Need advice on heattreating

M

Marcel J.B. Morin

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Sep 17, 1999
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602
I did my first heattreat on Saturday and don't think it came out right. I heated the oven to 1450, put 3 blades of 01 steel in and let them sit for 45 minutes. Quenched in 160 degree veg. oil. Tempered at 450 twice for 2 hrs. each time. The smaller blade seems to have come out allright but the 2 bowie blades seem to have a soft edge. Is there a way to fix this? Thanks in advance for the help.

Marcel
 
Sure, heat treat them again, O-1 is forgiving like that.

First put your blade in the oven at 1000, let it ramp up to 1500. 45min is way too long of a soak maybe 15 min to make sure everything is evenly heated.

I quench in 125deg oil and move them like your slicing through the oil to keep a vapor cloud from forming, which could insulate the blade and keep it from hardening.
 
Maybe the heat in your oven is not even. I had the same problem, the bigger ones' edges were not at the center of the propane oven while little ones at the center. The back of the oven had a cold spot I guess, bigger ones came out not hard enough. I purchased an electric kiln, now no problem like that...

What kind of oven is it: gas, electric ?
 
Cooking O1 is like cooking chicken, you want to make sure it is cooked all the way through....

I would say that 45 min isn't too long of a soak for O1. It is longer than it needs to be, but their are no repercussions for soaking O1 too long, and there are issues if soaked too short. I would suggest 15 min soak after the steel has reached temperature. Depending on the thickness of the steel and the amount of it in your oven, it might take 30 min to do that. 45 is longer than it needs to be, but you're sure to not have under done it. So no harm done there...

Assuming your oven temperatures are even and accurate, that leaves the quench. O1 doesn't need a super fast quench, so I would expect veg oil to work (though 160 sounds a bit warm), so I expect you're not agitating the blade enough during the quench (don't shake it side to side. Instead, move it up and down or back and forth rapidly, like you're stabbing or chopping with it). For a faster quench you can use mineral oil or ATF. Or, if you want to remove the oil as an unknown variable all together you can simply purchase a proper quench oil.

You're not edge quenching this in a little tray are you? That would explain it too.
 
Before you do anything else take the edge down a bit more. It is very possible that you have some decarbonation on the outside and that is the softness. Possibly its good underneath. 1450f is on the low side for hardening, my chart says 1450-1500. I have started using the high end when I HT. You should still be alright especially with the long soak. If it is still soft down a ways Nathan is probably right about the quench. Jim
 
1450° is a tad low in heat for 01. You need a soak of maybe 15, to 20 minutes at 1200°, to 1250°, then ramp up to 1475° minimum, or 1500°, and soak for 15, to 20 minutes. Then quench in 125°, to 130° oil, moving the blade as Chuck said. To get your best from the steel, you really need proper quench oil such as AAA, but as mentioned, 01 is somewhat forgiving. If you forged it, you need to normalize it before the HT. If you used stock removal, you can skip the normalize, but it will do no harm if you want to do it anyway.
 
Marcel,
Welcome to the club!!
#1 I would up your temp a bit 1450 is the low end for O-1, I would go with 1475 to start.
#2 Forget about heating your oil, is a pain in the ass and no reference I have found (other than from knifemakers) recommends it.
#3 rather than agitating the blade; agitate the oil to speed up the quench, this is how it is done in industry and it works. (a prpellor in your hand drill works great)
Hope this helps,
Del
 
There aren't all that many carbides in O-1 to require more than about 15 minutes .Excess time does promote decarburization. The warming of oil is a common practice in industry and it comes from the best combination of cooling rate and viscocity.Proper agitaion is essential !
 
i will try it again this afternoon. I believe I did not agitate the blade during the quench. Will make sure to do this. Also my oil was probably to hot. Will use cooler temp. on the oil. Will post this evening to let you know how it worked out. Thanks for all the help.

