Gun Blue on my ASH-1

Coupchoux

Coupchoux

Joined
Aug 31, 2004
Messages
767
Hi,

I've tried to put Gun Blue on my ASH-1 CG, but it doesn't work like on my SARsquatch... Both are INFI. I've used the same procedure, it works on the SARSquatch but not on the ASH-1. I don't understand why. An idea?


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Last edited:
tomthebaker said:
Because the Sarsquatch ( Comp. finish?) has a layer of decarbonized steel?
Click to expand...

The surface of the steel makes all the difference.The amount of decarb left on the blade can factor in as well as the surface finish of the steel. Depending on how open the surface is will determine how the blueing reacts. Looking at the ASH1 you can see that the surface is much smoother without pores or opening for the chemical to enter. the Sarsquatch has a very porous, open surface allowing the blueing to penetrate.



Garth
 
Can someone tell me what decarb is? I thought it was the stuff you used to spray in your carburetor before they invented fuel injection. :confused:
 
The surface of the steel makes all the difference.The amount of decarb left on the blade can factor in as well as the surface finish of the steel. Depending on how open the surface is will determine how the blueing reacts. Looking at the ASH1 you can see that the surface is much smoother without pores or opening for the chemical to enter. the Sarsquatch has a very porous, open surface allowing the blueing to penetrate.
Garth
Click to expand...


Yes, the ASH1 surface is much smoother than the rough SARsquatch :

http://www.scrapyardknives.com/ubbthreads/showflat.php?Cat=0&Number=197119&an=0&page=7

I think you're right Garth.
 
Guyon said:
Can someone tell me what decarb is? I thought it was the stuff you used to spray in your carburetor before they invented fuel injection. :confused:
Click to expand...

"Surface decarburization is a loss of carbon in the skin of the material. Favoring factors are high temperatures and larger quantities of oxygen in the atmosphere.
In the following some characteristics for a decarburization are listed :
1. Increased amount of ferrite
2. Reduction of the amount at carbides
3. Lamellar pearlite at annealed hypereutectoid steels
4. Worse etchenability at higher alloyed steels
5. Various amounts of the different microstructures
These details have to be understood as a change in proportion to the basic structure. "

http://www.metallograf.de/start.htm?untersuchungen-eng/entkohlung/entkohlung.htm
 
Well, I was just gonna say "Lamellar pearlite at annealed hypereutectoid steels"

but you beat me to it.
 
resinguy said:
"Surface decarburization is a loss of carbon in the skin of the material. Favoring factors are high temperatures and larger quantities of oxygen in the atmosphere.
In the following some characteristics for a decarburization are listed :
1. Increased amount of ferrite
2. Reduction of the amount at carbides
3. Lamellar pearlite at annealed hypereutectoid steels
4. Worse etchenability at higher alloyed steels
5. Various amounts of the different microstructures
These details have to be understood as a change in proportion to the basic structure. "

http://www.metallograf.de/start.htm?untersuchungen-eng/entkohlung/entkohlung.htm
Click to expand...

Ok - We now know what was done but ..... exactly what does it mean for the surface of a knife blade? An INFI knife blade? And why would you do it?? :confused::confused::confused:
 
TurnerIII said:
Ok - We now know what was done but ..... exactly what does it mean for the surface of a knife blade? An INFI knife blade? And why would you do it?? :confused::confused::confused:
Click to expand...

I don't think one does it on purpose, at least not for knives. It is a consequence of the heat treat process, and I think one would want to minimize it. Stripping too much carbon to too great a depth would likely compromise the blade's properties. I don't mean to imply that this has happened on the SARSquatch. steelnut posted that he was able to buff off the decarb with a light pass of a Dremel wheel.
 
It really does vary, The ASH-1's in general that I've seen stripped pictures off look like they were either protected during HT or had some finish grinding or abrasive blasting after ht. The decarb layer on my CGFBM (obviously NOT ground on after ht) was a bit thinner than a sheet of notebook paper, however it was also a real bear for me to remove, it took I'd guess a half hour of time with an 18v drill and a scotchbrite wheel to get it off, and I still have some in the corrugated bevels.

Decarb happens with all steels during HT, unless you use Salt pots or other non-oxygen atmosphere methods of heat treating. The effects on rust resistance/blueing are most noticable with the stainless steels, since decarb often nullifies any rust resistance. That's exactly what you're seeing here, INFI is by its nature very stain resistant, in some cases exceeding ats34 and similar high carbon stainless steels. The decarb layer (rarely removed on combat grade knives, never on comp finish blades) is more susceptible to rust and will take bluing far easier than the infi a few microns below it will.
 
yoda4561 said:
It really does vary, The ASH-1's in general that I've seen stripped pictures off look like they were either protected during HT or had some finish grinding or abrasive blasting after ht. The decarb layer on my CGFBM (obviously NOT ground on after ht) was a bit thinner than a sheet of notebook paper, however it was also a real bear for me to remove, it took I'd guess a half hour of time with an 18v drill and a scotchbrite wheel to get it off, and I still have some in the corrugated bevels.

Decarb happens with all steels during HT, unless you use Salt pots or other non-oxygen atmosphere methods of heat treating. The effects on rust resistance/blueing are most noticable with the stainless steels, since decarb often nullifies any rust resistance. That's exactly what you're seeing here, INFI is by its nature very stain resistant, in some cases exceeding ats34 and similar high carbon stainless steels. The decarb layer (rarely removed on combat grade knives, never on comp finish blades) is more susceptible to rust and will take bluing far easier than the infi a few microns below it will.
Click to expand...


Many thanks Yoda :thumbup:
 
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