Bearing steel id?

Self Made Knives

Self Made Knives

Well-Known Member
I see a lot of guys using big ball bearings for forging, which I believe they say are 52100. How standard is that, I mean, are pretty much all ball bearings made out of the same steel? My brother gave me these big roller bearings in below in the pics, can I safely assume they are 52100?
bearing steel 1.jpg bearing steel 11.jpg
 
These days you can't ASSUME anything when it comes to what type of steel a given item is made from. Ever since "spec manufacturing" came into the picture it's at best a crap shoot. IF the bearings happen to be marked with the name "Timken" the possibility is good that it's 52100, but if there are no markings, or the name is something else, it's just guessing.
 
Ed, "IF" the bearings are a known 30 yr old bearing could you then "assume" they are 52100??
 
I'd say you have a "decent" chance of that being 52100, or something very similar. At the very least, it'll likely harden into a good knife blade. The forces and application that bearings of that size will typically see aren't going to react well with an inferior or poorly hardened/un-hardenable steel.

I'd say flatten it out, cut a coupon off, and HT like 52100. Then snap it off in a vise and check out the grain.
 
Ed, "IF" the bearings are a known 30 yr old bearing could you then "assume" they are 52100??
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Ken.... the chances are a bit better that the bearings are 52100....the older they are. For many decades 52100 was about the only material bearings were made from (that was back in the day when "quality" was the first priority).

Ed, will you quit raining on my parade!
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:) Just trying to save you some heartache. I suppose I could be a real wiener and say "Sure! those are certainly 52100! But if you don't forge them down right away, or all at once (by hand), they will go "bad"! :)

Seriously.... I'm always suspicious of roller bearings....mainly because the larger roller bearings were the first type of bearings that were not being made of 52100. Hopefully those are 52100.....but as with all recycled stuff, it's a best guess scenario.....all you can do is forge one down, quench test it, and see.
 
Ed, thank you for confirming my understanding of bearing steel..... You Da Man!!!

Ken H>
 
Thanks Ed, I just wish there was some easy magical way to identify steels. I just read a few of those "white papers" from various sources and as Scott said, 440 seems to be a common replacement for 52100. I found a couple charts that list about a dozen or so bearing steels chemical properties. I'd say at least half of them are nearly identical to 52100, but there are few that have way less carbon too. I guess what I find frustrating is how many people are selling ball bearings online as 52100 and how the tv show (which I love by the way) is always forging these big ball bearings into blades. How many of those are mystery steel? I'll bet a bunch of them.
 
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