Marcel
 
I'm inclined to agree with the comments that there may be edge decarburization. You can reduce/eliminate this by using an anti-scale coating. It significantly reduces clean-up work too. On this blade do as ib2v4u recommends and remove some material (only takes a few thousandths) and see what you get.

Nobody has mentioned the temper. Are you sure your tempering temps are accurate? You're working in a pretty narrow temp range to get what you want, so make sure your pyrometer/thermometer is accurate in that range. My first year of making was very frustrating. The frustration dropped significantly after I discovered that the toaster-oven I was using for tempering had a 70 degree temperature swing. That was enough to make my heat-treats a crap shoot. My heat treats are much more consistent now that I'm using an accurate tempering oven. If you don't have a purpose-made tempering oven use your kitchen oven but get a high-quality oven thermometer to put in it as a double check. You WILL find that the actual temp is not a perfect match to the thermostat setting. You can get a decent oven thermometer for under $10 at Bed Bath and Beyond (no jokes!)

-Ben
 
Last edited:
Heat Treat - 1500 Degree ( One Inch Per Hour )
Oil Quenching - 125 - 130
Temper - 350 Degree ( 2 Hours )
Air Cool After That
 
Did a new heat treat on Sunday afternoon. Brought temp. to 1100 deg. Put the blades in and brought the temp. up to 1500 . Held there for about 20 minutes and when I took them out of the oven I quenched in 120 deg. oil . After they had cooled off, I took a triangle file and could still cut a groove in the edge with the file. Any clues to what i am doing wrong. Thanks again for any help you can give.

Marcel
 
Good Morning Marcel, after reading this thread and going over your technique (which seems correct) are you absolutely, positively sure you're using O1 ?



;)
 
Sounds to me like your treatment is dead on, assuming everything is working like you think it is. (Are you sure the oven temperatures are accurate? What colors are you seeing in the blades when they come out?)

Even with a sub-par heat-treatment, O1 should at least get hard enough to be difficult to file.

One of the things I observe is the way the metal sounds when you run the file over it. Hardened steel makes a brittle, glass-like sound compared to soft steel. Take an unhardened piece of steel and try filing it. How do they compare?

Does the file actually bite into the steel, or is it just scraping the surface a bit?

I have to agree that it sounds like you might not have O1...

Josh
 
If you did not have some sort of decarb protection, you have decarb. 20 minutes at 1500° will definately cause decarb. grind the edge area a bit, and check again with a file. I believe you will find the blade hard under the surface. PBC powder will prevent decarb.
 
David Wesner said:
Good Morning Marcel, after reading this thread and going over your technique (which seems correct) are you absolutely, positively sure you're using O1 ?



;)
Click to expand...

Good point. In order for any of these methods to work, the conditions or preconditions need to be "ideal"... which they may or may not be.
 
JoshEarl said:
One of the things I observe is the way the metal sounds when you run the file over it. Hardened steel makes a brittle, glass-like sound compared to soft steel. Take an unhardened piece of steel and try filing it. How do they compare?



Josh
Click to expand...

True!

I'll add that it's also helpful to have some well heat treated pieces of 01 of known hardness to compare to. You can also try using the edge or corner of the file instead of the flat. I've noticed that the flat will often skate, but when using a sharp surface with some pressure you'll see a bit more if the heat treat is off.
 
Maybe I'm a skeptic, but I always sort of assume that the conditions and or preconditions are less than ideal, in a bladesmthing context. You can eliminate some of the variables, maybe even most of the variables,… but you can never really eliminate all of the variables...

I generally tend to fall back on experience and testing. :)
 
Ya i would say check for decarb. because you might have a layer that's thicker then normal. you have the first decarb layer from the first HT then the secound layer of decarb from the second HT. I get decarb from my 5160 and i only soke the edge for 7-8 min at temp then quench in about 120f mineral oil. I can tell its hard but i do get some scratches from a file but if i file a bit then it stops biteing and just slides.
 
Any steel that needs more than just a few minutes of soak, needs decarb protection, or an edge that in intended to be reduced after HT.
 
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