Hardening O1 Tool Steel - What Am I Doing Wrong?

I run the colors for simple pieces like punches and chisels. Polish the work and slowly heat the struck end until the business end turns a faint yellow to straw color. I usually quench and repeat the process to make sure that I have it right. For a piece that needs to be uniformly hard , that process wouldn't work.

One point about running colors. The colors are the result of the buildup of an oxide layer and there is a time dependency. If the work is left to soak at a particular temperature, the color will darken. If pushed too fast, the work temperature will actually be higher than that indicated by the color.

I have two laboratory ovens, one of them forced air convection, and both have widely varying temperatures depending on location in the oven. If I wanted to hit 300F dead on, I would use an oil bath for tempering. Our deep fat fryer will hit 360ºF. Lead baths were used for tempering springs in the past.

My Extech multimeter came with a thermocouple probe which is ideal for monitoring temperature. Mine only goes to 1382ºF but others go as high as 1800ºF. A thermocouple has a fairly linear voltage vs. temperature curve and are readily available on e-bay. A simple thermometer could easily be made using the millivolt function on a multimeter. A two point calibration could be made and a graph plotted to convert millivolts to ºF. Well known points like the melting point of lead or various solders could be used for calibration. One consideration with a thermocouple is that it is measuring the temperature against your environment. If the environment temperature changes, the whole scale shifts. Probably not an issue in your case but something to consider.
 
Excellent stuff guys, thanks for the responses. I'm getting ready to cut a few small pieces off the stock to run some tests. Probably do a few today so I can get this nailed down.

My wife likes to bake but she's not fond of following the recipes as they are written. When the item doesn't come out right the first thing I ask is "Did you follow the recipe?"

I just looked at the sleeve the stock came in and guess what; there's a recipe. I'm going to try that first and go from there. I do think I'm going to switch to ATF too. I have some here and from what I read it's better than motor oil.


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If you can control tempering/drawing temperature that's great. Color you have to be careful of. I make a point of polishing my work after hardening (cant tell what color it is when its black), then spraying it with steel ink remover to remove any trace of oil. The oil will turn brown long before the steel is anywhere's near the temperature you want, giving a false temper.
 
Attempt number 3 - followed the instructions

Heat steel to 1490±
Test with a magnet and it's not at all attracted to the magnet
Quench in oil - ATF
Check with file and it digs in a little but let's temper and see what happens
Once it's cool enough to handle it goes into the other oven at 400º for 1 hour - per instructions
Pull it out and run a file over it,... the file still digs in

Some observations. Even though the magnet is not attracted at all to the piece, it's only red hot at 1490. I watched a few more videos and most people seem to get theirs orange or white hot. I cranked the oven up to 1,600º to see what happens for the next try.

One more thing. At 400º, the part did not change colors at all. Very curious.

I thought the oven temp was off so I ran a test in between trials. Set the oven just above 1,200º and threw some cast aluminum in and after 20 minutes or so it melted. Temp setting seems to be fine.

Tempering is one thing but I can't even get the part to harden enough to be worried about it being brittle.


This is frustrating.
 
One possibility, it's not actually O-1. I had that problem with a supposed piece of ''D-2'', came out at a RC-35, when it should have been RC-65. I have no idea what the material actually was. The rest of the bar was relegated to the misc. pile.
 
I am starting to wonder. It was fresh out of a sealed package from the supplier but that's not to say they didn't screw it up on their end.

If it didn't have instructions that came with it I'd be a little more prone to say it's my fault but when I follow their recipe and it still doesn't work something sounds fishy.


This is the stuff I bought - http://www.travers.com/oil-hardening-flat-stock/p/73-016-096/

When I bought it 11 months ago is was under $11 but now the price is almost $40. Interesting there is a note on the page saying they don't sell oil hardening flat stock anymore. Maybe their cheap chinese supplier gave them a bunch of crap.
 
Couple of observations as I had a similar experience.

First, once the steel reaches the specified temperature you're supposed to hold it there for 15 minutes per cubic inch of material. I use 1550 degrees for O-1.
Second, 2 hours is way too long even at 300 degrees. For the product I used to make I used a maximum of 400 degrees for 45 minutes but it took some experimentation to hit the target hardness (verified by my Wilson Hardness Tester).

Third, I once received a bad bunch of 5/8" diameter O-1 from Enco, it would not harden no matter what I tried. After a phone call they sent me replacements that worked fine. It does happen sometimes. After that I started stamping ID numbers on both ends of the incoming bars then cutting 1" off the end of each bar and heat treating it (multiple samples at once) to ensure that I wasn't sent a dud.
 
ecdez said:
When I bought it 11 months ago is was under $11 but now the price is almost $40. Interesting there is a note on the page saying they don't sell oil hardening flat stock anymore. Maybe their cheap chinese supplier gave them a bunch of crap.
Click to expand...

From their website;)
Country of Origin: Import
 
I just double checked and saw it was TTC brand; definitely chinese and most likely garbage .

I finally had a bright idea and called Travers to see if they had a bad run and that's why they stopped selling it. They're all gone for the day but the lady who took the call said she'd have someone call back tomorrow. I think I already know the answer though.
 
Holescreek said:
Couple of observations as I had a similar experience.

First, once the steel reaches the specified temperature you're supposed to hold it there for 15 minutes per cubic inch of material. I use 1550 degrees for O-1.
Second, 2 hours is way too long even at 300 degrees. For the product I used to make I used a maximum of 400 degrees for 45 minutes but it took some experimentation to hit the target hardness (verified by my Wilson Hardness Tester)........
Click to expand...

Holescreek has it correct. Just because a magnet will not stick to the heated part does not necessarily make it correct to quench. Got to let it soak at temperature for a duration of time. Then pull and quench! And if you have to wrap the piece in stainless steel tool wrap heat and quench in the tool wrap. Just remember to remove the tool wrap from the part before tempering.
 
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