Testing some rebar: can it be forged, hardened or forge welded?

[TechnicusJoe]

 

[ThomasPowers]

Rebar comes in many grades; the larger stuff is generally better quality here in the USA as it gets used for things like Bridges, Skyscrapers, major structures.  Some of the smaller stuff can be very low grade indeed!  Hence the infamous 1983 incident with the radioactive rebar here in the USA and Mexico.

[HojPoj]

My impression from the video is that he acknowledges that not all rebar is the same.

While he mentioned it, probably could have further emphasized that the only way to answer "Is rebar good for ____?" is to *test* whatever bars are at-hand.

[ThomasPowers]

Oh yes he VERY PROPERLY mentioned that his results were for that particular piece of rebar; well done indeed!   I was just mentioning it here for folks not aware of some of the possible issues.  Think of as a gloss for his manuscript.  Of course there are some folks that no matter how much you mention that your results are for a specific item; will go and use something completely different and then complain that they didn't have the same result.

[Hans Richter]

Thomas, is right there are many different types of rebar. Starting from the simple small diameter that are made of low quality (tensile strength, and yield strength = 300MPa) which are cold-set by rolling and have a pressure-stronger metal-grating structure (action = reaction). Then there is the material processed by Joey (started from a diameter of 1/2 in) that is made through the tempcore process, which by definition have a much different chemical composition and a much higher yield strength and tensile strength (500 MPa YS). Orginal is made of reinforcing steel with a hard surface (adherence concrete) and a Martensite 'skin' that extends inwardly from cementite over austenite to ferrit in the core (hence Tempcore), this is achieved by quick quenching the surface and lengthening normalizing the rod with the residual heat in the core. The aim of this treatment is a gradual transition from heart to soft (ductile), since the reinforcing steel must be hard on the outside but also elastic on the inside. However, the moment the rod is heated to above 723 ° C, this structure is lifted from hard to soft, you get an ordinary mild steel with a high concentration of manganese. Probably the reason for the permanent flexibility of the steel and dents in Joey's hammer. And no, I'm not going to start with aluminum micro-alloy rebar and avoidance of free nitrogen for rebar in buildings in earthquake-affected regions .

[Frosty]

1 hour ago, ThomasPowers said:

no matter how much you mention that your results are for a specific item; will go and use something completely different and then complain that they didn't have the same result.

Or worse, call you a liar.

 Frosty The Lucky.

[JHCC]

That's some interesting info, Hans; thanks.

[TechnicusJoe]

On 5/28/2020 at 11:54 AM, Hans Richter said:

Thomas, is right there are many different types of rebar. 

Thanks, Hans! 

I did get a comment on my video from someone who provides no evidence nor anything else to support his claim. 
I don't believe any random internet person's (rediculous) claims, unless I have good reason to believe asserted claims - for example irrefutable evidence.
He said he worked in a steel mill where rebar was produced. 
This person claims lead is used in this process and that the rebar contains lead as well. 
Therefore when I forge the rebar I also expose myself to toxic lead fumes. 

Though to my recollection, leaded alloys (automatenstaal?) crumble when forged. Not well suited for forging. 
Please correct me, if I am wrong. 

I don't smell any fumes coming off of the rebar. I must admit, not-smelling anything does not at all mean there are no fumes!
Therefore it could be, actually. 

And then. I don't see any blue flames/flashes from lead burning. I don't see a white residue (lead oxide or something similar) from on the rebar or anything alike near it. 

I also don't know why they would bother to work with lead in rebar. That doesn't mean it could actually have a use.  I just don't know. 


I would very happily revise my vision, if anyone could confirm lead is used in rebar - if only in a particular case. 
Or provide evidence where and when lead is used in rebar and what functions it has. 

Until then the claim goes on the junk pile of similar claims. For example: Mild steel cannot be forge welded. 
A claim I have debunked countless times - every time I do a forge weld with mild steel, it's busted. 

[ThomasPowers]

Lead would be a bad thing in rebar!  It's added to improve machinability of certain alloys; but would definitely negatively impact weld strength and a lot of rebar is welded.

Of course it's probably a tramp element and present in such low amounts as to not cause issues in good quality rebar; just like phosphorus and sulfur.

[Hans Richter]

Hi Joey, I have to agree with Mr. Powers again (should not become a habit) an average 3.1 certificate issued by an independent testing laboratory on a hot-rolled and Tempcore-treated badge as shown in the chemical composition, Pb (lead) is not even stated because there are no significant quantities / percentages are present. However, you will find the TP values mentioned and hopefully low values of the culprits in reinforcing steel such as phosphor, sulfur and nitrogen because these make the steel less weldable causing cracks (P + S + Cu) or aging (N) in the intercristal sceleton, and of course a lot of manganese as already mentioned. So the lead storry is a fairy tale. I was 6 years manager in a metalware factory (Utrecht) that produced millions of drop forged rebar couplers for the building/construction industry and did 3 years of technical checks on reinforcing steel under the quality mark that was imported in the Netherlands, Germany and Belgium. No worry at all!!!

certifcaat_met_uitleg_(002).pdf

[ThomasPowers]

Hans; feel free to take time off and agree with Frosty every now and then, (he often agrees with me...)  I'm sitting here in my office at work with the door locked, my beard braided and tiny anvils hanging from the braids trying to be agreeable and not let my dwarfish tendencies get out of control...Baruk Khazâd! Khazâd ai-mênu!,...sorry.

