Strange rebar gifted to me by coworker who claims it’s very hard steel

[Skullandbonesforge]

No idea what this stock is I’ve been told it’s a type of rebar tryed to look it up on google got no luck there it’s really shiny despite a bit of surface rust but not shaped like most rebar you see today tell me what you all think and I hope I’m in the right part of the forums thank you also noticed a little tit on the end you’ll see in the picture only time I’ve seen that on steel is when I’m welding Nelson studs down onto deck with 9018 5/32 rod and the studs have a magnesium tip if I’m correct let me know what you all think

 

[JHCC]

Best thing to do if you don't know the alloy is to do a spark test and then cut a bit off the end to test harden.

[Skullandbonesforge]

That’s probably a good idea once I get out of work I’ll give it a shot I’ve just never heard of a good quality piece of rebar ? Maybe it’s just me I’ve heard two different people at work say it was though 

 

[ThomasPowers]

It may surprise you; but the rebar used for things like Nuclear Powerplant Containment structures, Interstate Highway Bridges, Skyscrapers; etc is "good quality rebar"  with good specs and tight controls.  It's not the cheap stuff sold at big box stores though. 

Note that "good quality" does NOT automatically mean "good for blades"; it means it's good for it's intended use!  Aerospace grade 1095 is a *terrible* steel if what you need is 1005.

[JHCC]

Or vice versa.

[arftist]

Larger diameters are less likely to be junk.

[jerry1865]

oddly enough, ive come across some rebar that I was certain to be 4140, I didn't shoot it with the pmi gun simply because I didn't want to take the time to borrow it from work,  but 25 years of turning metal told me it was most likely 4140.

I agree that each piece of rebar needs tested prior to working it, but sometimes you get a good one.

 

[Frazer]

It's very unlikely 4140 was being used for rebar.. I'm not disagreeing that there are different grades, but I don't know what benefit 4140 would have over something less expensive like a medium carbon steel with proper quality controls. 

[Charles R. Stevens]

The stuff at the big box store will surprise you some time, just depends on what junk ended up in the waste stream. The stuff I have been seeing lately air quenches something terribly.  

[Frosty]

13 hours ago, Frazer said:

It's very unlikely 4140 was being used for rebar.. I'm not disagreeing that there are different grades, but I don't know what benefit 4140 would have over something less expensive like a medium carbon steel with proper quality controls. 

While that makes intuitive sense folks manufacturing low rate rebar don't go to that much trouble Frazer, whatever is in the scrap RR gondolas when they load the melter is what's in that batch of rebar. Consider a large manufacturer of 4140 products hauling their scrap once a  month when it hits, say 100 tons. Think the steel mill is going to sort through it or just lift and dump? 

I grew up in Father's metal spinning and machine shop, after a lifetime making a living at it Dad was amazingly good at IDing alloys by how they turned on a lathe. Not always of course but generally very accurate. He'd never guarantee his evaluation though, not even to me.

Frosty The Lucky.

[bluerooster]

I would think that there are some instances where corrosion resistance in re-bar is called for.  Thus requiring a specific alloy containing cr, or some such.

[Steve Sells]

why do you think a little Chrome in an alloy help to prevent corrosion? its Chrome oxides formed by FREE chrome in the matrix that make SS be stainless, The  1% chrome or so in alloys like 5160 and 4140 wont matter