Rare 440C steel defect?

Wallace Mutt

Wallace Mutt

Joined
Jan 24, 2016
Messages
503
I don't know what defective steel looks like but I heard there was a time of production that it has happened. Does the pitting here look like a defect or no? I tried to sand it out but the more I sand the more it worsens. Would it be more sought if left alone?
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kinda looks like pitting. strange on 440c but if left outside in elements or used with corrosive material over time. maybe?

is it maybe defective bar stock or plates whichever was used to cut blades from?

whos a metalurgist....tuned in to see feedback.
 
Slightly related. I recall reading that the problem with the NEMO dive knife was that 440C was not resistent to salt water corrosion.
 
This pic is from when I first saw it. I guess sanding it down slightly reduced the pitting but it seems strange that the other side of the blade has pitting almost straight through it.
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It could be pitting or a bad grain or anything like that... I wouldn't have sanded it personally.
 
Wanimator said:
It could be pitting or a bad grain or anything like that... I wouldn't have sanded it personally.
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I only tried sanding it to see if I could smooth out some of the scratches. I used 600-2000 grit wet paper. Camera flash exaggerates the marks.
Do you mind if I ask why you wouldn't have sanded it?
 
This effect is typical for 425m steel. There is a small dot on the blade. You try to grind it out and it becomes bigger and bigger. This propensity for corrosion with shrink holes was the reason for buck to take the 420hc. This steel is a lot more rust proof. I think it is possible buck used a different steel for your knife or it was an accident of the steel supplyer. 440c doesn't show these effects.

Haebbie
 
Haebbie said:
This effect is typical for 425m steel. There is a small dot on the blade. You try to grind it out and it becomes bigger and bigger. This propensity for corrosion with shrink holes was the reason for buck to take the 420hc. This steel is a lot more rust proof. I think it is possible buck used a different steel for your knife or it was an accident of the steel supplyer. 440c doesn't show these effects.

Haebbie
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yes this is typical for 425m but it also happens to 440c which this two liner is
I have several 440c blades that show this
I think it is flaws/impurities in the steal
425m was more resist to salt but it did have a lot of trash in it
that is why buck went to 440hc as I under stood it
 
Isn't there some kinda thing that happens with stainless if it get some carbon steel in it?
I vaguely remember reading that when someone cleaned up a stainless blade with a carbon steel wool, they weren't careful to remove the bits of carbon steel, and when one of them rusted it actually spread to an otherwise stainless blade. Am I just making this up? If not, maybe something like that happened?
 
19-3ben said:
Isn't there some kinda thing that happens with stainless if it get some carbon steel in it?
I vaguely remember reading that when someone cleaned up a stainless blade with a carbon steel wool, they weren't careful to remove the bits of carbon steel, and when one of them rusted it actually spread to an otherwise stainless blade. Am I just making this up? If not, maybe something like that happened?
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stamping stainless with tool steels sometimes leave residue for a lack of a better term and the tool steel rusts...as an example of what your talking about. spyderco had this happen with rustproof...yeah actual rust proof h1 steel with the tooling stamping h1 on the blade and the remants of tool steel rusted while the h1 was fine. rubbed right off.. dont think that has any application in this knifes case though..whther 425 or 440c
 
jbmonkey said:
stamping stainless with tool steels sometimes leave residue for a lack of a better term and the tool steel rusts...as an example of what your talking about. spyderco had this happen with rustproof...yeah actual rust proof h1 steel with the tooling stamping h1 on the blade and the remants of tool steel rusted while the h1 was fine. rubbed right off.. dont think that has any application in this knifes case though..whther 425 or 440c
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Maybe that's what I was thinking of. Thanks for clearing it up for me.
 
Habbie is closest. I have seen this and I think it is from a bad mfg. method/ batch of steel. This steel was not being made by the 'vacuum remelt method' back then. 425M was known to have this in it's steel. Still, this was not the reason Buck went to 420HC. (perhaps a factor)
They went to 420 because the tooling method could produce blades much fast, with less wear. DM
Haebbie said:
This effect is typical for 425m steel. There is a small dot on the blade. You try to grind it out and it becomes bigger and bigger. This propensity for corrosion with shrink holes was the reason for buck to take the 420hc. This steel is a lot more rust proof. I think it is possible buck used a different steel for your knife or it was an accident of the steel supplyer. 440c doesn't show these effects.

Haebbie
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Yes, David, that's correct. It was one not unimportant factor to change, not the reason.

Haebbie
 
The only thing is, that I think this knife dates back to 1967-1970's. Wouldn't 425m been nowhere near Buck's factory at the time?
 
My guess is porosity in the metal too. Segregation of elements, slag or foreign substance. Being on both sides in the same place that whole area is compromised. It wont sand out and if sand blasted it would open up deeper.
So, if a display piece, spa it. Or if you want to use it spa + new blade.
 
Wallace Mutt said:
The only thing is, that I think this knife dates back to 1967-1970's. Wouldn't 425m been nowhere near Buck's factory at the time?
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Wallace, yes. Were not discussing the dates of the steels. The process and steel melting could have been on going at different mills at different times. Just saying these 2 steels showed the same malady. For a point of reference to verify this condition existed. DM
 
Ah, my mistake. Thanks for the info and history lesson guys. Very informative. Just thought I'd ask since I've never seen that before.
 
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