(Isolation has meant I get to grow my beard long enough to braid---just in time for summer!  With luck I can keep growing it out and do a really good impression of Santa Claus' evil twin Skippy next December.)

[Frosty]

Sometimes you're right Thomas. 

I shaved for the first time since just after Deb and I got married, she prefers the beard. Did a face time appointment with my General and she told me I wasn't looking well, pretty bad in fact. I told her I didn't need independent confirmation I looked better with my face covered by a beard. She actually blushed. 

Worse, I discovered I have jowls and a dewlap.  I hope I can start going out without a mask so I can let my beard grow.  The sooner the better!

 Frosty The Lucky.

[ThomasPowers]

My wife also prefers my face semi hidden and as she cuts my hair; it often ends up longer than I would have worn it for work reasons.  Of course a smith I know used to accidentally trim his queue when it would flip onto the anvil while he was working hot steel on it.

My first big job I shaved for my interview.  15 years later for my second big job I shaved the beard and kept the mustache for the interview. 10 years later I merely trimmed my facial hair for the 3rd big job interview.  6 years later they got me as I am for my job interview. (Actually I have been told that in IT work; looking like you are marching to a different drummer can impress people with your competence...)

[BillyBones]

I am jealous of you guys who can grow beards. I want one of those long hillbilly beards and have tried many ties to grow one. The itching is so bad after about 3 weeks i have to shave it off. 

[Chris C]

I was at the scrap yard yesterday and saw a piece of rebar that was about 2 1/2" in diameter and 3 foot long.  was tempted to buy it just out of curiosity.  I wonder what it might be good for? (in relationship to the blacksmith's world)

[JHCC]

I have long maintained that the only legitimate use for rebar in blacksmithing is for applications where either (A) you want the texture for aesthetic purposes or (B) the texture doesn't matter. As an example of the first, I like to make rebar bottle openers to give to contractors and demolition folks who let me scavenge structural steel; of the second, my hammer stand is welded up from a bunch of different scrap that was at hand, including both rebar and mechanically twisted 1/2" square from a salvaged balustrade.

For anything else, the variability in carbon content and the added work of removing the texture (by hammering or grinding) makes rebar more trouble than it's worth, in my opinion, especially if you have easy access to stock that is more appropriate to the job at hand.

[Chris C]

I just thought "maybe", since it was so large, it was meant to do something "serious" and might be a bit better than your typical DIY store 1/2" rebar.

[Hans Richter]

Thomas, I often agree with Frosty and share his opinion. You both certainly have several decades more experience of life years and events that you have experienced unlike me and some others.
As for the beard, my profile photo is no longer correct, because of the frequent wearing of a mask, I shaved off my beard. The ladies at home are happy, but can no longer piggyback on the Hipster / artist / blacksmith golf with my baby face. Chris is right, the worst time during a beard's growth period is when the beard hairs start to curl and stick into your skin. That itching terrible.
As for rebar, I regularly use it for my sculptures, I often weld and forge them and the ribbed surface is often part of the artistic appearance. I will not want to miss reinforcing steel for simple and quick to make simple tools and accessories. Below is a photo of a set of quick-made tongs to take my filigree Raku Ceramics out of the glowing kiln for reduction in the wood chip barrels. Even the structure of the kiln is reinforced with rebar rings and parts of the gallows and burner attachment consist of the same material.

[ThomasPowers]

No  the worst time for a beard is when it gets long enough to get caught in machinery!

I've forge trimmed mine a few times but never kissed a lathe or drillpress.

[Frosty]

Long hair, loose clothing dangly jewelry and rotating machinery are NOT YOUR FRIENDS!

 Frosty The Lucky.

[Chris C]

When my family owned the business that included a machine shop, all the men in the office wore clip-on ties.  Nothing more pitiful looking than a guy with his tie wrapped around a chunk of steel on the lathe pulling him in to his death by his tie.  If it rotates, it can kill you quickly.

[Frosty]

There are or were lots of "FatalGrams" about getting caught in rotating machinery. The state shops used to get new posters monthly. The heavy duty shop had one hung for years of a guy working under a truck who's clothes got tangled in the driveshaft. He was wrapped around the transmission's tail shaft two or more times. There is about a hand's width clearance say 5" maybe.

Another was sent to our shop showing a guy who'd gotten caught by drill auger and wound up in the works. The clearance was irrelevant, the auger just mulched him before the helper or geologist got to the kill switch. 

Guys wound up in winch drums were 2-3 times yearly posters.

I can't say how thankful I am I never witnessed one of these.

 Frosty The Lucky.

[JW513]

On 6/1/2020 at 5:01 PM, Frosty said:

Long hair, loose clothing dangly jewelry and rotating machinery are NOT YOUR FRIENDS!

So true,  first thing i do when i get a work sweatshirt is rip that string out for the hood... That would get caught in a skillsaw or grinder or table saw pretty easily.. I shave every day, both head and face so hair isn't a problem... But I hate seeing people not that safety serious on job sites.

Now for on topic, another great video... I have access to all the rebar I want, but i've only used it once forging. 

[ThomasPowers]

I was on oil drilling rigs when they were still "throwing the chain" to tighten a pipe joint.  I got to see one where the chain broke.  Due to extreme luck it was the dead of winter and the hands were wearing a ton of layers of stoutly made canvas and quilting. It didn't cut him in half, just some broken ribs...

[Chris C]

Accidents happen in a split second.  They are more often over before you even know they happened.  I know, I've had my share.  I only have three fingers on my left hand.  Anyone with a strong stomach can request PM'd pictures.