I've made a huge mistake - help IDing steels pre-HT

neetones

neetones

Joined
Apr 30, 2001
Messages
701
Hi friends,

I've been a BF member for a decade or so and used to be very active as a trader/seller/lurker. I took a big break and now am getting back into things as a maker.

I ground out 15 blades on my new KMG but because it was my first batch I was too stupid to actively keep track of what steel I was working with.

So now I have some blades that are 52100 and some that are CPM 154. The problem is that some of them got mixed up and I don't know which is which. I am about to send them to Peter's for heat treat but I need to be sure which ones I'm packaging where.

Any foolproof methods to do so? I tried seeing which would show surface rust first and it seems to help differentiate but I need to be sure.

Any ideas?

Thanks, and I hope to be able to give back soon as I get more steel ground.

Nitin
 
I am thinking that the rust test might be the best way to go. CPM 154 is a stainless and should not produce as much oxidation as 52100. You might try putting a 400 grit finish on them and place the knives in humid place and observe the rate of oxidation. Then separate the two batches and label the two and send out for HT.
 
Try some cold blue ( Touch up Gun Blueing) I do not believe CPM 154 will take blueing or will do so lightly. The 52100 should take it and darken nicely.
 
sceva said:
Try some cold blue ( Touch up Gun Blueing) I do not believe CPM 154 will take blueing or will do so lightly. The 52100 should take it and darken nicely.
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+1, this will tell you the difference immediately
 
The cold blue test will work but if you don't have any around a quick spark test grinding a known piece of the cpm will tell you fast. compared to the sparks of 52100.
 
These all seem like brilliant ideas. I tried the vinegar etch and it worked like a charm...the differences were obvious almost immediately.

Thank you for the help. Off to heat treat! I'll share pics as I work on them when they return.

Nitin
 
zaph1 said:
I would have used the spark test, now that I understand it. Carbon steel will spark much more vigorously than stainless.
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Does that test remove much steel? I'd hate to mess with a (mostly) finished knife, but I don't understand the spark test all that well.

Also, why is that better than a patina or cold blue test?
 
If you have known samples to compare to, just a touch, like 0.1 - 0.5 seconds should do it...
 
If you have a micrometer you can measure the thickness. If the steels came out of the same bar stock you will be able to identify them. For example I have some 52100 from Aldo as well as some cpm-154. They both were ordered at .113-.100 thickness. The 52100 s consistently .105 and the 154-cm is actually consistently .096. Hard to notice by eye but the mic can tell you the difference of the steels.
 
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