What is this and how can I prevent it? (Heat Treat related)

Shaw Blades

Shaw Blades

Joined
May 18, 2009
Messages
1,831
Hello all,

I have recently started doing my own heat treat and have run into a little frustrating bit of surface ugliness. It is taking quite awhile to fully remove hence my posting. The steel is O1 quenched in room temp Parks AAA (60 degrees-ish right now). What are these spots and what can I do to prevent them in the future?

nwab68.jpg


Really appreciate your input and suggestions.
 
It never got hotter than 1475 degrees. I'm not sure there is much room for backing the temp off for O1.
 
Well the only time I've seen that on a blade is when I heat treated in my coal forge during the middle of the day. Made it hard to judge temp. Since then I heat treat inside or at night. No more problem. I'm assuming by your reply that you have a heat treat oven, Is it possible to verify your temps?

On a side note, I have that blades twin on my bench right now waiting for a handle lol.
 
Yeah I have a Paragon with a digital controller. One thing is for sure is that the blade was indeed hot.
 
well, in order of most to least likely, it would be Too hot, soaked too long, to fast a quench, or defects within the steel. Don't know any other possible cause, but no expert either. I'll be curious what input you might get.
 
Here is my exact ramp/hold

45 minute soak at 1250° for pre-heat (Full Ramp)
ramp to 1400° for 10 minutes to allow oven to soak a bit (Full ramp)
ramp (5000 degrees per hour ramp) to 1475° for 20 minute pre-quench soak (when I did this ramp at that rate it never went over 1480 before the 20 minute hold)
Quench in Parks AAA

Also I did 2 blades in this batch and the other didn't have those splotches all over it. The clean up only took a fraction of the time this one did.
 
I had spots like that before and I just chocked it up to thicker decarb. I leave a lot of stock on O1 now just for such reasons, and to help prevent distortion. Clean-up did not take too long with 40 grit belts though.
 
Big Chris said:
I had spots like that before and I just chocked it up to thicker decarb. I leave a lot of stock on O1 now just for such reasons, and to help prevent distortion. Clean-up did not take too long with 40 grit belts though.
Click to expand...

Good tip. I started with 80 after HT but I did take it a little too thin. Still trying to find the balance. Thanks.
 
Hi Michael. You need decarb protection. I use ATP 641, from Brownells. There is also a powder available, that you melt onto the blades. Both work well, but the ATP is easier to apply. You just paint it on and let dry. You also seriously need to warm your AAA to about 125° to 130° when you quench. Using the ATP, the blades come out as smooth as they went in. Leaving extra stock on the blade is just leaving extra work to do.
 
Use some decarb protection. A thin wash of Satanite works well. After the quench and basic celan up, soak in vinegar overnight. It should clean up pretty fast then.
 
I thought it might be decarb but I couldn't find any pictures that looked like what I had. Thanks everyone.

As a side note I found an old post where someone posted that Don Fogg mixed satanite with the ATP from Brownell's for his hamon clay.

This should be fun...
 
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