Bright flecks on damascus

F

FunkCoaster

Joined
Nov 2, 2010
Messages
172
Question on the image provided:

images%2Fknives%2Fjo4c02p5u1


There are odd 'flecks' of brightness at various spots. Especially 1/4 up from the cutting edge, inside the raindrop circles.
They seem quite regular and repeated, which makes me think it's not just irregular welds.

Any ideas on what causes this? My preliminary guess is that 'pocks' occurred during forging or heat treat, which exposed lower areas of 15N20.

Technical stuff:
26 layer 15N20/1084, with a 1095 core.
Hand welded/hammered over many forging cycles. Propane forge used. Decarb is likely, but a lot (~15%) was ground off the outer layers.
Stress relieved (1600, 1495, 1465) with a thin wash of satanite.
Rutland's black furnace cement was applied from the spine to about 2/3rds of the way down to the blade, terminating in a wave. Done to protect some thin regions that gave concern. The line is lightly visible in the picture.
Austenitized @1485, parks 50 quenched.

A test etch was done before hardening, and I don't recall seeing these 'flecks' at the time.
 
I have no answer for your question, but have a question of my own. Is that a type of skinner? Or?
 
When I zoom in, it appears it looks like the "flecks" are consistent across the whole blade, but they're bright on the lower third, which may be consistent with your claying of the blade.
 
R Randydb - Blade length is about 8.5". I'm calling it a 'camp knife' as a catch-all. For light tree limb cuts, rope, bushwhacking and the like.

D DevinT - Yes, tempered for 2 hours at 385F. Cooled to room temperature and repeated. The etching solution is FeCl, at about a 1:4 solution with distilled water. It is about 3 years old, but it doesn't see much use (maybe 12 total uses). Stored in a closed pvc pipe. Any guidelines on when solution needs to be refreshed?
 
Just some thoughts:
Random bits of alloying that are segregated (possible not a long enough soak or needed higher austenitization temp.)

Crystals of martensite or other structures in an area of carbon depleted metal. Somewhat similar to nie and nioi. (Too high austenitization?)

Pixies trapped in the steel that didn't escape in time before the quench. (Or possibly faeries)
 
Stacy E. Apelt - Bladesmith said:
Just some thoughts:
Random bits of alloying that are segregated (possible not a long enough soak or needed higher austenitization temp.)

Crystals of martensite or other structures in an area of carbon depleted metal. Somewhat similar to nie and nioi. (Too high austenitization?)

Pixies trapped in the steel that didn't escape in time before the quench. (Or possibly faeries)
Click to expand...

Och aye, the little people.
 
It is reasonable to believe it was overheated.

To further my understanding - would overheating mean too much time spent at forging/welding temperature? Or too high of a temperature at one point, regardless of duration?
No sparklers were observed during forging.

If it was overheated during forging, what would be the effect on the steel? Decarb?

I am perplexed as to why the decarb would cause a regular, discrete pattern.
 
I would first try to refinish and re-etch with sharp abrasive and new etching solution. Take it to a fresh 600 grit finish.

Hoss
 
I have had uneven looking areas on some damascus that I got taken care of by bead blasting it then re-sanding the high points with 800 grit ... followed by a final etch. A quick hand sanding with the blue 3M paper finished it up.
 
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