I tried everything to prevent this.....

colu41

colu41

Joined
Dec 24, 2014
Messages
1,598
I literally JUST read a thread on this the other day but, I tried everything that people were suggesting.
Rough finishing up 3 of my first CPM154 blades before I ship to heat treat. I don't know what else could have happened. But one of the 3 blades ended up with little tiny brown spots. I used new belts, and no magnets, so I dont see other metals being in there? Any other tips? And should I try grinding this off before I ship to heat treat?

Pic #1 - blade with spots. Pic #2 - just comparing to a clean blade in case the spots were hard to see.

2n0sbx0.jpg

5oc8w6.jpg
 
I suspect it is just water spots or something similar. Send them off and it will likely be gone when they come back.
 
Ok. I'll do that. Either way when they get back from HT, I'll most likely have to do a little finishing work. I might go up a grit on the grind also so, it should go away. Thanks Stacy
 
It's not impossible there is some trash in the steel. Crucible needs to step up their game, they're lagging.
 
Another thought. Did you grind the mill scale layer off before starting bevels? If not may still be some scale layer pits showing up.
 
I have had that problem with CPM S35VN. I suspect, but don't know for sure, impurities in the steel. Hope someone else knows what is going on or hope someone from Crucible will chime in.

Tim
 
I see it sometimes....usually from blades dunked in water while hogging bevels. It is just rust/oxidation spots on the surface as far as I can tell. Sources can be contamination from carbon steel, crap in my dunk tank ( Boy, oh boy, is that water/sludge ever filled with crap), and just normal rust/oxidation in pits and pores of the steel. As Kosa pointed out ... the steel will rust pretty easily until it gets heat treated. After HT I grind the bevels again from 220 up to 400 grit, and never see the problem, so I am sure it was on the steel, not in the steel.
 
There have been such problems before with CPM and Crucible should replace the material.
However it's hard to tell from the photo if it's ON or IN the steel
Polish it a bit to see if it's just a surface thing.
 
Don Hanson III said:
Are the brown spots a problem for ya? Blades need to be finished after HTing anyway.
Click to expand...

Well, I know I am going to have to refinish a bit after HT, I just wanted to know if for some reason there were impurities or "other" metals that got lodged in there while grinding, the HTing would so to speak "weld" in their permanently. But, either way, finishing up the grinds post HT should take care of it like everyone said.
 
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