade or two for you.
 
I was thinking about that. There are a few machine shops in my area, and the steel industry is really big here. In terms of comparing to the "better" store bought kitchen knives I have for reference ($50.00 price range- I know junk compared to the good stuff, and the store bought hunters my friends used previously) my blades are getting a lot sharper, and holding the edge better. So far no reports of chipping either. I feel I really need to put some numbers to my HT to know for sure. I listed my rental property for sale today (should go up tomorrow online) and am negotiating the purchase of a new tester with the boss in the house :). To really guarantee the knives I am making, I need to be accurate with the HT, and verify it. The tester and grinder are the biggest obstacles I have excepting time and practice. I am really seeing the advantage of variable speed in grinding too.
 
Willie71 said:
I have been working with O1 and W2 steel, and haven't had the time to build my electric kiln yet. I have used a muffle pipe with apparent success. I ordered a rockwell tester, but the deal fell through due to excessive shipping charges and hassles. I can't test myself because of this. Two nights ago, I was doing the HT on a piece of W2, and tried to use a flux rather than the muffle pipe. I used a water based brazing flux, thinned (in the unthinned state is has a thick syrup like consistency, and would likely block quenching like clay) with borax mixed in. I was able to get 12 minutes of soak before the flux started turning black (meaning its exhausted its capacity) and I quenched in Maxim DP48, heated to 120f. There was very little decarb, except the two spots I saw turning black, and the blade sanded out nicely. Does anyone have feedback on this type of procedure, pro or con? I felt I was better able to keep the blade evenly heated this way compared to the muffle pipe.
Click to expand...

You didn't happen to be bidding on a Clark portable hardness tester, did you? Just curious. I'm in the same boat as you. I'm on the fence whether to send knives out for heat treat at Peters so they have a provable pedigree or try to sell the first large run with my own untested heat treat. I'm beginning to doubt that anything will sell that doesn't come without an accurate hardness rating. Either way the money from the first batch is getting rolled back into a hardness tester so I can develop my heat treat and provide real numbers with my knives. The local machine shop sounds like a really good compromise until I can afford a hardness tester.

Btw, Stacy, I found your DIY anti-scale recipe at this thread:
http://www.bladeforums.com/forums/showthread.php/670773-DIY-Anti-Scale-Compound?highlight=pbc+powder

I thought I might be able to save on steel foil by reserving it for normalizing at 1600+ degrees and using the anti-scale wash for the lower temperature soaks. About how many blades will that recipe last?
 
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I was bidding on a Rockwell tester that was used by the army. I won it at $500,00, but the shipping was crazy. It was originally $125.00 for shipping, then it had to be split to two boxes because of weight, then there were additional courier charges. We both agreed to scrap the deal at that point. I am looking at one of these, as shipping across the border on a bench model is prohibitive, and local searches have been dry: http://www.ebay.com/itm/NEW-PHR-1-Small-Portable-Rockwell-Hardness-Tester-Sclerometer-/271045578858

If anyone is curious re: the flux, two of the blades had a very thin layer that flaked off easily with a brief soak in water, but one of the knives I had in for normalizing pooled the flux to 1/16", definitely enough to affect HT. It shouldn't have affected normalizing though. The flux has a working temp range of 1400f to 1700f, perfect for this application, but it runs and that isn't predictable. If you are just looking to prevent decarb in normalizing, I think the water based brazing flux would be a good option. I got mine from a bicycle frame component supplier, but I think there is a prohibition to link vendors who aren't registered with bladeforums. If it isn't a problem I will post a link to the supplier. The flux turns glassy when heated, and comes off without chipping. Just soak it in warm water.
 
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