mirror polishing 440-C

bladegrinder

bladegrinder

Well-Known Member
My main steel of choice has been 440-C for a long time, always from the same supplier. lately though they said they can't get the size I want. I have always got excellent mirror finishes on this steel but the other supplier I got some from you could see imperfections at 400 grit, mirror, forget it. so I tried another supplier and had the same results but not as bad, just not exceptable for a mirror finish. so now I"m about to change steels, possibly 154cm. so...there lies my problem, can anyone here recommend a supplier that can guarantee a good mirror finish on there 440-C before I just change steels ? THANKS.........
 
Well, isn't that a huge pain !!! I've used some 154CM and found it works out well. On suggestion from some , I'm now tring some CPM154 with I'm told works a bit better. Frank
 
440C is a nice steel, but you are right that it shouldn't have internal flaws. I guess that can happen with any steel, but it should be a rarity - and I would suggest the steel should be replaced by the supplier. Both Frank's suggestions are great. All things equal, 154CM will outperform 440C in both corrosion resistance and edge retention. Mirror finish is my personal demon, but I'm told the two are similar for finishing. CPM154 is icing on the cake. because of the CPM process, it is twice as tough for the same hardness, which also means you can go thinner behind your primary edge than you normally would. I'm told CPM154 is at least a contender for the best mirror finish of all blade steels.

Rob!
 
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440c is good steel. Maybe the most popular knife steel ever. It is not known for flawless cosmetics. If it has inclusions, that is a problem and should be warrantied. 440c may exhibit a bit of occasional cloudiness or or alloy "blotchiness" and this usually only shows up when it is mirror polished. This is one reason 440c is so economical.
Cpm154 or Elmax has never been reported (since the original first batch of cpm154) to have that issue.
 
BossDog said:
440c is good steel. Maybe the most popular knife steel ever. It is not known for flawless cosmetics. If it has inclusions, that is a problem and should be warrantied. 440c may exhibit a bit of occasional cloudiness or or alloy "blotchiness" and this usually only shows up when it is mirror polished. This is one reason 440c is so economical.
Cpm154 or Elmax has never been reported (since the original first batch of cpm154) to have that issue.
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I concur with bossdog that this should be warrantied, 440C is a fine clean steel and you shouldn't have any visable inclusions?

Are you sure that all rolling/Mill marks & scale have been ground off before you HT and start your Mirror/Satin finish?

Laurence

www.rhinoknives.com
 
Thanks to all that answered my question. I have had inclusions before like dirt or sand that leaves a small pit in the steel and can be removed by grinding or sanding it out, but these two latest examples of worked with had "blotchiness" like big dog said. I'm going to go ahead and try some CPM154. does anyone have a recipe they use for heat treat ? THANKS, STEVE.
 
bladegrinder said:
Thanks to all that answered my question. I have had inclusions before like dirt or sand that leaves a small pit in the steel and can be removed by grinding or sanding it out, but these two latest examples of worked with had "blotchiness" like big dog said. I'm going to go ahead and try some CPM154. does anyone have a recipe they use for heat treat ? THANKS, STEVE.
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Heat Treat the same as ats34. It is nearly the same steel.
 
For CPM154 - foil wrap - 1950F - 45 min soak at temp - plate quench - cryo if available at least 2 hours - temper twice 2 hrs each -- 500F if you did cryo for RHC 60.5 or so -- 400F if no cryo for about RHC 59.
 
you can get cpm 154 from pretty much most the steel sellers at this site. I dont use much of any other steel for serious knives.
 
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