Help with some not so scientific testing

scott kozub

scott kozub

Joined
Jan 1, 2018
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I'm new to this hobby and just finished building my heat treat oven. I made a few blanks out of .118 AEB-L from Alpha. I made 6 small coupons (3/4 by 2"). I wrapped each in foil with paper and heat treated to different temperatures for 6 minutes. I then broke the coupons, filed and hacksaw tested to see how hard they felt. I then put the remainder of the coupon in a dry ice bath for a couple hours and refiled and hacksawed with the following results. Each hacksaw test was 20 strokes.

I'm really hoping that someone more experienced could have a look and help me with what I should be aiming for as this is somewhat subjective. Here's my results. Sorry if the photos are a little blurry. The best I could do with my phone. There was a very noticeable difference after the sub zero.

Please note that each photo is at each temperature. The pre freeze is left and post freeze is right.

1955 Degrees - Pre Freeze - Very fine dull grain structure, could slightly grind with a file. The hacksaw cut in about 1/8".
Post Freeze - very fine dull grain structure, file just shined up the edges, hacksaw just barely indented the the corner, couldn't cut.
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1965 Degrees - Pre Freeze - Fine grain, some shine, less dull, Hacksaw cut in about 1/16th
Post Freeze - same grain, tough getting the hacksaw to start, very little rounding of the corner.
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1975 Degrees - Pre Freeze - Little courser but look very similar to 1965. Still mostly dull with some sparkle. Hacksaw cut in about 1/32
Post freeze - Gran looked the same, hacksaw didn't do anything
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1985 - Pre Freeze - Grain is getting courser, About 50% shiny, 50% dull, hacksaw wouldnt touch it
Post freeze - same grain, very hard, file and hack saw had no effect
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1995 - Pre freeze - Gran is course and shiny. very hard, no effect with file or hacksaw
Post freeze - same as above, can't test hardness
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2000 -Pre freeze - Gran is course and shiny. very hard, ne effect with file or hacksaw
Post freeze - same as above, can't test hardness

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The subzero step is pretty much a requirement for AEB-L to hit proper hardness and combat retained austenite. What I find strange is your grain structures. I have to wonder if maybe you’re temp is off or something. I am running mine at 1975 plus cryo and snapping them to find grain finer than any of the pictures here. Personally I would call everything but the first one fairly course, especially for this steel.
 
Grayzer86 said:
The subzero step is pretty much a requirement for AEB-L to hit proper hardness and combat retained austenite. What I find strange is your grain structures. I have to wonder if maybe you’re temp is off or something. I am running mine at 1975 plus cryo and snapping them to find grain finer than any of the pictures here. Personally I would call everything but the first one fairly course, especially for this steel.
Click to expand...

That's the input I was hoping to get. I may be too hot.

I don't know why but when I look at my post I don't see the pictures, just the img symbol.
 
I’m not seeing the pictures either just image tags but I can click on them and open them.
 
Scott basic members need to use something like imgur to host the pictures before posting
 
I would also say those look to have rather large grain. Here is a D2 sample I tested and this is under 30x magnification. You should not be able to see the individual grains with your eyes.

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Try lower temps, like 1925 and maybe 1940. Try to find someone to do actual hardness testing instead of filing/sawing.
 
Thanks for the help guys. I tried setting an off set on my pid by checking for non magnetic but it looks like I missed the mark by a big margin.

I appreciate the input.
 
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