Weird quench pattern

B

BKT

Joined
Feb 15, 2016
Messages
167
Can anyone tell me why I have these funny little bubbles on my blade after quench? 1084 in parks 50 at 1475ish.

1X32sNe.jpg
 
Did you use non-scale powder? the only other time I have seen anything like that was early on when a major overheated a pice of O1.
 
No powder was applied. It was hand sanded to 220 grit, placed in the forge, I used laser thermometer to measure temp. Took it to a little over 1475, pulled and quenched in 85* parks 50. I was thinking bubbles on the blade in the oil?

Seems to be a surface thing. I have hand sanded the blade to 220 and they disappear.
 
Those look 3-D in the photo. Are they just colors on the surface or actual depressions in the steel?
 
+1 for decarb... ive had this and some elusive shiny speckles show up on aldos 1084. I think it was due to poor heat control.
 
looks like decarb or burnt away metal :) i used to get stuff like that when i would lay the blade in a charcoal forge and not move it around while heating it up. how are you heating it ?
 
Looks like it was over heated, I have seen this on blades that are eyeballed for temp in a forge. Back in my early days my blades would get that look. It's amazing how off your eye can be in guessing temps.
 
Stacy E. Apelt - Bladesmith said:
Those look 3-D in the photo. Are they just colors on the surface or actual depressions in the steel?
Click to expand...

Seem to be only surface deep as when all the scale was ground away they disappear.

Totally possible I quenched too hot. I am using a small propane forge. Its only single burner open on both ends so I dont think the steel was overheated. Never got hotter than dull orange. I run it low when heat treating so I can bring it just to 1500* and it takes a minute to get there. However, my laser thermometer is not that accurate. Very possible it was quenched at 1550* or so.

I went ahead and ordered an Evenheat yesterday :)
 
I've experienced this on items that were dipped in a borax/water solution during grinding. The marks stopped happening when I started rinsing with plain water prior to HT.
 
My guess was that it was borax.

Have you have used borax as a blade coat or anti-scale. That makes a very similar look, as noted by Patrick. Do you use borax in other tasks that may have contaminated the blade ( welding and casting)? It could be in the quench tank and the hot blade dunked in got a light coating. Or it could very likely be on the forge floor from welding a billet and transferred to the blade in HT.

Other things that cause this are:
Chemicals or something on the blade from the sanding and pre-HT steps.
Metal or trash on the blade from forging with grit or contaminates ( especially filing and grinding dust) on the anvil.
The blade being magnetic from using a grinding magnet and having some steel dust/grindings on it.
Forging with scale chips and chunks on the anvil ( Usually makes an uneven pattern and usually makes deep depressions). I like to hit the blade with a wire brush when I take it out of the forge, and wipe off the anvil with a rag while the billet is heating back up.
 
Good point. There is surely borax on the floor of the forge. I dont *think* there is any in my quench tank as I empty and refill it each time but who knows that stuff gets everywhere. I did have a light coat of 3 in 1 oil on there.

I am thinking about scrapping it anyways since it warped pretty badly. Maybe I'll break it open and check the grain.
 
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